how many rows and periods are in the periodic table
Period 3 element


A period 3 element is one of the chemical elements in the third row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when the periodic table skips a row and a chemical behaviour begins to repeat, meaning that elements with similar behavior fall into the same vertical columns. The third period contains eight elements: sodium, magnesium, aluminium
19045106
Period 1 element


A period 1 element is one of the chemical elements in the first row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate periodic (recurring) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The first period contains fewer elements than any other row in the table, with only two: hydrogen and
20296874
Period 6 element


A period 6 element is one of the chemical elements in the sixth row (or "period") of the periodic table of the elements, including the lanthanides. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The sixth period contains 32 elements, tied for the most with period 7,
13470047
Period 7 element


A period 7 element is one of the chemical elements in the seventh row (or "period") of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The seventh period contains 32 elements, tied for the most with period 6, beginning with francium
20296885
Period 4 element


A period 4 element is one of the chemical elements in the fourth row (or "period") of the periodic table of the elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The fourth period contains 18 elements, beginning with potassium and ending with krypton. As a rule,
13470027
Period 5 element


A period 5 element is one of the chemical elements in the fifth row (or "period") of the periodic table of the elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The fifth period contains 18 elements, beginning with rubidium and ending with xenon. As a rule,
1859355
Period 2 element


A period 2 element is one of the chemical elements in the second row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases; a new row is started when chemical behavior begins to repeat, creating columns of elements with similar properties. The second period contains the elements lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, and neon. This situation
20296838
The Disappearing Spoon


Genealogy of elements" The author examines and his history. Bunsen had passion for arsenic but an explosion left him half-blind for the rest of his life and because of this he created the Bunsen burner. He discusses many people who contributed to the periodic table, including , the man accredited for creating the first periodic table. Mendeleev predicted other elements that were yet discovered. He put the 62 known elements into columns and rows but he wasn't the only scientist to attempt this. also worked on his own periodic table
21893876
Extended periodic table


An extended periodic table theorizes about chemical elements beyond those currently known in the periodic table and proven up through oganesson, which completes the seventh period (row) in the periodic table at atomic number ("Z") 118. If further elements with higher atomic numbers than this are discovered, they will be placed in additional periods, laid out (as with the existing periods) to illustrate periodically recurring trends in the properties of the elements concerned. Any additional periods are expected to contain a larger number of elements than the
19154566
Log trigger


it stores how the data were in the period of time between the codice_5 (included) and codice_6 (not included). For each entity (distinct primary key) on the original table, the following structure is created in the history table. Data is shown as example. Notice that if they are shown chronologically the codice_6 column of any row is exactly the codice_5 of its successor (if any). It does not mean that both rows are common to that point in time, since -by definition- the value of codice_6
2170043
Period (periodic table)


A period in the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, groups of elements in the same column have similar chemical and physical properties, reflecting the periodic law. For example, the alkali metals lie in the first column (group 1) and share similar properties, such as high reactivity and the tendency to lose one electron to arrive
5268634
Periodic table


The periodic table, also known as the periodic table of elements, is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties. The structure of the table shows "periodic trends". The seven rows of the table, called periods, generally have metals on the left and non-metals on the right. The columns, called groups, contain elements with similar chemical behaviours. Six groups have accepted names as well as assigned numbers: for example, group
3472826
Periodic trends


Periodic trends are specific patterns in the properties of chemical elements that are revealed in the periodic table of elements. Major periodic trends include electronegativity, ionization energy, electron affinity, atomic radii, ionic radius, metallic character, and chemical reactivity. Periodic trends arise from the changes in the atomic structure of the chemical elements within their respective periods (horizontal rows) and groups in the periodic table. These laws enable the chemical elements to be organized in the periodic table based on their atomic structures and properties. Due to the periodic
9088947
Periodic table


development of modern quantum mechanical theories of electron configurations within atoms, it became apparent that each period (row) in the table corresponded to the filling of a quantum shell of electrons. Larger atoms have more electron sub-shells, so later tables have required progressively longer periods. In 1945, Glenn Seaborg, an American scientist, made the suggestion that the actinide elements, like the lanthanides, were filling an f sub-level. Before this time the actinides were thought to be forming a fourth d-block row.
3472879
Alternative periodic tables


an alternative positioning of hydrogen, helium and the lanthanides was published by EG Marks and JA Marks in 2010. From Mendeleev's original periodic table, elements have been basically arranged by valence (groups in columns) and the repetition therein (periods in rows). Over the years and with discoveries in atomic structure, this schema has been adjusted and expanded, but not changed as a principle. The oldest periodic table is the short form table (columns I–VIII) by Dmitri Mendeleev, which shows secondary chemical kinships.
13927869
Block (periodic table)


pairs of electrons; hence, the block includes ten columns in the periodic table. The f-block is in the center-left of a 32-column periodic table but is footnoted in 18-column tables. These elements are not generally considered part of any group. They are often called inner transition metals because they provide a transition between the s-block and d-block in the 6th and 7th row (period), in the same way that the d-block transition metals provide a transitional bridge between the s-block
2070048
Periodic table


number of an element is the same as the number of protons in its nucleus, the modern periodic table arranges the elements according to their atomic number, and relative to their atomic mass, the way Mendeleev did. The periodic table is used to predict the properties of new synthetic elements before they are produced and studied. In 1871, Mendeleev published his periodic table in a new form, with groups of similar elements arranged in columns rather than in rows, and those columns numbered I to VIII corresponding with the element's oxidation
3472876
Atomic radius


as spheres. This is only a crude approximation, but it can provide quantitative explanations and predictions for many phenomena, such as the density of liquids and solids, the diffusion of fluids through molecular sieves, the arrangement of atoms and ions in crystals, and the size and shape of molecules. Atomic radii vary in a predictable and explicable manner across the periodic table. For instance, the radii generally decrease along each period (row) of the table, from the alkali metals to the noble gases; and increase down each
4346515
History of the periodic table


The periodic table is an arrangement of the chemical elements, which are organized on the basis of their atomic numbers, electron configurations and recurring chemical properties. Elements are presented in order of increasing atomic number. The standard form of the table consists of a grid with rows called periods and columns called groups. The history of the periodic table reflects over two centuries of growth in the understanding of chemical properties, with major contributions made by Antoine-Laurent de Lavoisier, Johann Wolfgang Döbereiner, John Newlands, Julius Lothar Meyer, Dmitri
22081039
Henry D. Hubbard


Henry D. Hubbard (1870-1943) was a member of the U.S. Bureau of Standards in the 1920s. He modernized Mendeleev's periodic table and in 1924 he produced a Periodic Table of Elements (called the Periodic Chart of the Atoms) which was distributed to schools and universities. This version of the periodic table placed the main groups in columns with some later groups taking up two rows per period and the Group VIIIB transition metals displayed out to the right of the noble gases. The noble gases themselves were shown first in
4813708
Period (periodic table)


at a noble-gas electronic configuration. As of 2016, a total of 118 elements have been discovered and confirmed. Modern quantum mechanics explains these periodic trends in properties in terms of electron shells. As atomic number increases, shells fill with electrons in approximately the order shown at right. The filling of each shell corresponds to a row in the table. In the s-block and p-block of the periodic table, elements within the same period generally do not exhibit trends and similarities in properties (vertical trends down
5268635
Kayles


find the value of formula_2 on the table, write formula_1 as formula_9, and look at row a, column b: At this point, the nim-value sequence becomes periodic with period 12, so all further rows of the table are identical to the last row. Because certain positions in Dots and Boxes reduce to Kayles positions, it is helpful to understand Kayles in order to analyze a generic Dots and Boxes position. Under normal play, Kayles can be solved in polynomial time using the Sprague-Grundy theory. "
19950564
Period 3 element


, silicon, phosphorus, sulfur, chlorine, and argon. The first two, sodium and magnesium, are members of the s-block of the periodic table, while the others are members of the p-block. Note that there is a 3d subshell, but it is not filled until period 4, such giving the period table its characteristic shape of "two rows at a time". All of the period 3 elements occur in nature and have at least one stable isotope. "Sodium" (symbol Na
19045107
Thorium


sixth row was considered to be a one-off fluke. In 1892, British chemist Henry Bassett postulated a second extra-long periodic table row to accommodate known and undiscovered elements, considering thorium and uranium to be analogous to the lanthanides. In 1913, Danish physicist Niels Bohr published a theoretical model of the atom and its electron orbitals, which soon gathered wide acceptance. The model indicated that the seventh row of the periodic table should also have f-shells filling before the d-shells that were filled in the transition
10740865
Iron group


chromium and manganese — five elements that are exceptionally abundant, both on Earth and elsewhere in the universe, compared to their neighbors in the periodic table. In chemistry, "iron group" used to refer to iron and the next two elements in the periodic table namely cobalt and nickel, also called the "iron triad". Those are the top elements of groups 8, 9, and 10 of the periodic table; or the top row of "group VIII" in the old (pre-1990) IUPAC system, or
13074439
Periodic table


an increasing distance between valence electrons and the nucleus. There are exceptions to these trends: for example, in group 11, electronegativity increases farther down the group. A "period" is a horizontal row in the periodic table. Although groups generally have more significant periodic trends, there are regions where horizontal trends are more significant than vertical group trends, such as the f-block, where the lanthanides and actinides form two substantial horizontal series of elements. Elements in the same period show trends in atomic radius, ionization energy
3472840
Period 7 element


respectively) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table (32 columns) shows the lanthanide and actinide series in their proper columns, as parts of the table's sixth and seventh rows (periods). "Transactinide elements" (also, transactinides, or super-heavy elements) are the chemical elements with atomic numbers greater than those of the
20296896
Atomic orbital


this condition is unstable. The electron will eventually lose energy (by releasing a photon) and drop into the lower orbital. Thus, electrons fill orbitals in the order specified by the energy sequence given above. This behavior is responsible for the structure of the periodic table. The table may be divided into several rows (called 'periods'), numbered starting with 1 at the top. The presently known elements occupy seven periods. If a certain period has number "i", it consists of elements whose outermost electrons
861606
Legendre symbol


| "p") or ("a"/"p"). The sequence ("a" | "p") for "a" equal to 0, 1, 2... is periodic with period "p" and is sometimes called the Legendre sequence, with {0,1,−1} values occasionally replaced by {1,0,1} or {0,1,0}. Each row in the following table can be seen to exhibit periodicity, just as described. The following is a table of values of Legendre symbol formula_10 with "p" ≤ 127
18792827
Atomic radii of the elements (data page)


, the value of the radius may depend on the atom's state and context. Atomic radii vary in a predictable and explicable manner across the periodic table. For instance, the radii generally decrease rightward along each period (row) of the table, from the alkali metals to the noble gases; and increase down each group (column). The radius increases sharply between the noble gas at the end of each period and the alkali metal at the beginning of the next period. These trends of the atomic radii (and
20409724
Chemistry


periodic table is arranged in groups, or columns, and periods, or rows. The periodic table is useful in identifying periodic trends. A "compound" is a pure chemical substance composed of more than one element. The properties of a compound bear little similarity to those of its elements. The standard nomenclature of compounds is set by the International Union of Pure and Applied Chemistry (IUPAC). Organic compounds are named according to the organic nomenclature system. The names for inorganic compounds are created according to the inorganic nomenclature system
4896859
Fist of Zen


consists of nine "Zen rituals", each of which presents the victim with some form of pain or discomfort, and must be completed in silence, and sometimes in a given period of time. Each ritual is first presented by its name, which more or less describes the task to be performed, and how many times and/or in what period of time. The participants then appear seated at a table. They must then get their hand in a cardboard box put in the middle of the table, and get a ball
21648766
Extended periodic table (detailed cells)


, they will be placed in additional periods, laid out (as with the existing periods) to illustrate periodically recurring trends in the properties of the elements concerned. Any additional periods are expected to contain a larger number of elements than the seventh period, as they are calculated to have an additional so-called g-block, containing 18 elements with partially filled "g-orbitals" in each period. An eight-period table containing this block was suggested by Glenn T. Seaborg in 1969. It is not known how
17622221
Period 6 element


is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods). Lanthanum is a chemical element with the symbol La and atomic number 57. It is the first element in the lanthanide series. It is a soft, ductile, silvery-white metal that tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. It is the eponym
13470059
Periodic table


single element. Elements with no stable isotopes have the atomic masses of their most stable isotopes, where such masses are shown, listed in parentheses. In the standard periodic table, the elements are listed in order of increasing atomic number "Z" (the number of protons in the nucleus of an atom). A new row ("period") is started when a new electron shell has its first electron. Columns ("groups") are determined by the electron configuration of the atom; elements with the same
3472831
The Disappearing Spoon


elements": Sam Kean begins this book by explaining the basics of the periodic table and how it works. He explains the set-up of the table and why it is modified the way it is. He emphasizes the importance of its organization and the reasons as to why it must be this way. He discusses how the periodic table would not function if it were not for the layout. He states that an elements position describes its function and strength. He describes the table of elements as a castle and the elements
21893871
Atomic orbital


order of filling is given in matrix form, with increasing principal quantum numbers starting the new rows ("periods") in the matrix. Then, each subshell (composed of the first two quantum numbers) is repeated as many times as required for each pair of electrons it may contain. The result is a compressed periodic table, with each entry representing two successive elements: Although this is the general order of orbital filling according to the Madelung rule, there are exceptions, and the actual electronic energies of each element are
861609
Tennessine


the near future (2017–2018) to investigate the properties of nuclear reactions with a titanium-50 beam, which becomes necessary to synthesize elements beyond oganesson. Tennessine is expected to be a member of group 17 in the periodic table, below the five halogens; fluorine, chlorine, bromine, iodine, and astatine, each of which has seven valence electrons with a configuration of . For tennessine, being in the seventh period (row) of the periodic table, continuing the trend would predict a valence electron configuration of , and it would
18786177
Chemical element


, and thus are not known to occur in nature at all. The properties of the chemical elements are often summarized using the periodic table, which powerfully and elegantly organizes the elements by increasing atomic number into rows ("periods") in which the columns ("groups") share recurring ("periodic") physical and chemical properties. The current standard table contains 118 confirmed elements as of 2019. Although earlier precursors to this presentation exist, its invention is generally credited to the Russian chemist Dmitri Mendeleev in 1869,
5775742
Periodic table


an expanded version of his (Meyer's) table of 1864. They both constructed their tables by listing the elements in rows or columns in order of atomic weight and starting a new row or column when the characteristics of the elements began to repeat. The recognition and acceptance afforded to Mendeleev's table came from two decisions he made. The first was to leave gaps in the table when it seemed that the corresponding element had not yet been discovered. Mendeleev was not the first chemist to do so, but he was the
3472872
Periodic table


rows of the periodic table. The first 94 elements all occur naturally, though some are found only in trace amounts and a few were discovered in nature only after having first been synthesized. Elements 95 to 118 have only been synthesized in laboratories or nuclear reactors. The synthesis of elements having higher atomic numbers is currently being pursued: these elements would begin an eighth row, and theoretical work has been done to suggest possible candidates for this extension. Numerous synthetic radionuclides of naturally occurring elements have also been produced in laboratories. Each
3472829
Chemical element


history of the discovery and use of the elements began with primitive human societies that found native elements like carbon, sulfur, copper and gold. Later civilizations extracted elemental copper, tin, lead and iron from their ores by smelting, using charcoal. Alchemists and chemists subsequently identified many more; all of the naturally occurring elements were known by 1950. The properties of the chemical elements are summarized in the periodic table, which organizes the elements by increasing atomic number into rows ("periods") in which the columns ("
5775708
Lanthanide


a selected single element of each series (either lanthanum and actinium, or lutetium and lawrencium) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods). The 1985 International Union of Pure and Applied Chemistry “Red Book” (p.
18665636
Actinide


actinium or lawrencium, respectively) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods). Like the lanthanides, the actinides form a family of elements with similar properties. Within the actinides, there are two overlapping groups: transuranium elements
2025453
Period 6 element


in the d shell. However, both elements are often included in any general discussion of the chemistry of the lanthanide elements. In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table, with placeholders or else a selected single element of each series (either lanthanum or lutetium, and either actinium or lawrencium, respectively) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention
13470058
The Disappearing Spoon


as bricks to build this castle. He then discusses how the periodic table contains, and is organized into, metals, gases, noble gases, halogens, etc. Kean also discusses how how ions work overall. He describes how ions are made when atoms connects with electrons by either giving electrons or taking electrons to another molecule to obtain a net electrical charge. He states the importance the net electrical charge has on the elements and the period table placement. He covers the electron shells and how certain elements hide electrons and do
21893872
Electron affinity


. Although "E" varies greatly across the periodic table, some patterns emerge. Generally, nonmetals have more positive "E" than metals. Atoms whose anions are more stable than neutral atoms have a greater "E". Chlorine most strongly attracts extra electrons; neon most weakly attracts an extra electron. The electron affinities of the noble gases have not been conclusively measured, so they may or may not have slightly negative values. "E" generally increases across a period (row) in the periodic table prior to
19869407
Extended periodic table


. Other islands of stability beyond the known elements may also be possible, including one theorized around element 164, though the extent of stabilizing effects from closed nuclear shells is uncertain. It is not clear how many elements beyond the expected island of stability are physically possible, whether period 8 is complete, or if there is a period 9. The International Union of Pure and Applied Chemistry (IUPAC) defines an element to exist if its lifetime is longer than 10 seconds (0.01 picoseconds, or 10 femtoseconds), which is
19154570
Periodic table


group 3. Such an underlying truth, if it exists, is thought to have not yet been discovered. In its absence, the many different forms of periodic table can be regarded as variations on the theme of chemical periodicity, each of which explores and emphasizes different aspects, properties, perspectives and relationships of and among the elements. In celebration of the periodic table's 150th anniversary, the United Nations declared the year 2019 as the International Year of the Periodic Table, celebrating "one of the most significant achievements in science
3472916
Extended periodic table


Aufbau principle would predict the eighth row to fill orbitals in the order 8s, 5g, 6f, 7d, 8p; but after element 120, the proximity of the electron shells makes placement in a simple table problematic. Although a simple extrapolation of the periodic table, following Seaborg's original concept, would put the elements after 120 as follows: 121-138 form the g-block superactinides; 139-152 form the f-block superactinides, 153-161 would be transition metals; 162-166 post-
19154581
History of the periodic table


these elements belonged to a different series, which would explain why their chemical properties, in particular the instability of higher oxidation states, were different from predictions. In 1945, against the advice of colleagues, he proposed a significant change to Mendeleev's table: the actinide series. Seaborg's actinide concept of heavy element electronic structure, predicting that the actinides form a transition series analogous to the rare earth series of lanthanide elements, is now well accepted and included in the periodic table. The actinide series is the second row of
22081075
Group 8 element


), the noble gases. While groups (columns) of the periodic table are sometimes named after their lighter member (as in "the oxygen group" for group 16), the term iron group does "not" mean "group 8". Most often, it means a set of adjacent elements on period (row) 4 of the table that includes iron, such as chromium, manganese, iron, cobalt, and nickel; or only the last three; or some other set — depending on the context
15956140
Gibbs sampling


matter how long the burn-in period is. This is because in the true distribution, the zero vector occurs half the time, and those occurrences are randomly mixed in with the nonzero vectors. Even a small sample will see both zero and nonzero vectors. But Gibbs sampling will alternate between returning only the zero vector for long periods (about formula_58 in a row), then only nonzero vectors for long periods (about formula_58 in a row). Thus convergence to the true distribution is extremely slow, requiring much more
21194663
Period 7 element


and thorium, and synthetically produced plutonium are the most abundant actinides on Earth. These are used in nuclear reactors and nuclear weapons. Uranium and thorium also have diverse current or historical uses, and americium is used in the ionization chambers of most modern smoke detectors. In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table, with placeholders or else a selected single element of each series (either lanthanum or lutetium, and either actinium or lawrencium,
20296895
SQL problems requiring cursors


represents types of marbles. The four text columns represent four marble characteristics. Each characteristic has two values for a total of 16 types of marbles. The "quantity" column represents how many marbles of that type we have. The task is to create a second table holding one row for each marble of that type. Thus, the target table would have the four text columns, and a total of 40 + 20 + 20 + 10 + ... + 10 + 5 = 270 rows. Source table: Table to generate
10948671
Periodic table


these it is element 172, rather than element 168, that emerges as the next noble gas after oganesson, although these must be regarded as speculative as no complete calculations have been done beyond element 123. The number of possible elements is not known. A very early suggestion made by Elliot Adams in 1911, and based on the arrangement of elements in each horizontal periodic table row, was that elements of atomic weight greater than circa 256 (which would equate to between elements 99 and 100 in modern-day terms) did
3472911
Diagonal relationship


in to horizontal rows and vertical columns makes certain relationships more apparent (periodic law). Moving rightward and descending the periodic table have opposite effects on atomic radii of isolated atoms. Moving rightward across the period decreases the atomic radii of atoms, while moving down the group will increase the atomic radii. Similarly, on moving rightward a period, the elements become progressively more covalent, less basic and more electronegative, whereas on moving down a group the elements become more ionic, more basic and less electronegative. Thus, on both
16991780
B visa


elicits a period of stay (maximum 6 months) recorded by the Customs and Border Protection officer at the port of entry on the individual's form I-94. The validity period determines how long the visa may be used to enter the U.S., while the period of stay determines how long the person may stay in the U.S. after each entry. Validity periods per country are listed in the U.S. Department of State Visa Reciprocity Tables and vary from 1 month for the Democratic Republic of the Congo (with lower issuance fee), 1
6658238
One-to-many (data model)


one-to-many relationship exists when one row in table A may be linked with many rows in table B, but one row in table B is linked to only one row in table A. It is important to note that a one-to-many relationship is not a property of the data, but rather of the relationship itself. A list of authors and their books may happen to describe books with only one author, in which case one row of the books table will refer to only one row of the
9738237
Metaclass (Semantic Web)


to be enumerated over, while preserving the ability to inherit from types. For example, metaclasses could allow a machine reasoner to infer from a human-friendly ontology how many elements are in the periodic table, or, given that number of protons is a property of chemical element and isotopes are a subclass of elements, how many protons exist in the isotope hydrogen-2. Metaclasses are sometime organized by levels, in a similar way to the simple Theory of types where classes that are not metaclasses are assigned the first level, classes
8254562
1992–93 Southampton F.C. season


hosts in a single five-minute period, with a consolation goal scored by Richard Hall later on. During this period, the Hampshire side made it to a peak of ninth in the table. After three losses in a row though, Southampton were again struggling to regain a respectable position in the league table, although did pick up a 1–0 win over Chelsea late in the campaign. The final run of games started with a disappointing 2–5 loss to Sheffield Wednesday, followed by a goalless draw with Everton and frustrating losses against
13952436
Polarizability


with tightly bound electrons. On rows of the periodic table, polarizability therefore decreases from left to right. Polarizability increases down on columns of the periodic table. Likewise, larger molecules are generally more polarizable than smaller ones. Water is a very polar molecule, but alkanes and other hydrophobic molecules are more polarizable. Water with its permanent dipole is less likely to change shape due to an external electric field. Alkanes are the most polarizable molecules. Although alkenes and arenes are expected to have larger polarizability than alkanes because of their higher
3002010
Laver table


satisfies the equations and The latter is sometimes referred to as the "self-distributive law", and sets satisfying only that property are called shelves. The resulting table is then called the "n"-th Laver table; for example, for "n" = 2, we have: There is no known closed-form expression to calculate the entries of a Laver table directly. When looking at the first row of entries in a Laver table, it can be seen that the entries repeat with a certain periodicity "m"
21353638
Table of nuclides (segmented, narrow)


to Periodic table ← Previous | Next →Go to Unitized table (all elements)Go to Periodic table ← Previous | Next →Go to Unitized table (all elements)Go to Periodic table ← Previous | Next →Go to Unitized table (all elements)Go to Periodic table ← Previous | Next →Go to Unitized table (all elements)Go to Periodic table ← Previous | Next →Go to Unitized table (all elements)Go to Periodic table ← Previous | Next →Go to Unitized table (all elements)Go to Periodic table ← Previous | Next →Go to Unitized table (all elements)Go to Periodic
14639947
Block (periodic table)


and p-block in the 4th and 5th rows. The known f-block elements come in two series, the lanthanides of period 6 and the radioactive actinides of period 7. All are metals. Because the f-orbital electrons are less active in determining the chemistry of these elements, their chemical properties are mostly determined by outer s-orbital electrons. Consequently, there is much less chemical variability within the f-block than within the s-, p-, or d-blocks. The f-block elements are
2070049
Periodic table


shielding by d and f electrons. A uniform decrease in electron affinity only applies to group 1 atoms. The lower the values of ionization energy, electronegativity and electron affinity, the more metallic character the element has. Conversely, nonmetallic character increases with higher values of these properties. Given the periodic trends of these three properties, metallic character tends to decrease going across a period (or row) and, with some irregularities (mostly) due to poor screening of the nucleus by d and f electrons, and relativistic effects,
3472860
William Odling


William Odling, FRS (5 September 1829 in Southwark, London – 17 February 1921 in Oxford) was an English chemist who contributed to the development of the periodic table. In the 1860s Odling, like many chemists, was working towards classifying the elements, an effort that would eventually lead to the periodic table of elements. He was intrigued by atomic weights and the periodic occurrence of chemical properties. William Odling and Lothar Meyer drew up tables similar, but with improvements on, Dmitri Mendeleev's original table. Odling drew up
18442222
Johannes Mathesius


ambition of a clerical calling, and he became a theological student at Wittenberg. The recommendations of Justus Jonas and Georg Rörer got him the prized honor of a seat at Luther's table. It is not known exactly how long Mathesius was Luther's guest, but it was probably no longer than the period of May to November 1540 covered by his notes of the "Table Talk". He left Luther's house because he had collected pupils to tutor; at first Luther boarded as many as four of Mathesius's pupils,
5438755
Thomas Rowe Edmonds


theory, Edmonds took up observations of Richard Price, dividing life into three periods (childhood, "manhood" from age 12 to 55, and old age). He quantified mortality by using different geometric progressions in each period. His table became known as "Edmonds's Mean Mortality". He persisted into the 1860s with his piecewise approach, though by then with two periods, rather than the sigmoid curve model of Gompertz. But Edmonds came in for some rough handling for his continuing assertions of the independence of his model
2757722
History of the periodic table


that some discoveries were duplicates or misidentifications. It was also believed that radioactive decay violated one of the central principles of the periodic table, namely that chemical elements could not undergo transmutations and always had unique identities. Frederick Soddy and Kazimierz Fajans found in 1913 that although these substances emitted different radiation, many of these substances were identical in their chemical characteristics, so shared the same place on the periodic table. They became known as isotopes, from the Greek "" ("same place"). Austrian chemist Friedrich Paneth cited
22081066
Stateful firewall


. Sessions that do not match any policy are denied, as packets that do not match an existing table entry. In order to prevent the state table from filling up, sessions will time out if no traffic has passed for a certain period. These stale connections are removed from the state table. Many applications therefore send keepalive messages periodically in order to stop a firewall from dropping the connection during periods of no user-activity, though some firewalls can be instructed to send these messages for applications. Depending on the connection protocol
2216468
Database trigger


table. Row level triggers would execute once for each row that is affected by the UPDATE. It is important to keep in mind if no rows are affected by the UPDATE command, the trigger will not execute any code within the trigger. Statement level triggers will be called once regardless of how many rows are affected by the UPDATE. Here it is important to note that even if the UPDATE command didn't affect any rows, the code within the trigger will still be executed once. Using the BEFORE and AFTER options determine
19841154
Ackermann function


rules in the original definition. For example, one can fully evaluate formula_25 in the following way: To demonstrate how formula_27's computation results in many steps and in a large number: Computing the Ackermann function can be restated in terms of an infinite table. First, place the natural numbers along the top row. To determine a number in the table, take the number immediately to the left. Then use that number to look up the required number in the column given by that number and one row up. If there
2599343
Period 6 element


, also known as the "rare earths". Many lanthanides are known for their magnetic properties, such as neodymium. Many period 6 transition metals are very valuable, such as gold, however many period 6 other metals are incredibly toxic, such as thallium. Period 6 contains the last stable element, lead. All subsequent elements in the periodic table are radioactive. After bismuth, which has a half-life or more than 10 years, polonium, astatine, and radon are some of the shortest-lived and rarest
13470049
Trace table


A trace table is a technique used to test algorithms, in order to make sure that no logical errors occur while the algorithm is being processed. The table usually takes the form of a multi-column, multi-row table; With each column showing a variable, and each row showing each number input into the algorithm and the subsequent values of the variables. Trace tables are typically used in schools and colleges when teaching students how to program. They can be an essential tool in teaching students how a certain algorithm works
9459071
Extended periodic table


seventh period, as they are calculated to have an additional so-called "g-block", containing at least 18 elements with partially filled g-orbitals in each period. An "eight-period table" containing this block was suggested by Glenn T. Seaborg in 1969. The first element of the g-block may have atomic number 121, and thus would have the systematic name unbiunium. Despite many searches, no elements in this region have been synthesized or discovered in nature. According to the orbital approximation in
19154567
Valence electron


can be determined by the periodic table group (vertical column) in which the element is categorized. With the exception of groups 3–12 (the transition metals), the units digit of the group number identifies how many valence electrons are associated with a neutral atom of an element listed under that particular column. The electrons that determine how an atom reacts chemically are those whose average distance from the nucleus is greatest; that is, those with the highest energy. For a main group element, the valence electrons are defined as those
11942307
Periodic table of topological invariants


of a many-band system in formula_46 dimensions can be labeled by the elements of the formula_46-th homotopy group of the symmetric space. These groups are displayed in this table, called the periodic table of topological insulators: There may also exist weak topological invariants (associated to the fact that the suspension of the Brillouin zone is in fact equivalent to a formula_66 sphere wedged with lower-dimensional spheres), which are not included in this table. Furthermore, the table assumes the limit of an infinite number of bands, i.e. involves
14827437
Rutherfordium


Rutherfordium is a synthetic chemical element with the symbol Rf and atomic number 104, named after New Zealand physicist Ernest Rutherford. As a synthetic element, it is not found in nature and can only be created in a laboratory. It is radioactive; the most stable known isotope, Rf, has a half-life of approximately 1.3 hours. In the periodic table of the elements, it is a d-block element and the second of the fourth-row transition elements. It is a member of the 7th period and
6330063
Timeline of conflict in Anglo-Saxon Britain


dates. Constructing a chronology of the early Anglo-Saxon period, and how the Anglo-Saxons took over land in Britain from Romano-Britons (Celtic-speakers, Latin-speakers, or both), is highly complex. The limitations of source material place restrictions on just how accurate any chronology can be. As an example, the following table shows how much variation there is between historians on just one date, the Battle of Badon: Much of the dating of the period comes from Bede (672/673–735),
15960419
Nonmetal


valences other than the lowest for their group (that is, 3, 2, 1, or 0) for example in PCl, SF, IF, and XeF. Period four elements immediately after the first row of the transition metals, such as selenium and bromine, have unusually small atomic radii because the 3d electrons are not effective at shielding the increased nuclear charge, and smaller atomic size correlates with higher electronegativity. Immediately to the left of most nonmetals on the periodic table are "metalloids" such as boron, silicon,
13626084
The Disappearing Spoon


not share and others do share. Kean describes electron behavior as being the guiding point to what forms the period table. Toward the end of this chapter he speaks of Maria Goeppert-Mayer and her contributions to science. "The fathers of the periodic table" In this chapter, the author focuses on the relationships between carbon, silicon, and germanium. He explains how carbon is the backbone of amino acids and the building blocks to everything. He discusses that because of carbon, amino acids all stick together. Then,
21893873
Pivot table


data and highlight the desired information. The usage of a pivot table is extremely broad and depends on the situation. The first question to ask is, "What am I seeking?" In the example here, let us ask, "How many "Units" did we sell in each "Region" for every "Ship Date?"": A pivot table usually consists of "row", "column" and "data" (or "fact") fields. In this case, the column is
19176001
University rowing (UK)


to Boston that year, with Newcastle topping the medal table. The 2014 event was cancelled due to bad weather, It was held in Boston again in 2015, with racing on Saturday only for the "intermediate" and "championship" crews. Newcastle topped the medal table and won the men's Victor Ludorum while Durham, who were second in the medal table, took the women's Victor Ludorum and the overall Victor Ludorum. In 2015, BUCS sought a new host for a three-year period (2016–2018).
4064807
History of the periodic table


fractional distillation to separate air, Ramsay discovered three more noble gases in 1898: neon, krypton, and xenon. Although Mendeleev's table predicted several undiscovered elements, it did not predict the existence of noble gases. Mendeleev added them to the table as Group 0 in 1902, without disturbing the basic concept of the periodic table. In addition to the predictions of scandium, gallium, and germanium that quickly were realized, Mendeleev's 1871 table left many more spaces for undiscovered elements, though he did not provide detailed predictions of
22081058
Betsy Ross (solitaire)


The table below shows how this is arranged: The cards on the second row compose the foundations themselves, while the cards on the row above denote how the cards should be built on the foundations. The foundation placed under the ace starts with the two and it is built in ones. The foundation under the two starts with the four and it is built in twos, and so on. The table below shows how the foundations should be built: What makes this different from Calculation is how the cards in the stock are
13755269
Periodic table


(as shown at various other points in this article), is attributable to Horace Groves Deming. In 1923, Deming, an American chemist, published short (Mendeleev style) and medium (18-column) form periodic tables. Merck and Company prepared a handout form of Deming's 18-column medium table, in 1928, which was widely circulated in American schools. By the 1930s Deming's table was appearing in handbooks and encyclopedias of chemistry. It was also distributed for many years by the Sargent-Welch Scientific Company. With the
3472878
The Disappearing Spoon


The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements, is a 2010 book by science reporter Sam Kean. The book was first published in hardback on July 12, 2010 through Little, Brown and Company and was released in paperback on June 6, 2011 through Little, Brown and Company's imprint Back Bay Books. The book focuses on the history of the periodic table by way of stories showing how each element affected the people who discovered
21893869
The Disappearing Spoon


discussing the measurement of alpha and how it was 1/136 but then it was changed 1/137.0359. Kean discusses these topics to emphasize the measures people would go through to be precise. "Above (and beyond) the periodic table" Last but not least Sam Kean talks about francium, "Magic elements" and the future of the periodic table. The most anyone has every acquired of Francium is ten thousand atoms and it only lasted for twenty minutes. Since Francium is very rare than its even more difficult to find astatine and even
21893906
Periodic table


g-block for the next 18 elements, and 30 additional elements continuing the current f-, d-, and p-blocks, culminating in element 168, the next noble gas. More recently, physicists such as Pekka Pyykkö have theorized that these additional elements do not follow the Madelung rule, which predicts how electron shells are filled and thus affects the appearance of the present periodic table. There are currently several competing theoretical models for the placement of the elements of atomic number less than or equal to 172. In all of
3472910
Iron group


In chemistry and physics, the iron group refers to elements that are in some way related to iron; mostly in period (row) 4 of the periodic table. The term has different meanings in different contexts. In chemistry, the term is largely obsolete, but it often means iron, cobalt, and nickel, also called the iron triad; or, sometimes, other elements that resemble iron in some chemical aspects. In astrophysics and nuclear physics the term is still quite common, and it typically means those three plus
13074438
Spin states (d electrons)


factors that affect the Δ: the period (row in periodic table) of the metal ion, the charge of the metal ion, and the field strength of the complex's ligands as described by the spectrochemical series. In order for low spin splitting to occur, the energy cost of placing an electron into an already singly occupied orbital must be less than the cost of placing the additional electron into an e orbital at an energy cost of Δ. If the energy required to pair two electrons is greater than the energy cost of
6781809
Jim Shooter


Robot Fighter. Shooter brought many of Marvel's creators to Valiant, including Bob Layton and Barry Windsor-Smith, as well as industry veterans such as Don Perlin. Valiant also established "knob row" — taking in raw talent and teaching them how to make comics Valiant-style – and launched many careers, most notably Joe Quesada's. Occasionally over the years, Shooter was required to fill in as penciller on various books he wrote and/or oversaw as editor. During his period as Valiant's publisher, money and talent
335265
Pueblo I Period


and a covering of mud. Later in the period, stone slabs were sometimes used around the dwelling foundation. The pueblos made of several rooms that formed a straight row or in a crescent shape. Sometimes they built the dwellings two rows thick with a combination of living rooms with fire pits and storage rooms. J. Richard Ambler describes how Pueblo I architectural changes reflect societal changes: The change in village layout would seem to reflect a basic change in village social organization from a loosely integrated group of related families to a tightly integrated
18994200
Hydrogen fuel


Hydrogen fuel is a zero-emission fuel when burned with oxygen. It can be used in fuel cells or internal combustion engines to power vehicles or electric devices. It has begun to be used in commercial fuel cell vehicles such as passenger cars, and has been used in fuel cell buses for many years. It is also used as a fuel for the propulsion of spacecraft. Hydrogen is found in the first group and first period in the periodic table, i.e. it is the first element on the periodic table, making it
28038
Period (periodic table)


technetium, the lightest exclusively radioactive element. Period 6 is the first period to include the f-block, with the lanthanides (also known as the rare earth elements), and includes the heaviest stable elements. Many of these heavy metals are toxic and some are radioactive, but platinum and gold are largely inert. All elements of period 7 are radioactive. This period contains the heaviest element which occurs naturally on Earth, plutonium. All of the subsequent elements in the period have been synthesized artificially. Whilst five of these
5268640
De Havilland Comet


rows of seats with four seats to a row installed on its Comets. Large picture window views and table seating accommodations for a row of passengers afforded a feeling of comfort and luxury unusual for transportation of the period. Amenities included a galley that could serve hot and cold food and drinks, a bar, and separate men's and women's toilets. Provisions for emergency situations included several life rafts stored in the wings near the engines, and individual life vests were stowed under each seat. One of the most striking aspects of
13859849
Extended periodic table


that some elements indeed had different properties that break the established pattern, and a 2010 calculation by Pekka Pyykkö also noted that several elements might behave differently than expected. It is unknown how far the periodic table might extend beyond the known 118 elements, as heavier elements are predicted to be increasingly unstable. Glenn T. Seaborg suggested that the highest possible element may be under "Z" = 130, while Walter Greiner predicted that there may not be a highest possible element. There is currently no consensus on the placement of elements beyond
19154578
Period 6 element


row transition metal in group 7 of the periodic table. With an "estimated" average concentration of 1 part per billion (ppb), rhenium is one of the rarest elements in the Earth's crust. The free element has the third-highest melting point and highest boiling point of any element. Rhenium resembles manganese chemically and is obtained as a by-product of molybdenum and copper ore's extraction and refinement. Rhenium shows in its compounds a wide variety of oxidation states ranging from −1 to +7. Discovered in 1925
13470070
Ionization energy


) or kilocalories per mole (kcal/mol). Comparison of "E" of elements in the periodic table reveals two periodic trends: The latter trend results from the outer electron shell being progressively farther from the nucleus, with the addition of one inner shell per row as one moves down the column. The "n"th ionization energy refers to the amount of energy required to remove an electron from the species with a charge of ("n"-1). For example, the first three ionization energies are defined as follows:
14467983