Research suggests that crochet probably developed most directly from Chinese needlework, a very ancient form of embroidery known in Turkey, India, Persia and North Africa, which reached Europe in the 1700s and was referred to as tambouring, from the French tambour or drum.
POLAR BONDS. 1) Covalent bond between two atoms with unequal electronegativities results in unequal sharing of electrons. 2) Unequal electron sharing leads to partially positive and partially negative charges on opposite ends of the bond.When the two atoms involved in a covalent bond both have equal affinity for electrons, the electrons in the bond are evenly shared between them.hese types of covalent bonds are called polar bonds because the electron distribution or charge is unevenly distributed or polarized. Partial charges are represented by lower case delta (+) Î´+ or lower case delta (-) Î´-. A separation of partial charges within a polar covalent bond is referred to as a dipole.
The bonds between carbon and hydrogen atoms are also nonpolar, such as the four CâH bonds in a methane molecule (Figure 2.5 d). In a polar covalent bond , the sharing of electrons between two atoms is unequalâthe nucleus of one atom attracts the shared electrons more strongly than the nucleus of the other atom. When polar covalent bonds form, the resulting molecule has a partial negative charge near the atom that attracts electrons more strongly.