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So in order to explain exactly how individual gas molecules behave, scientists came up with something called a kinetic molecular theory.

Boyle’s Law .txt

And what this theory is is it's basically a bunch of assumptions that they make about gases that helps us understand how individual gas molecules interact.

Boyle’s Law .txt

So the kinetic theory is used to explain the behavior of gases on a nanoscale level.

Boyle’s Law .txt

Now, in order to look at the macroscopic level or explain gas behavior on a macroscopic level, much larger level, we have to look at something else.

Boyle’s Law .txt

Now, scientists came up with different equations and formulas to explain macroscopic gas behavior.

Boyle’s Law .txt

The first formula we're going to look at and discuss is called Boils Law.

Boyle’s Law .txt

Now, Boils Law works under certain conditions.

Boyle’s Law .txt

Now, if we have a constant temperature and constant number of moles or N constant number of molecules, then we can use something called Boils Law.

Boyle’s Law .txt

And what Boils Law relates is it relates volume and pressure.

Boyle’s Law .txt

And what it states is that volume is directly proportional to the inverse of one over P. Or said another way, volume is inversely proportional to one over P. And we can represent this as VP equals constant.

Boyle’s Law .txt

In other words, if we rearrange this and multiply this by some constant, we get this formula.

Boyle’s Law .txt

And what this basically says is that under these conditions of constant temperature and constant number of moles, v times p will always be a constant.

Boyle’s Law .txt

So when B increases, p decreases, or when P increases, V decreases and so on.

Boyle’s Law .txt

And our constant depends on the temperature and the number of moles.

Boyle’s Law .txt

So if temperature increases or its temperature changes or N changes, this constant will also change.

Boyle’s Law .txt

In other words, the number that you get when you multiply D times P will also change.

Boyle’s Law .txt

Now, suppose we have some gas or some sample of gas.

Boyle’s Law .txt

And suppose we have one set of conditions and a second set of conditions.

Boyle’s Law .txt

So suppose I have the following.

Boyle’s Law .txt

Suppose I have some container with pressure one and volume one.

Boyle’s Law .txt

And I have the same container, but with a smaller volume and a different pressure.

Boyle’s Law .txt

So one set of conditions and second set of conditions.

Boyle’s Law .txt

Now, what this law does is it explains macroscopic phenomenon.

Boyle’s Law .txt

Like, for example, why is it that when I take a balloon filled with air and I push it hard enough, it explodes?

Boyle’s Law .txt

Well, why did that occur?

Boyle’s Law .txt

Well, this can be explained by Boyle's Law and I'll show you in a second.

Boyle’s Law .txt

Well, this equation can be rearranged in this format if we're dealing with two different sets of conditions.

Boyle’s Law .txt

Notice that p times V will always give you a constant when you're talking about the same temperature and the same number of mole.

Boyle’s Law .txt

So if I have one set of conditions p one times v one, that will give me a constant.

Boyle’s Law .txt

And if I have the second set of conditions p two times v two, it will give me the same constant, right?

Boyle’s Law .txt

So I can set them equal.

Boyle’s Law .txt

This guy is equal to the same constant that this number represents.

Boyle’s Law .txt

So this is my equation for two sets of data or two sets of conditions.

Boyle’s Law .txt

Now let's look at this picture.

Boyle’s Law .txt

Well, once again, why is it that a balloon explodes?

Boyle’s Law .txt

Well, when the balloon is when you're not compressing the balloon, when you're just dangerous up, it has a certain pressure and a certain volume.

Boyle’s Law .txt

When you take it in your hand and you begin squeezing it, you begin decreasing the volume.

Boyle’s Law .txt

Boils law states that if you decrease volume, pressure must increase because our constant remains the same.

Boyle’s Law .txt

And that means pressure will begin to increase and the ball or the balloon will pop when the pressure is large enough for it to burst open and pop.

Boyle’s Law .txt

And that's exactly why balloon, when squeezed, will eventually pop.

Boyle’s Law .txt

So let's look at ventral sensation.

Boyle’s Law .txt

Suppose that this is our balloon and this is our compressed balloon.

Boyle’s Law .txt

Well, our gas molecule in this condition are further in part than they are in this condition.

Boyle’s Law .txt

And that means if they're further apart here, they will make less collisions than here.

Boyle’s Law .txt

And that means that there are less collisions.

Boyle’s Law .txt

Less of the molecules are colliding with the walls.

Boyle’s Law .txt

And so with less collisions, that means we have less pressure.

Boyle’s Law .txt

So the bigger the volume, the smaller the pressure.

Boyle’s Law .txt

So once again, we see that we can use the kinetic theory to explain nanoscopic or nanoscale behavior of these molecules.

Boyle’s Law .txt

And once again, the kinetic theory explains boiler's law.

Boyle’s Law .txt

A smaller volume means less room to navigate and increase in number of collisions.

Boyle’s Law .txt

This increase in collisions will increase our pressure because by definition, pressure is forced per unit area.

Boyle’s Law .txt

And if we have more molecules hitting the walls, we have more force and so a higher pressure.

Boyle’s Law .txt

So this is Boyle's Law and Boyle's Law is used to explain macroscopic behavior.

Boyle’s Law .txt

So let's examine the graphs of Boyle's Law or a graph of Boyle's Law.

Boyle’s Law .txt

Now, we can have two graphs.

Boyle’s Law .txt

We can graph volume and pressure.

Boyle’s Law .txt

Or we can grab volume and one over pressure.

Boyle’s Law .txt

So let's graph this guy first.

Boyle’s Law .txt

So recall that I said that volume is inversely proportional to one over P. Now mathematically what that means is we have this type of a graph in which as we increase our volume, our pressure decreases.

Boyle’s Law .txt

Or if we decrease our volume, decrease that volume in the balloon, our pressure will begin to increase.

Boyle’s Law .txt

If we continue to increase or decrease the volume, that pressure will begin to increase exponentially, right?

Boyle’s Law .txt

And that's what this represents.

Boyle’s Law .txt

Now instead, suppose that I graph volume over one over P. Well, how would that look?

Boyle’s Law .txt

Well, if I grab the volume over one over P, whenever this guy increases, this guy increases by the same ratio amount.

Boyle’s Law .txt

And that's because volume times pressure gives you a constant.

Boyle’s Law .txt

If this increases by say, two times, then this must decrease by two times.

Boyle’s Law .txt

That's why this guy is a straight line, the slope is constant, versus on this graph, the slope varies, it changes.

Boyle’s Law .txt

And if you wanted to find the slope, you would have to use calculus and approximate it using lines tangent to any point on the line.

Boyle’s Law .txt

Now, this is Boiler's law.

Boyle’s Law .txt

Once again, boiler's Law explains macroscopic behavior gases versus the kinetic theory, which explains nanoscale behavior of individual molecules.

Boyle’s Law .txt

Today we're going to go into detail about atomic structure.

Structure of Atoms .txt

Now, all matter and mass is composed of very tiny units called atoms.

Structure of Atoms .txt

Everything we see, we touch, we feel is composed of atoms.

Structure of Atoms .txt

Now, atoms themselves are composed of nucleuses surrounded by electrons.

Structure of Atoms .txt

Now, a nucleus is composed of two types of particles called protons and neutrons.

Structure of Atoms .txt

Now, protons and neutrons have approximately the same weight.

Structure of Atoms .txt

A neutron is a tiny bit heavier than protons, but for all purposes we can approximate that these guys have the same exact mass.

Structure of Atoms .txt

Electrons, however, have a very small mass, much smaller than that of protons or neutrons.

Structure of Atoms .txt

In fact, it's 1800 times smaller than a proton or a neutron.

Structure of Atoms .txt

Now, if we look at this table and we look at their masses, a proton has one AMU, a neutron has one AMU.

Structure of Atoms .txt

Now, AMU is simply atomic mass unit.

Structure of Atoms .txt

We're going to discuss that in detail in another lecture.

Structure of Atoms .txt

But an electron has a mass of 5.5 times ten to negative four AMU that's much smaller than that of proton or a neutron.

Structure of Atoms .txt

The charge, however, of a proton, an electron has the same magnitude 1.6 times ten to negative 19 Coulombs.

Structure of Atoms .txt

However, the sign of a proton is positive, while the sign of an electron is negative.

Structure of Atoms .txt

A neutron has VR charge.

Structure of Atoms .txt

It's a neutral charge.

Structure of Atoms .txt

Now let's look at the structure.

Structure of Atoms .txt

Now, in the illustration above, we see our atom.

Structure of Atoms .txt

Now, this whole guy is our nucleus.

Structure of Atoms .txt

And our nucleus is composed of two particles, protons and neutrons.

Structure of Atoms .txt

In this atom we have two protons and two neutrons.

Structure of Atoms .txt

The protons are quantitatively charged, while the neutrons are neutrally charged.

Structure of Atoms .txt

Now, the electron is found orbiting our atom, our nucleus.

Structure of Atoms .txt

And the distance between our nucleus and the electron is quite large.

Structure of Atoms .txt

And in fact, atoms are mostly composed of empty space.

Structure of Atoms .txt

And in fact, if our atom with the size of a football field, our nucleus will be the size of a marble.

Structure of Atoms .txt

So you can imagine that our entire atom, for the most part, is composed of empty space.

Structure of Atoms .txt

And that's because our electrons are very, very small and they orbit our nucleus at a very, very great distance compared to the size of the nucleus itself.

Structure of Atoms .txt