# Structure of Atoms

A neutral atom consists of an extremely dense nucleus and so we see this nucleus right here and it’s going to be composed of one or more positively charged protons.

I’m just going to draw a circle right here and put a P in the middle, so that’s going to stand for proton. This middle circle here represents the nucleus, it’s going to be really dense, okay.

Mini-test: STRUCTURE OF ATOMS

Question 1: The nucleus of an atom contains the atom’s
A.
B.
C.
D.
Question 2: The electrons of an atom are organized into
A.
B.
C.
D.

The next lesson for you: States of Matter; these lessons are included in the practice tests.

[divider]The following transcript is provided for your convenience.[divider]

It’s made up of these positively charged protons and then inside this nucleus, there’s also going to be a varying number of uncharged neutrons and that exists in every atom, except for hydrogen one. I’m going to go ahead and draw some more circles, I’m going to put it an N in there for neutron and notice they’re connected to the protons. Now there’s going to be a cloud of one or more negatively charged electrons outside of the nucleus and so the number of electrons is going to be equal to the number of protons.  I’m going to draw some circles with an E in them to represent electrons, so we have three protons in there, so it’s going to be three electrons.

Now say there are four protons and there’s going to be four electrons out here. Now there’s a bond between the protons and neutrons, they’re bound together by a strong nuclear force and so this force is stronger than the repulsive force between the positively charged protons. All these protons are positively charged, so we’re going to put a plus symbol and so positive charges or liked charges wants to repel away from each other. But the bond between the neutrons and the protons are stronger than the repulsive force between the protons and neutrons, by the way, have no charge, they’re not positive or negative, they’re uncharged.

Now the negatively charged electrons, which are out there, these, are negatively charged, so I’m going to put negative symbols. These negatively charged electrons are attracted to the positively charged protons by the electromagnetic force and so all these electrons are attracted to the protons that are inside. Now remember earlier I said there has to be the same number of protons as there are electrons. The reason for that is because this is a neutral atom, meaning it has no charge and so the four positive charges that we have here cancel out the four negative charges we have.

Let’s say we have four positive charges and we had seven negative charges then this atom would have an overall negative charge, but that’s not the case because there is the same amount of positive and negative charges, the atom as a whole is neutral. The number of protons determines the identity of the chemical element, while the number or electrons in the outermost shell determines the ways in which the atom interacts chemically with the other atoms or molecules.

This is the shell right here outside of the nucleus and sometimes there are other shells in this case, it’s just one and so the number of electrons in this outermost shell, determines the ways in which the atom react chemically with other atoms or molecules.

The next lesson for you: States of Matter; these lessons are included in the practice tests.