Question

Tutorial atoms. protons, neutrons, electrons, basic atomic structure and some fundamentals of bonding. There's definitely a-lot to be said but I wanted to present this in a way that would be easy to read and understand minus the jargon. I used an extension to put in pictures where appropriate to make it come alive.

Answer 1

The basics, every atom contains protons, neutrons, and electrons.

protons and neutrons are found in the nucleus of the atom, while electrons are contained in orbitals, well most likely to be found in orbitals because we can't know for certain both the position and momentum of an electron, but essentially protons have a positive charge, neutrons have no charge, and electrons have a negative charge.

you can see in the figure below for carbon, the electrons will be found in shells/orbitals, while the protons and neutrons are in the nucleus. essentially, the nucleus is positively charged since neutrons have no charge.

Answer 2

You can see for yourself below



Essentially, for an atom let's say carbon, has 6 electrons. Remember every element in the periodic table is electrically neutral. what does this mean? it means that every element has a neutral charge because the number of electrons = the number of protons.

so in our atom above, carbon, it has 6 protons and 6 electrons. now, depending on what happens, the number of electrons can change, atoms can lose or gain electrons based on their reactivity and also how many valence electrons they may have. we're going to get into this shortly.

Let's look at what happens when the number of electrons changes.

let's look at fluorine atomic number of 9. this means that fluorine has 9 electrons and 9 protons. remember when reactions happen the number of electrons can change but usually the number of protons stays the same, unless we're dealing with some kind of nuclear decay, but essentially fluorine still stays fluorine when it gains an electron.

essentially if you look in the figure below, fluorine gains one electron, so before now we have a situation where flourine has 10 electrons now and 9 protons. this means that now it carries a net negative charge -1. see below in the figure. There is a name for this an ion with a negative charge is called an anion

see below. Comparing these two we can see that the number of electrons changed. we will get into this shortly as to why this happens.



now, here's an example of a cation. Some elements like to lose electrons, which I will get into later. they like losing electrons because they can get closer to achieving octet, a very important concept. but, Just take a look at what's happening below.

let's take a look at lithium, atomic number 3 which means it has 3 protons and 3 electrons. now lithium, will lose an electron so the lithium ion will have 2 electrons and 3 protons. now there are more protons than electron, so the net charge will be positive +1. The result here is a Cation.

Take a look at this below:



Now the most straight forward way to explain cation and anions is this:

Metals like to lose electrons like Lithium while
non metals like fluorine like to gain electrons.

This is really the foundation behind metals and non metals, but there is another issue I will touch upon.

Also, remember that the atomic number = the number of protons/neutrons usually written at the bottom while, The mass number is the number of neutrons and protons in the nucleus denoted on top.



say if we had helium, the bottom number tells us that there are 2 electrons and 2 protons in our helium atom. right?

now look at the top we see the number 4.

If we subtract the mass number 4 from the atomic number 2 we get the number of neutrons which is 2.

Simple little formula here mass number Z- Atomic number A; Z-A

Answer 3

The basis of this is that elements will differ in the number of neutrons they have and that's called isotopes. The numbers you get on the periodic table for masses of the elements are actually a weighted average of all the naturally occurring isotopes. In every day language it's just the average of the isotopes that occur the most often.

Check this out below:

look at carbon, and the isotopes that it has. it's still carbon because it has 6 protons but the number of neutrons will be different. actually the way that I like to think about it is that the number of protons is the finger print or the identity of our element, because those are in the nucleus and we usually can't get to them. electrons move around, which i'll get into that but take a look at the concept of isotopes, their just different flavors of carbon with different #'s of neutrons.

Answer 4

The next thing I want to touch upon is the periodic table. Naturally there are three groups. metals which want to lose electrons, non-metals that want to gain electrons, and metalloids that have properties of both metals and non metals.

If you notice, the elements are organized into groups and periods. groups are vertical, and they are called families, they are organized by the same number of valence electrons. I'll get into this, this is very important.

periods are horizontal and those usually have the same number of shells. "Also i'll get into this too".



but there's something even more important, i said two things before:

Metals like to lose electrons
While non metals like to gain them?

Why?

The types of bonds elements make are what determine their reactivity as well as how many bonds they make as well. this all has to do with in what vertical column, group our elements are in the periodic table are.

In-fact, elements want to have a filled valence shell. what does this mean?

The valence shell is the last, outermost shell in our atom. that's where all the chemical reactions are happening. one thing i forgot to mention.

The nucleus is postiively charged right?

so what's going to happen is that the nucleus is going to be pulling the electrons because they are opposite, think opposites attract.

the closest you are to the nucleus, the stronger the pull. the farther you are from the nucleus the less these electrons will be pulled because they are farther away.

in-fact something that happens is called shielding. the electrons in the outermost shell are shielded most from the pull of the nucleus because they are so far out.

let's take oxygen for example, take a look at it. look at the valence shell. oxygen has 6 electrons there, so it's going to need 2 more to achieve something we call octet.

In-fact octet means that in the last shell, there are 8 valence electrons, OR the outermost shell is filled. This means that the element is happy and wont react further.



Let's look at this again. The electron(s) closest to the nucleus in oxygen are going to be held most tightly by the nucleus and thus harder to move.



the electrons in the valence electrons are not going to be held as tightly as the electrons that are close to the nucleus.

All elements would love to have a filled octet of 8 electrons, or something like it. so they will react accordingly.

here are the noble gases in group 8, they are largely un reactive because they are happy with the 8 valence electrons in their outermost shells.

metals and non metals will form different types of bond to try to achieve octet.

Answer 5

This leads me to the next topic up for discussion.

Some definitions:

Aufbau principle = we build up meaning we put in electrons in the lowest energy levels first. also we take out electrons from the highest energy levels first, makes sense because farther away from nucleus means easier it is to take out electrons.

Hunds rule, when we put in electrons we put them in either all spin up or spin down.
TRANSLATION each electron is an arrow, and spin up means you draw the arrows pointing all up or down.

paulis exclusion principle: when we don't have enough electrons to fill the orbitals we try to make sure that each orbital has one electron.

There are other things that we have to consider too.

Remember in the beginning, I said orbitals are places where you can most likely find electrons; well yep; they come in different shapes too. also the periodic table is based on this.

Some more definitions the principle quantum number n = the energy level. the columns on the periodic table are the principle quantum numbers.

l = the shape of the orbital

mL = the orientation of that orbital it can go from +L, to -L but is never greater than L.

Ms = the spin, that's if the electron is +1/2 spin up or -1/2 spin down.

there are four types of orbitals

s orbital holds 2 electrons, only 1 orientation so L = 0, mL = 0, starts at n = 1
p orbital holds 6 electrons, three orientations so L = 1, mL = 0,+1,-1, starts at n =2
d orbital holds 10 electrons, 5 orientations, L =2, mL = 0,+1,-2,-1,+2, starts at n =3
f orbital holds 14 electrons, 7 orientations, L = 3, mL =0,1,2,3,-1,-2,-3 starts at n =4

This is how the periodic table is organized remember when we put in electrons we always put them in starting at 1s, then 2s, 2p, 3s, 3p, in that order until we've filled them completely.

Answer 6

Let's look at the different orbital types I didn't show f orbitals because usually in an intro course they don't really talk about them, maybe they do lol just not the course I took.