Question

Basic Tutorial chemical bonding

Answer 1

:D

Answer 2

thanks, in advance

Answer 3

I'll explain this in a straight-forward manner, for an absolute beginner.

minus the fluff and jargon.

In every atom, we've got a nucleus with protons positively charged, neutrons with no charge, and electrons that are negatively charged.

within the nucleus, we've got protons and neutrons, and so this makes our nucleus of the atom positively charged.

outside the nucleus, electrons are negatively charged. the closer the electrons are to the nucleus, the more tightly they are going to be held, because think about if. the closer you are to the nucleus the more tightly the electrons are going to be held. remember opposite charges attract one another. the farther you get from the nucleus, the less tightly your electrons are going to be held. This is a very important concept when it comes to bonding.





A chemical bond occurs when electrons are shared between two atoms. i'll get into this more later. Think about it this way, the electrons are basically the glue that holds the molecules together.

Answer 4

if you're wondering about how I was able to put images into this, you can thank @Jaynator495 for his extension.

Answer 5

@Photon336

"within the nucleus, we've got protons and neutrons,"

AND QUARKS! Don't forget about them!!! (Ignore unless you are in particle chemistry, lol)

But for reals though, this is very nice! :D

Answer 6

What I said before is important because the farther we get from the nucleus, we have something called shielding that takes into effect. Shielding, is a fancy way of saying, that the inner electrons, shield the outer electrons from the positively charged nucleus. or in more blunt terms, the farther away you are from the nucleus, the positive charge loses more of its pull on the electrons.

Think about the solar system. mercury is the closest to the sun right? so it's the hottest, while pluto is the farthest from the sun and is the coldest. think about it in that way.

Take a look at sodium. the look for the circular looking path almost orbit that's the farthest from the nucleus and count the number of electrons in that.

This becomes important because as we get out even farther, or say. the shell where the electrons are farthest from the nucleus, there is a special name for this. This is called the valence shell. don't worry about "shell", just know that these electrons are highly important because that is where all the chemical reactions take place.




see if you can identify the valence shell. and the number of electrons in it.

Answer 7

@alphadxg yeah didn't want to scare people away they'll say QUARKS what are those??!

Answer 8

Now, that we have identified the valence shell. here's one very important thing.

The valence shell holds 8 electrons:

now

EVERY ATOM wants to have 8 electrons, and will gain and lose electrons to do so, this is basically the foundation of chemical bonding.

Atoms will gain or lose electrons to achieve octet and this partially depends on a concept called electronegativity which i'll go into later.

What happens when you have an element with a filled shell or 8 electrons in that shell?

something interesting happens. the noble gases are kind of our celebrities, reclusive and selective about who they let in, and they virtually don't react with anything.

they are called inert gases, and in organic chemistry we often will inject an inert gas into our reaction.

now at the most basic level they don't react because, WELL, THEY DONT NEED TO!






for those of you interested, there are some interesting compounds that can form with noble gases, the majority of which are with an element called fluorine. I'll explain why.

we've got xenon hexafluoride. look at that!



it's really an exception just to show you that, "exceptions do exist" and you shouldn't just blindly memorize stuff.

in fact fluorine is so reactive that it will react with virtually anything, I'll show you why in a bit.



In all the most important take away is that, ALL elements will form bonds to try to achieve an electron configuration similar to one of these golden noble gases. they will either lose or gain electrons to achieve octet.

Answer 9

The next most important concept in bonding depends on a concept called electronegativity.

electronegativity is in blunt terms:

"HOW BADLY DOES THE ELEMENT WANT THAT ELECTRON?"

The higher the electronegativity, well the more we will expect that an element will want to have an electron.

now let's take a look at electronegativity on the periodic table trends.

the vertical columns are called groups while the horizontal groups are called periods.

Take a look below:

This will help you to identify what a period is and what a group is.



Now, check this out: what happens is that generally as we go across a period
electronegativity increases, while as we go down a group electronegativity decreases.

simple right? Wrong.

don't just memorize this. this means nothing if we can't understand why this trend exists.

Answer 10

Let's explain electronegativity down a group first.

as we go down a group the vertical columns on the periodic table, the number of shells increases, or IN Other words the ATOMS get bigger.

another way of saying this is atomic radius, and it means just what you may think it is. try to take a look at the figure below.



As we go down a group, what happens as we said before is that the outer electrons become shielded from the positively charged nucleus by the inner electrons. Remember what we said before?

they not only less tightly held as you go down a group but also easier to remove, I.E. ionization energy.

in actuality, the electronegativity decreases as you go down a group.

Answer 11

Now let's try to see what happens as we go across a period.

Answer 12

As we go across a period take a nice look at what happens. See something interesting?

If you notice the atoms are getting smaller, i.e. atomic radius is decreasing.

Also the number of shells isn't increasing either.



What happens is that as you go from left to right across a period, you add an electron and a proton right?

but what happens is that the number of protons increases, and that's a fancy term called the Zeff z effective nuclear charge.

which means that the positively charge of the nucleus is getting bigger and is thus HOLDING the ELECTRONS more and more tightly as we go from left to right.

so what happens is that this actually accounts for why the electronegativity increases across a period.

Question:

which atom would you expect to be more electronegative and why?

Fluorine or Lithium and why?

Answer 13

Now, these concepts are actually important because if you can identify the electronegativity of an elements in a bond it's actually a good way to help you determine the type of bond we have. Now i'm going to get into this.

Answer 14

Now remember we said that elements will either gain or lose electrons to achieve octet?

well as we've discussed this depends on electronegativity.

now let's classify our elements into categories.

Metals/Nonmetals/and metalloids.

Please look at the figure before going forward.



Now basically, I won't get into this in very much detail about properties we're only concerned about bonding.

When comparing metals and non metals pay attention to the following this is the foundation:

Metals like to lose electrons to achieve octet and have lower electronegativities.

Non-metals like to gain electrons to achieve octet and have higher electronegativities.

Answer 15

Question:

can you classify these two elements

Iodine I
Lithium Li

then compare their electronegativities which one is higher?

then justify whether which one would be more willing to gain or lose electrons?

Answer 16

Well I guess if you are interested in knowing about metals,

I.E. transition metals are from groups 3-12.

Honestly I think the stuff about the metals and their physical properties is not really important it's better to visualize their properties in a lab.





They are responsible for color :)




There is more variation in non metals in their physical properties.

Look at bromine a liquid at Room Temperature



Here's iodine, it's a solid at Room Temperature.

Answer 17

Now that we have made it through this, the next step is to get into what bonds are.

Now electrons can either be shared, or transferred.

If they are shared between atoms, then the bonds are covalent.

Now remember what we said about electronegativity? the greater the difference in electronegativity between the two atoms the electrons are going to spend more time near the element that has the higher electronegativity.

if there is an electronegativity difference, we call it polar covalent.

if there is no electronegativity difference its non polar.


Let's look at non polar covalent:

Remember if there is no electronegativity difference its non polar.

this could mean two things:

1. The first is that all the atoms have the same electronegativity
2. The second means that there is no net dipole moment.

Let's look at the first example of non-polar covalent bonds.

Let's take Chlorine gas. Cl2 both atoms have the same electronegativity, and second they need 1 electron each so they've got to share them.

because they have the same electronegativity, it's non polar.



take a look at it again



Now Question for you let's look at this molecule: CF4 is this non polar or polar?

You would think Yes because well, fluorine is electronegativte. WRONG. it's not.

here's why.

there's something called a dipole moment. meaning for a molecule to be polar, the electrons have to all be pointing in one particular direction. that's the best way I can explain it.



When we look at CF4 notice all the dipoles cancel out. there is no net negative charge. our flourine atoms are all pulling electrons in different directions, and they cancel out.





Now the second example is called polar covalent.

A molecule is polar when it's got a net dipole moment, meaning that the electrons tend to be drawn to a particular part of the molecule.

let's take water for example: water has 6 valence electrons and is an non-metal. from what we know it's got a high electronegativity much higher than hydrogen. so the electrons shared from hydrogen are going to spend more time near the oxygen. so this gives us a net dipole, all in all the electrons want to be near oxygen.

this is what we mean by polar, and covalent.




now check this out usually covalent bonds happen between a non metals.

there is another type called coordinate covalent bond. This happens when both of the electrons come from the same atom.

usually in covalent bonds one electron comes from one atom, while another electron comes from the other. this is the same if you've got double and triple bonds.