IONISATION ENERGY

Now, everyone this is where I get really EXCITED - you'll see the connection later - as this is my favourite part.

Plasma is a super heated gas that has become ionised. This means that the electrons have enough energy to break from their shell and move around (though they don't fly off into distance). 

Though now we're getting into the physics field so I have to be careful as some chemists simply dislike physics (God knows why - Physics person myself).

You may be asking what has all of this got to do with ionisation energy? Good question, not much, well maybe a little. 

Ionisation energy is the energy required to remove 1 mole of electrons from 1 mole of atoms in a gaseous state.

In a plasma, electrons get freed but they need some energy to get excited (there now - get it) and leave their shell. This is the ionisation energy though in this case the electrons get removed from the compound completely to form an ion. So unlike in a plasma where the electrons swim in a "sea" surrounding the positive ions (like in a metal) during ionisation the electron is removed to produce an ion.

The ionisation is influenced by three main factors:

• Nuclear charge: As it increases the attraction on the outer electron increases so ionisation energy increases.
• Electron shielding: As the number of shells increases the ionisation energy decreases as there is a weaker attraction on the outer electron.
• Atomic radii: The further away an electron is from the nucleus (so the greater the radius) the easier it is to remove it as the attraction of the nucleus on it is much weaker, so ionisation energy decreases.

Electrons exist in shells AKA quantum levels. Each shell is made from different sub shells. Each sub shell contains only the same type of orbitals and each orbital can only hold 2 electrons of opposite spin.

ORBITAL: A region that can only hold 2 electrons of opposite spin.

SUB SHELL: A group of the same type of atomic orbitals within a shell.

SHELL: A group of orbitals with the same quantum number.

If we now image one electron as a cloud, as it very difficult to know the exact position of an electron we will just assume that the electron can be anywhere within that cloud. This an atomic orbital. If we have two electrons, we don't have two clouds (or regions where the electron can be) - it's one orbital but twice as dense.

Those clouds - orbitals - can take various shapes, when they overlap even stranger things happen. Remember the orbitals are 3D and you do not need to know all the orbital shapes only these:

• S - Orbital: Spherical in shape. Each shell contains only one s-orbital therefore in one shell this gives a total of 2 electrons.
• P - Orbital: Dumb bell shape. There can be up to 3 p orbitals in each shells so a total of 6 electrons.
• D - orbital: Up to 5 orbitals in each shell. Total of 10 electrons in a shell.
• F - Orbital: Up to 7 orbitals in each shell. Total of 14 electrons in a shell.

This is a scary overview of how all the combinations of orbitals look. Below are the shapes you actually do need to know.

Lastly you may need to give an electron configuration so use your periodic table to correctly identify the orbitals and the number of electrons in a shell. Also remember that the 4s orbital is filled in first before the 3d orbital. The 4s orbital is also emptied before the 3d orbital. This is because the 4s orbital has a lowe energy level thatn 3d.

Let me give you a couple of examples:

O: 1s2 2s2 2p4

CA: 1s2 2s2 2p6 3s2 3p6 4s2

Fe: 1s2 2s2 2p6 3s2 3p6 4s2 3d6

Here are some rules to help you get your head round it all (it is a very confusing chapter but you'll be all right. 

• Electron fill in the lowest energy level first.
• Each orbital is filled with a single electron first before pairing starts.
• When two electron enter the same orbital they must have opposite spins.

Its like old ladies on a bus, they will fill in from the front first and sit on separate seats and when all have been filled singly then they sit next to someone else.

REDOX

Now to tackle one of the hated parts of chemistry, unless you are a maths Genious (high five!) or love chemistry so everything's dead easy for you anyway.

REDOX

Thought this may seem useful for you guys. Seems very AWESOME actually.












In REDOX reactions some things will get OXIDISED and some things  will get REDUCED.
Oxidation is the loss of electrons and reduction id the gain of electrons.My friend finds it very easy to remember which one is which by this very simple mnemonic OIL RIG.

O: Oxidation
I: Is
L: Loss

R: Reduction
I: Is
G: Gain

I simply think about it, reduction means go down so the charge (oxidation state) will get more negative therefore reduction id gain of electrons. So now you know oxidation is the opposite.

You all have different memories so pick and chose.

There are some rules which you will have to memorise in order to help you in the exam to remember how to work out oxidation states. Remember when it even mentions REDOX or reduction or oxidation you'll know which guns to take out.

Group 1: +1
Group 2: +2
Group 7: -1
Oxygen: -2, Unless it is Hydrogen peroxide then O: -1
Hydrogen: +1, unless it is metal hydrides then H: -1
Transition metals: You will be told in the question, it will give you a Roman number.

An element on it's own has a oxidation number of 0. And unless a molecule has a charge on it then the oxidation states of the atoms within MUST cancel out.

Now something to calm you down:

• Metals form + ions so they lose electrons. They get oxidised as their oxidation number goes up.
• Non-metals generally form - ions so they are reduced because they gain electrons and their oxidation number gets more negative.

ACIDS

Now ladies and gentlemen, things are going to get very Factual so get your notepads out and shift your brains in gear for its time to memorise some definitions.

Oh and here's a very awesome cat I found.



As I'm sure you're all aware each acid contains a H+ ion. Sounds familiar?? I hope so. Then what an acid is should also click into place: Acid is a proton donor. Which just means that in a reaction the acid will give up its H+ ion to swap it for something else. And what is a H+ ion, well it's just a proton all by itself.

You are also expected to name some common acids and know their formulae. So I've made this easy for you and listed them here:

Hydrochloric acid: HCl
Sulphuric acid: H2SO4
Nitric acid: HNO3

The opposite, or the counterpart of you will, of an acid is a base. And also have to know some bases:

Metal oxides: MgO
Metal hydroxides: Mg(OH)2
Ammonia: NH3

These, I'll tell you straight away, can be used to neutralise acidic soil because when you add acid to base in the right amounts you produce water or a neutral solution and salt.

An Alkali is a soluble base that releases OH- ions in an aqueous solutions. So whereas an acid releases (donates) a H+ ion and alkali donates a OH- ion.

When an acid and alkali react together in the correct amount a neutral solution is formed, like I mentioned above. However a salt is always formed. A SALT is produced when the H+ ion is replaced by a metal ion or NH3.

You need to also be able to explain that a base accepts H+ ions from an acid (like I said a couple of times). For example:

• OH- and H+ ions give H2O
• NH3 and H+ give NH4+ ion.

There is also another part to acids that you may hate, or love depending on your view point of Chemistry and maths in general. It is water of crystallisation. When a crystal forms (salt) there is bound to be some water molecules locked up in there this a hydrated salt. An Anhydrous salt is a salt without water.

To work out the water of crystallisation you need to:

1. Work out mass of the hydrous and anhydrous ( or you may be given them).
2. Take them away from each other. This will give you the mass of the water.
3. Now work out the moles of water and the anhydrous salt (using the triangles that you have learned).
4. Once you have the moles divide both values by the smallest one, this will give you the ratio of anhydrous salt to water.
5. Ta dah! You have worked out the water of crystallisation. The value of the ratio for water is the answer. Stick that in front of the water and BOOM!
6. Make sure you have a DOT "." before the H2O to ensure that this is a water of crystallisation and not some crazy molecule you just came up with.

MOLES and EQUATIONS

Don't worry this part of the course isn't about actual moles:

Though I'm sure I'll find someone here who will go: Awww, why not ^_^ (Sorry)

When talking about a mole of a substance you can't think about furry little atoms that dig underground all their life, it doesn't work like that, again sorry ^_^

A MOLE of a substance can be explained in many different ways.

• Amount of substance
• The Avogardo's constant (sound cool, doesn't it - you'll learn to love and hate it soon) 

If we take IRON with molecular mass of 55.8, for example, the amount of 1 mole of iron would be 55.8 grams. See the connection yet??
Okay, 1 mole of Xenon (why not??) with molecular mass of 131.3 is 131.3 grams. Well... Isn't this magic? Its not, sorry so many disappointments.

Now you may ask if we have 3.5 moles of something how much is that? Well, you might have figured that out already that you'd multiply the molecular mass by 3.5. To make life easier this is the formula:

Now, when talking about Avogadro's constant life gets so much more interesting. A mole of ANY substance contains exactly 6.02 × 10^23 mol-1 particles.

You may also need to calculate concentrations and volume of aqueous solutions so here is another triangle, which is pretty much self explanatory - find what you need to work out, see what you've got,, find the right triangle and then your best friend calculator will do the rest.

Examiners also like to put another type of calculation just to throw you, so watch your units!! You may have to calculate the gas volume of, well, a gas.

 

Remember that 1 mole of gas molecules will occupy 24 dm^3 at room temperature and pressure.

Well, that's pretty much it at the moment, I mean when it comes to moles it does. Oh, I would have forgotten completely (my chemistry teacher would kill me if I didn't say this). 

REMEMBER ABOUT STOICHIOMETRY. 

Sounds gibberish? Well all it means is always look at the ratio of moles in the equation you'll be given.

Now for those Linkin Park fans out there: In the end it doesn't even matter cos you know it all, so when they come for you with those equations you'll not be Powerless any more.

ATOMS

To start of with you need to get your head round all the basics. I have a list of all the spec points that you need for the exam and I will try and go through them as easily as possible, but lets start at the beginning first.

Everything is made up of atoms, you know that, right? But the real question is what are made up of, for it definitely cannot be something "indivisible" as its name suggests. Well, it's not.

An atoms is made up of essentially two "parts", if you don't mind me putting it that way. The centre of the atoms is the NUCLEUS of positive charge, this is because it is made up of protons with +1 charge and neutrons, which are neutral. Now the atom itself is neutral so you need something to cancel out the charge. Dead easy, electrons -1 negative charge, which exist in shells around the nucleus.

A proton and neutron both have a relative mass of 1, whilst the mass of an electron is very small: 1/2000 of a proton. That's relative mass, for those more interested in actual numbers, the mass of an electron is actually 9.11 × 10-31 kg.

The number of protons (atomic number) in a nucleus is equal to the number of electrons in that atom - the charges have to cancel out.

The term ISOTOPE means an atom of an element with different number of neutrons and different mass.

It is also important to note that all relative masses are compared to the C12. Hence the definition of relative atomic mass is the weighted mean mass of an atom compared to one 12th of carbon 12 atom.

When given the abundance of the isotopes of an element, the relative atomic mass is easy to calculate. First multiply the mass by the abundance. Add up the different values. And divide by 100.

Overview of Y12 Chemisty

The year 12 course consists of:

• F321: Atoms, bonds and groups (which is made up of 3 modules - they're pretty cool actually, though you do need to do a bit of memorising).

• F322: Chains, energy and resources (which is made up of 4 modules, more then F321 but you get extra time in the exam - it's a big paper).

Important to note that all the pictures belong to their respective owners. I do not own any of those pictures. All the information has been put together to prepare for my exams and to hopefully help some of you as well.

Enjoy and may the luck be ever in your favour - in your exams.