Naming compounds and finding formulas

Are you called Xavier? I envy you.

Thought it might be a nice break. Back to work though. Scientists... For naming compounds they stick to 2 simple rules. What do we even pay them for? Maybe it's enhancing our lives and stuff. Who cares.

Rule 1:

When two different elements combine the compound's name is "something-ide".

So, if sodium and chlorine combine, you get a compound called sodium chloride. How inventive he said cynically.

Rule 2:

When three or more different elements combine and one of them is oxygen. The compounds name is "something-ate".

Really need an example? Copper, sulfur and oxygen combine to make copper sulfate.

SO:

• 2 = ide
• 3+ = ate

Now the difficult bit! 

Finding the formula

You have to balance the charges:

If you look closely... they're not real children

So if you have 22 positive charges, get 22 negative charges. If you have a magnesium ion that has a positive charge of 2 then you need an ion that has a negative charge of 2 or 2 ions with a negative charge of 1. If you like the maths side then see below... and you're probably single but that's not the point.

2 (positive charge) - 1(negative charge) - 1(second negative charge) = 0

SO 2 - 1- 1 = 0 

OR 2 - 2  = 0

All done.

 

Ionic Compounds

Ionic Compounds

Ionic compounds... what results from ionic bonding. Can you even get that wrong?

Shown in dot and cross diagrams... Not sure I need to explain that... But have a picture!

Sodium gives up it's dot to chloride.
A horrific robbery.

If you don't understand that, it's simple. The dot is on the outer shell of the sodium and is all alone. So sodium tells it to shove off and it joins the nearly full chloride outer shell. That is the red dot next to the crosses.

Ionic Compounds

You need to know a few things... Why? Because it's on the syllabus you idiot.

• Ionic bonds always produce compounds with similiar structures
• The ions form a closely packed regular lattice arrangment (Don't worry, there's a picture)
• Ionic bonds are very strong electrostatic forces of attraction between oppositely charged ions.
• "You what?" Opposites attract right? That's all it said.
• Ionic compounds all have similar properties due to their structure (e.g. Sodium chloride and magnesium oxide)

There's your lattice.

Now this stuff is key, you don't learn it, there's gonna be a train wreck.

• HIGH MELTING POINTS and BOILING POINTS

This is due to the very strong bonds between the ions. Takes a lot of energy to break these bonds. Like 2 lovers in embrace, you can't break them apart. *insert lonely here*

And:

• They conduct Electricity when aqueous and molten.

Dissolve them in water and the ions all scatter around like kids in a swimming pool. This means the ions are "free to move". This means they can carry electric current. If an ionic compound is melted then the same thing happens. Not like children... because they'd have melted. And that's bad parenting.

Ionic Bonding: That one night stand

Probably don't understand the title. When we get to "clingy girlfriend" covalent bonding you will.

Ionic Bonding

It's a hot night on the dance floor, that booty rocking. You're just a small town cation, looking for a lonely anion. You find one, success. Walk over and say "Hey, how's it going?". She flutters her eyes at you... Her shells so nearly full. "I'm looking for something... Think you got it?" Oh, you just can't wait to give it to her. You can already feel the chemistry. "I got it, but nothing more and nothing less." You take her by the shell and take her home. You can feel the heat between you. You show her what you've got and she returns the favor. She has so much more than you, but that's how you like it...

A few seconds later and it's all over, you've given her what you had and can give her no more. Both satisfied and both full.

Well, that story was odd... Very odd. And never again will I Google images "Bonding sex" .But the purpose was simple. Ionic bonding is the losing of an electron. He has one electron in his outer shell and she needed one, he gave her all he had. Simple stuff. The difference between this and covalent bonding (covered in another article) is that she just left. She wasn't clingy, she was fulfilled.

Oh look, it's Covalent bonding girl.

All this sexual imagery... let's get back to science. Groups one and two are "Cations" and groups 6 and 7 are "anions". Cations and anions are most likely to form ions.

The Periodic Table: Some Facts

Metals                                                                                                                                   Non Metals

There's the first point. Worked? Metals are on the left hand side of the table whereas non metals are on the right. Seems too simple... Well that's still a third of this topic already.

Arrangment of the periodic table

Periods:

Read from left to right. Like a book. 

If you laughed at the word periods...

There are 7 periods in total.

Groups:

Looking from up to down. How you might check out a hot, extraordinarily tall, girl at a club. Or guy, can't be exclusive now can we.

The groups go up to the number 7. "What are you on about you idiot? Good job you don't do a maths blog." Thanks for the feedback in anticipation. Oddly enough it goes from group one on the left hand side (shown in red) to group 7 on the right hand side (shown in dark blue). And then the purple group just appears out of nowhere being names group 0! How odd.

See, this chemistry stuff isn't hard? 

• Metals on the left
• Non metals on the right
• Periods like a book
• Groups like a very tall attractive person

The periodic table: A written documentary

1800s:

"What the hell does an atoms structure look like? Let's just put them in order of relative atomic mass!" 

And then...

"Wait a second lads! Some of these elements have the same properties! We need someone to sort them..."

Who's the man for the job? Mendeleev. Chemistry LAD.

Creepy Russians...

1869 Mendeleev:

 "Put the ones that are similar together in groups. But there seems to be some gaps..."

So, what would any distinguished scientist do?

"Let's take a stab at predicting them! What can go wrong?"

Surprisingly... Not much. Mendeleev was correct in his prediction of many of the elements that were missing. The periodic table you see today is not the same as it once was but it has simply been refined.

 

 

Isotopes and relative atomic mass

First half of this, easy. Second half... maths. It's all just smoke and mirrors.

Learn this definition and that is the topic covered, easy stuff!

"Isotopes are: different atomic forms of the same element, which have the SAME number of PROTONS but DIFFERENT numbers of NEUTRONS."

For safety sake I will explain it. If something has 8 protons in its atomic number it should have 16 in its mass number. If it doesn't? DING DING DING. Those alarm bells. Could be an isotope.

Here comes the hard bit...open wide! Well that sounded a bit sexual. Moving on... The "Relative atomic mass" takes Isotopes into account. What a nice guy. You need to know 3 steps because they will give you the figures you need in the exam:

• Multiply the mass of each isotope by its relative abundance.
• Add those together
• Simply divide by the sum of the relative abundance.

I nicked this picture straight from the revision guide:

If you can read it, learn it.

Elements

Elements

Learn this definition it should be just fine:

"Elements consist of ONE TYPE of ATOM only"

So what makes elements different? It's how many protons it has. So, take helium for example. Helium has 2 protons, so any element with 2 protons will be helium. It gets no choice in this. *whip noise*

Every element has these 2 things, learn them:

Mass Number:
The number at the top left of the element. This tells you the total number of protons and neutrons in the atom.

Atomic Number:

The number at the bottom left of the element. How many protons are in the atom? That's what this number tells you.

So in summary:

Top number = number of protons and neutrons. (mass number)

Bottom number = Number of protons. (atomic number)

Since I didn't put a picture in, have this one:

That cat be lovin'.

Electron Shells

Electrons

Electrons occupy shells. *insert crap turtle joke*. These shells are what the electrons orbit the nucleus on. Simple. Fills the lowest energy cells first, then the larger ones. Might seem a bit confusing...

So the amount of electrons that can fit in a shell goes in this pattern:

2,8,8

You actually don't need to know any further than that. Good isn't it? So, 2 electrons in the first shell, then 8 in the next and then 8 in the next. Can it get any simpler? Well I can try. If you had a doughnut and it had jam in the middle it would start in the middle and go outwards. No one want to find the middle without jam, you do? Freak.

Ignore the extra 2. No one cares about it.

So the electron shells fill up from the closest shell that can fit 2 electrons to the outer shells that can fit 8. The name for this is "Electronic Configuration". You do need to know this, don't start slacking now.

In the exam, that word hurts so much, you might be asked to draw or work out the electronic configuration of any of the first 20 elements in the periodic table. Sure, you could spend all that time learning them off by heart or just keep it simple like this:

Let's take Magnesium. It has 12 protons. 12 protons = 12 electrons. So 2 in the first shell, that leaves us with ten and then 8 in the next and that leaves us with 2 and 2 in the final, but not full, shell. 

The electronic configuration of Magnesium is: 2,8,2. 

OR

2,8,2

So, simple stuff.

Atoms

Atoms

Simple as that. The nucleus has both neutrons and protons. Simple stuff isn't it. Those little dot things surrounding it are the electrons. How adorabubble. 

You need to know a few things about these. 

Nucleus: 

• MIDDLE of the atom. 
• Not the left, not the right but the middle.
• Positive charge.
• Nearly all of mass in the atom.

Electrons: 

• Orbit the nucleus. (   .   ) Like that. That's right... laugh at the boob, hilarious.
• Negative charge.
• Size of orbit determines how big the atom is.
• VIRTUALLY NO MASS. Bit like some of those models you see nowadays... Disgusting.

Number of protons equals number of electrons.

Learn this table, it's vital:

You learnt it? Well you should have done.