Reduction!!!

OK, so carbon has some great properties, it can reduce metallic oxides to the metal with CO2. Here are some reduction reactions:
2CuO+C------>2Cu+CO2

2ZnO+C------>2Zn+CO2

 2PbO+C------->2Pb+CO2

2FeO-------->2Fe+CO2  


 The figures are similar to then manufacture of oxygen using heat, where instead of KClO3

We put the metallic oxide and carbon together.
Adios!      

We start physics...

OK physics I would like to say is a wonderful subject.
(Teachers who make physics boring are criminals -walter lewin)
So to begin I would strongly recommend that you ask questions like a baby does how, why, if and so on, it is the main thing that drives the world.
Let's begin by talking a bit on quantities.
What is a quantity? Well a quantity is anything that is there to tell about something.
We are mostly interested in physics in Physical Quantities. So a physical quantity is a quantity that you can measure. You cannot measure happiness right? So happiness is NOT a physical quantity.
There are two types of physical quantities we know, fundamental quantities and derived quantities. Fundamental quantities are there from the start, like mass, distance, time ....
Derived quantities are stuff that you get by playing around with fundamental quantities like speed, acceleration...
All these quantities have dimensions not the dimensions of 3D and 2D but dimensions of units.
How many dimensions does length have? One the dimension of length.
OK how many dimensions does velocity have( velocity=length/time)?
Acceleration? Force?(acceleration=velocity/time, force =mass* acceleration )
Try to find out objects with higher dimensions.

Chemical equations contd.

Last time we saw how to make compounds using elements and their valence. Here are some exercises for you to try

Mg +O(2)=?
Na+Cl(2)=?
HCl+ Zn=?
Post answers in the comments.

Chemical Equations.

Today we are going to talk about chemical equations.  Chemical equations are nothing more than representations of chemical reactions (we talked about them earlier) . Lets see what happens when I let an iron nail out in the rain for some time(you think).
That is an example of a chemical change. We need some method yo show what happens that is done by chemical equations.(numbers in brackets are to be put downstairs ok)

Iron+Oxygen=Iron oxide

Fe+O(2)= Fe(2)O(3)
This type of equation is called a skeletel equation I.e
The numbers of atoms on both sides are not equal.
BUT, how do I get this monster?

Fe+O(2)= Fe(2)O(3)
Well before getting into this matter you need to recall about valence.
To combine two elements to make a compound follow this "cross multiplication" process.
First write the two elements ( symbols and valence) on both sides like that:

            (3)               (2)
            Fe.               O
Then exchange the valences.
More about this in the next class.

Chemical reaction.

Last time you must recall we talked about types of changes. Well during a chemical change there is a new substance created. So in other words a chemical reaction IS a chemical change. Well there are different types of chemical reactions. Some important ones are as follows:
1) synthesis reaction
2) decomposition reaction
3) single replacement reactions
4) double replacement reactions
4) ionic reaction etc.
P.S Don't worry we will go through this hell together in the following lectures.
Memorise these for me will ya?

Types of changes!

So basically in chemistry there are two types of changes; Physical and chemical. So what do these terms actually mean?

Well a physical change we are all familiar with. What happens when you heat water? You get vapour right! Again what happens when you put a cup of water in the fridge? You get ice. Thus is an example of a physical change. You can get water back by hearing ice and cooling the vapour.
So no new thing is made right its just plain water in different forms. These forms are called states of matter. There are three states of matter, solid, liquid and gas. The ice is the solid state, water is liquid state and vapour is gas.
Ok from this we can conclude that new substances are not formed in physical changes. And that is what a physical change is.
The type of change where no new substances are formed is called a physical change.

So what is a chemical change?
A chemical change is like when you cook stuff. Suppose you are cooking vegetables. You cannot get back the original vegetable after cooking. It has transformed into something new and this is a chemical change. The type of changes where new substances are formed is called a chemical change.
Look up your book for differences on physical and chemical changes.

Valency.

Ok to understand about valences  you must know about compounds. So a compound is made up of two or more elements when they fuse together. How they fuse depends on their valency. So what the hell is this valency?
Well valency is the measure of the friendliness of add of different atoms. It is the combining capacity of atoms ok?
Are you with me?
If yes then ok else reread.
The valency of atoms is determined by how many electrons there  in the last shell of atoms which we talked about earlier.
OK here i give the valencys of the elements till 20
Also atoms like to be in octet state (don't get worried by this it just means they like to have 8 or 2 electrons in their last(remaining) shell so atoms which already have 8 or 2 don't combine.
P.S some elements have more than one valency depending on what they are combining with.
1)  Hydrogen 1
2) Helium 0
3) Lithium 1
4) Beryllium 2
5) Boron 3
6) Carbon 4
7) Nitrogen 3,5
8)Oxygen 2
9) Fluorine 1
10)Neon 0
11) Sodium 1
12) Magnesium 2
13) Aluminium 3
14) Silicon 4
15) Phosphorous 3
16) Sulphur 2,4,6(see a pattern yet?)
17)Chlorine 1
18) Argon 0
19) Potassium 1
20) Calcium 2
So look for a pattern ok? There is one! Comment if you find it.
P.S memorise this!
Next class: types of changes.