Atomic calculation

For around 3 centuries ago, scientist of the world has agreed to use hydrongen's mass as the calculation for all the atomic mass.

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You gotta be exposed to terms like outermost shells, cation, anion, oxidation, reducing agent all this terms because I know teacher is not gonna repeat. I'll be using such terms from my next post onwards so prepare yourself. Starting will be a little difficult but once you get used to it you will find it quite easy to comprehend.
H2SO4 is sulfuric acid
HCl is hydrochloric acid
NH3 is ammonia
NH4 is ammonium
Etc and Etc.
The compounds with the name that ends with ide are anions.
During the holidays I will post relative masses of atoms and molecules. It's not an easy chapter so yeah read up before I even start anything!! Goodluck for your test I've done what I can(:

Physical properties of ionic vs covalent substances

From this point onwards I'm gonna use chemical symbols because you must be exposed to it in order to improve your chemistry.
1. Melting and Boiling point
Ionic compound- For instance, sodium chloride melts and boils at very high temperatures or we can call it extreme temperatures. This is because the bonds are relativly strong thus it is hard to break them. A super strong heat is needed to break their molecule force.
Covalent compound- For instance, Hydrogen oxide(h2o) has a low boiling and melting points. This means that the bond within the molecules are weak so they can easily be changed into gaseous state or solid states.
2. Volatility
Ionic compound- The bonds within each molecules are strong so it is difficult for the molecules to break up. That is why usually ionic compound exist in solid states, and why there's no smell from them.
Covalent compound- The bonds within each molecules are weak so little heat energy is needed to break their bonds within the molecules. That is why usually we can smell the sweet perfumes.
Volatile are substances that can be evaporated easily. Such example would be Hydrogen oxide.
non-volatile are substances that cannot be evaporated easily. Such example would be Sodium Chloride.
3. Electrical Conductivity
Ionic compound- They do not conduct electricity in solid states because the ions are not moving. They do not have enough energy to move about in solid state. Only when in liquid or dissolve in water can conduct electricity because their ions can move more freely in liquid states.
Covalent compound- They do not conduct electricity at all because they are sharing electrons not transfering electrons. Covalent compounds do not have ions so current cannot flow. If you're taking physics you can ask me. People taking biology don't have to know why.
4. Solubility
Ionic compound- Some can dissolve in water. Sodium chloride can be found in salt waters.
Covalent compound- They can be dissolve in organic solvent but not water. This is biology now wahaha. Example, there are such thing called tringlyceride that can be dissolved in human fats to provide energy.

Ionic bonding

http://www.youtube.com/watch?v=xTx_DWboEVs&feature=related

This can be a short introductory to ionic bonding. Okay the electron configuration drawing are shit so don't copy it.
Ionic bonding is the transfer of electrons from an element to another element. Ions are formed when an atom loses or gain electron(s).
A positive ion(cation) is formed when an atom loses it's outer shell electrons to have a fully filled outermost shell.
A negative ion(anion) is formed when an atom gain electrons to have a fully filled outermost shell.
Formation of ionic bonds
One example of ionic bonding can be .... sodium chlroride. A sodium atom would lose one of it's valence electrons to form anion because it has only 1 electrons in it's outermost shell. A chlorine atom would then receive the electron to have a fully filled outermost shell. In this way both of the atoms have fully filled outermost shell which means they are stable but under one condition that is they have to bond together. Initially by itself a sodium atom is Na+ and chlorine would be Cl- . Final result would be NaCl. The forces between them is very strong. This force that is between them are called electrostatic force.
if you want more examples ask me personally. I can't draw out in blogs sorry yeah.
Formation of covalent bonds
Covalent bonding means the sharing of electrons like mrs ow had said. There are single bond. Double bond. Triple bond.
Single bond is the sharing of a pair of electrons
Double bond is the sharing of 2 pairs of electrons
Triple bond is the sharing of 3 pairs of electrons
Covalent bond can only be formed in non-metals group.
For instance, a hydrogen atom has 1 outer electrons and it wants to have a fully filled outermost shell. So, it will share with another hydrogen atom to have a fully filled outermost shell. In this case they share a pair of electrons. So you roughly get the idea of double and triple bond. I couldn't draw it out sorry yeah. Ask me personally if you wanna learn more.

Type of bonding

There are three types of bonding(combine chem only need to know two)
1. Metallic bonding
2. Ionic bonding
3. Covalent bonding
Metallic bonds for combine chem don't have to know you wanna know can ask me via facebook.

Revision

Alright I know lots of you get confused with isotopes. They have different number of neutrons not protons.
The valence shell electrons can be determined by their group. For instance, carbon has 4 outer electrons in it's outermost shell so it will be in group4. Group 4 are unique elements. They can decide to whether give or take electrons.
The number of shells can be determined by their period. Carbon has 2 shells so it will be in period 2.

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One thing to clarify before I continue.. I'm not a teacher I'm a student like you so I won't get all the answers right.