I noticed that there has been this 适 word after every post. I'm not sure if it is necessary but best if can take it away.

To everyone including anoynomous people who insult: Let's stop talking about detentions, notes left on your table, quarrels, revenge, scoldings and anything that will increase tension here. Talk about other stuff lah.

Lastly, here's a cool picture:

Hello I'm Vincent the Science Rep and I just very bo liao so let's revise CHEMISTRY=D

First is the element. An element is a pure substance that cannot be broken down into any simpler substance. There are 109 elements in total . Anyway they are all arranged in the periodic table.


(Click for larger image. Taken from Wikipedia www.wikipedia.org)

Group=A column(vertical) in the periodic table. For example,beryllium, magnesium, calcium are all in the same group. Elements in the same group have similar properties
Period=A row(horizontal) in the periodic table. Potassium, calcium, scandium and titanium are in the same period. A period shows a gradual change from metallic properties(left) to non-metallic properties(right).

Properties of metallic elements:Good conductor of heat & electricity, ductile(can be pulled into wires), malleable(can be beaten into any shape), shiny, have high densities...
Properties of non-metallic elements: Poor conductor of heat & electricity, dull, have low densities, brittle(solids)

IMPORTANTZ: I cannot gurantee that all the metallic and non-metallic elements have all these properties.

Compounds and Mixtures

A compound is a substance made up of two or more elements chemically combined together. Here are some common compounds found in our everyday life: Water=hydrogen and oxygen, salt=sodium and chloride, sugar=carbon,hydrogen and oxygen.

A mixture is a substance made up of two or more substances chemically combined together. Got lots of mixtures which will take up a lot of time so go read your textbooks and worksheets.

Properties of Compounds and Mixtures


Well I have made a 'picture' showing all the properties of compounds and mixtures. Click on it to enlarge.


Seperation of Mixtures

Yes'd finally we are reaching the final topic. There are 5 ways to separate mixtures. They are magnetic attraction, filtration, evaporation, distillation and chromatography.

1)Magnetic Attraction
It is used to seperate magnetic substances from non-magnetic substances


2)Filtration
Filtration is used to seperate an insoluble solid from a liquid. For example, sand from water.
Diagram:


(Click to enlarge)

3)Evaporation
This is used to seperate a soluble solid from a liquid. Example=Salt solution

4)Distillation
This is used to seperate liquid from a solution. Example=Seawater


(Click to enlarge. Taken from Wikipedia www.wikipedia.org)

5)Chromatography

This is used to seperate dyes from inks/colours

If you spot a mistake, please tell me=D=D=D