Element
An element is a substance that cannot be broken down into simpler substances by chemical means.
Eg: oxygen (O2), carbon (C), sulphur (S)
Note: Elements can be found in the Periodic Table.
Do not be confused:
1) An element can exist as molecules.Eg: hydrogen (H2), nitrogen (N2)
Molecule simply means more than 1 atom.
So, you can have the same type of atoms ( O2, N2, H2 , S8 ) or different types of atoms (CO2, CH4, H2O)
Compound
When it is made up by different types of atoms joined together chemically, it becomes a compound.
In this case, CO2 and CH4 are compounds.
A compound is a substance made up by more than 1 elements joined chemically together.
Eg: Calcium carbonate (CaCO3) ~contains 3 elements namely calcium(Ca), carbon (C) and oxygen (O)
Number of atoms in CaCO3 = 1+1+ 3(1) = 5 atoms
MIXTURE
Made up by at least 2 substances not joined together chemically.
Mixture can be catagorised by three types:
1) Element + Element
Eg: Iron(Fe) + Carbon(C)
2) Element + Compound
Eg: Copper (Cu)+ Water (H2O)
3) Compound + Compound
Eg: sodium chloride (NaCl) + water (H2O)
Common mistake made by students:
'A mixture can ONLY be separated by physical means'. (WRONG!!)
* EXPLANATION *
A mixture can also be separated by chemical means!!Compound is a substance that cannot be separated by physical means.
