Compounds consist of atoms of different elements. In compound the atoms are present in fixed proportion. By changing the proportion compound will changed. For example,
Nitrogen and oxygen reacted to form the compound. By changing the proportion both will form different compound.
NO₂
Nitrogen dioxide consist of one atom of nitrogen and two atoms of oxygen. Their ration is 1 :2
NO
In nitric oxide one atom of oxygen and one atom of nitrogen are present.
Their ratio is 1 : 1.
N₂O
Nitrous oxide consist of two nitrogen atoms and one oxygen. Their ratio is
2 : 1
N₂O₄
Dinitrogen tetroxide consist of two nitrogen atoms and four oxygen atoms. Their ratio will written as 2 : 4
N₂O₅
Dinitrogen pentoxide consist of two nitrogen atoms and five oxygen atoms. Their ratio will written as 2 : 5