The Language of Chemistry
(i) Symbol of an element; valency; formulae of
radicals and formulae of compounds.
Balancing of simple chemical equations.
• Symbol – definition; symbols of the
elements used often.
• Valency - definition; hydrogen
combination and number of valence
electrons of the metals and non-metals;
mono, di, tri and tetra valent elements.
• Radicals – definition; formulae and
valencies.
• Compounds – name and formulae.
• Chemical equation – definition and
examples of chemical equations with
one reactant and two or three products,
two reactants and one product, two
reactants and two products and two
reactants and three or four products;
balancing of equations. (by hit and trial
method).
(ii) Relative Atomic Masses (atomic weights)
and Relative Molecular Masses (molecular
weights): either - standard H atom or 1/12th
of carbon 12 atom.
• Definitions
• Calculation of Relative Molecular Mass
and percentage composition of a
compound.
2. Chemical changes and reactions
(i) Types of chemical changes.
• Direct combination
• Decomposition
• Displacement;
• Double decomposition
(The above to be taught with suitable
chemical equations as examples).