MgCl2gcsescience.com 15 gcsescience.com
Chemical Reactions - Equations.
In a chemical reaction atoms are not gained or lost.
The mass of
the products is
always the same as the mass of
the reactants.
During the reaction, bonds in
the reactants are broken
and new bonds are formed to make the products.
The atoms have only swapped partners and the
total number
of atoms is the same before and after the reaction.
Each atom is represented by a
symbol.
Mg means one magnesium atom.
Cl means one chlorine atom. Cl2 means
two chlorine atoms.
In the reaction
Mg
+ Cl2
MgCl2
On the left side of the arrow,
there is 1Mg and 2Cl.
On the right side of the arrow, there is 1Mg and 2Cl.
We can see that the number of atoms in the reactants
is the same as the number of atoms in the
products.
What about
K
+ Cl2
KCl
On the left side of the arrow,
there is 1K and 2Cl.
On the right side of the arrow, there is 1K and 1Cl.
The right side needs an extra
Cl
and we say that the reaction needs to be balanced.
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