Begin by writing formulas for the reactants and products, including physical states. When necessary use coefficients to balance the equation. Click in the answer box to open the symbol palette.

(a) When solid sodium hydride, NaH, is added to water, hydrogen gas is released and aqueous sodium hydroxide forms.

AP 1

(b) Aluminum metal reacts with chlorine gas to form solid aluminum chloride.

NaH(s) + H2O(l) > NaOH(aq) + H2(g)

2Al(s) + 3Cl2(g) > 2AlCl3(s)

Explanation:

The rule of thumb in balancing chemical reaction equation is that the number of atoms of each element on the reactant side must be the same as the number of atoms of the same element on the product side. Only then can any reaction equation be seen as balanced.

For example there are two aluminum atoms on both sides of the reaction equation and six chlorine atoms on both sides of the reaction equation. Hence the reaction equation is balanced.

"the periodic table is arranged in order of atomic number."

a polar bond is formed when electrons are shared unevenly between atoms