Concept preview

What you will be able to do

1. 01Add correct state symbols to an equation
2. 02Recall the seven diatomic elements
3. 03Translate a word equation into a balanced symbolic equation

Besides showing the number and type of molecules, an equation can show the phase of each species using state symbols placed in parentheses after each formula: (s) for solid, (l) for liquid, (g) for gas and (aq) for aqueous (dissolved in water). So $\mathrm{2Hg(l) + O_2(g) \rightarrow 2HgO(s)}$ tells you liquid mercury and gaseous oxygen make a solid, and $\mathrm{AgNO_3(aq) + NaCl(aq) \rightarrow NaNO_3(aq) + AgCl(s)}$ shows dissolved reactants making a dissolved product plus a solid.