Calcium chloride is used to make pickles. The calcium atom transfers electrons to chlorine atoms, leading to the formation of chemical bonds. Calcium chloride contains bonds. Copper atoms are used to produce pennies. The copper atoms in pennies share many electrons. Pennies contain bonds. Hydrochloric acid is the main acid that helps break down food in the stomach. The atoms of hydrochloric acid share electrons. Hydrochloric acid contains bonds.