How many covalent bonds does oxygen form if each of its unpaired electrons participate in one bond?

The oxygen atom has 4 valence electrons. Valence electrons are the electrons found in the outermost shell of an atom. These are the electrons that participate in chemical reactions during bonding. Since 4 electrons make up 2 pairs, an oxygen atom is capable of making 2 covalent bonds.

Heat is involved in chemical change in two ways; chemical changes either result in heat being added to or removed from an object, and chemical changes require a certain amount of heat before they can take place.

Standing in the sunlight and feeling the heat on your face (uv radiation is entering the skin, converting to infrared radiation, and is absorbed by your tissues)orstanding near a fire and feeling the heat on your skin (infrared radiation transfer)