4th Period: Potassium and Calcium—Electrons go into the fourth energy level. A small piece of sodium metal is placed in water. The sodium reacts with the water and gets very hot, producing sodium ...

Sodium would react very quickly with water to produce hydrogen gas in an exothermic reaction (a reaction that transfers energy to the surroundings). This would happen whenever the cutlery was put ...

A small piece of sodium metal is placed in a flask of chlorine gas. A little water helps expose the sodium so it can react with the chlorine gas. The reaction releases a lot of heat as the ionic ...

The apparatus below is used to react calcium with water and collect the gas. This would not be used with sodium or potassium as they float and the reaction is too vigorous.

In a triumph for NASA’s first asteroid sample return mission, new findings suggest that tiny bits of rock retrieved from the ...

Commercial heat packs (containing iron and water, or supersaturated sodium acetate) and cold packs (various ammonium salts) can be used to show exo- and endothermicity. Heat packs that contain iron ...