Periodicity

Periodic Trends

Reactivity

Periodicity

Periodic Trends

Reactivity^[1]

Goal 1.2.2.f: I can explain how the force of attraction of the nucleus for its electrons affects the reactivity.

Reactivity is the ability of matter to combine chemically with other substances. Some kinds of matter are extremely reactive; others are extremely unreactive. For example, the metal sodium is very reactive, even with water. When a pea-sized piece of sodium is added to a small amount of water, it reacts explosively. You can observe this reaction in the video using the below. ( Caution: Don’t try this at home!) In contrast, noble gases such as helium almost never react with any other substances.

Watch a Sodium reacts in Water video^[2]

Metals generally react by losing electrons. That means that the more weakly an electron is held by a metal, the more reactive the metal is. This is related to ionization energy. With additional energy levels, there is more shielding between the nucleus and the valence electrons. Therefore, as you increase the number of energy levels, the metal becomes more reactive.

Nonmetals generally react by gaining electrons. That means that a stronger nuclear attraction causes a more reactive nonmetal. This is related to effective nuclear charge and shielding.  The greater the nuclear charge and the lower the amount of shielding, the more reactive the nonmetal. Therefore, if you decrease the number of energy levels and use the elements in a period with the most effective nuclear charge, the nonmetal will be more reactive.

Watch an experiment that shows which of 4 metals are the most and which are the least reactive. The Reactivity Series video^[3]. In your notes, write down two things you learned and one thing you still have a question about.