Reactivity. Reactivity of Group II elements increases down the group. This can be explained by the increase in ease at losing two outer electrons as we descend the group. The loss of electrons becomes easier due to the decreasing ionisation energy required.

The reactivity of group 1 elements increases as you go down the group because: the atoms become larger. the outer electron becomes further from the nucleus. the force of attraction between the nucleus and the outer electron decreases.

Halogens from bromide to fluorine get more reactive because the force of attraction between the nucleus (core) and the outer electron get stronger as you go up group 7 elements. The distance “a” is less than “c” and the force of attraction between the nucleus and the outer shell increases with shorter distances.

Fluorine

The non-metal elements in Group 7 – known as the halogens – get less reactive as you go down the group. This is the opposite trend to that seen in the alkali metals in Group 1 of the periodic table . Fluorine is the most reactive element of all in Group 7.

2 (b) Reactivity of Group 2 Elements. The overall trend, for the reactivity of Group 2 metals with water, is an increase down the group. The outer electrons are easier to remove as they are further from the nucleus and there is more shielding resulting in a lower nuclear attraction.

These metals are less reactive than the neighboring alkali metal. Magnesium is less active than sodium; calcium is less active than potassium; and so on. These metals become more active as we go down the column. Magnesium is more active than beryllium; calcium is more active than magnesium; and so on.

Both elements are in the same group but valence electrons of calcium are further away from the nucleus. They are not strongly held by the nucleus, hence are readily released. And readily released electrons means higher reactivity.

Group 2A (or IIA) of the periodic table are the alkaline earth metals: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). They are harder and less reactive than the alkali metals of Group 1A.

Sodium easily lose electrons than magnesium and get oxidized to easily. Sodium with atomic number of 11 has electronic configuration of 2,8 ,1. thus it has to lose one electron to attain noble gas configuration whereas Magnesium with atomic number of 12 has electronic configuration of 2,8, 2.

Silver, gold, and platinum are metals with the least reactivity. They are found in nature.

As potassium is larger than sodium, potassium’s valence electron is at a greater distance from the attractive nucleus and is so removed more easily than sodium’s valence electron. As it is removed more easily, it requires less energy, and can be said to be more reactive.

Hint: Sodium metal reacts with the oxygen of the air at room temperature radially and undergoes oxide formation. Hence, sodium is stored under kerosene to prevent its reaction with oxygen, moisture, and carbon dioxide.

The reactivity series lists metals in order of their reactivity. Copper is the only metal apart from precious metals that will not react with water or dilute acids. It will react very slowly with oxygen.