(b) How many electrons are there in the valence shell of (i) a magnesium atom, and (ii) a chlorine atom.

(c) Show the formation of magnesium chloride from magnesium and chlorine by the transfer of electrons.

Solution:

(a) (i) Magnesium: 2, 8, 2. The first two electrons in Magnesium’s electron configuration will be in the 1s orbital. Because the 1s orbital can only carry two electrons, the following two electrons for magnesium are transferred to the 2s orbital. The six electrons in the nexus will be in the 2p orbital. Up to six electrons can be held in the p orbital. Six electrons will be placed in the 2p orbital, while the remaining two will be placed in the 3s orbital. As a result, the electron configuration of Magnesium will be 1s²2s²2p⁶3s².

(ii) Chlorine: 2, 8, 7. The first two electrons in Chlorine’s electron configuration will be in the 1s orbital. Because the 1s orbital can only hold two electrons, Chlorine’s next two electrons are placed in the 2s orbital. The six electrons after that will be in the 2p orbital. Up to six electrons can be held in the p orbital. Six electrons will be placed in the 2p orbital, followed by two electrons in the 3s orbital. We’ll shift to the 3p to place the remaining five electrons because the 3s is now full. As a result, the electron configuration of chlorine will be 1s²2s²2p⁶3s²3p⁵.

(b) (i) Magnesium atom: 2 (ii) Chlorine atom: 7

(c)