4. Find the valency of atoms of chlorine, sulphur and magnesium.​

1. Chlorine = 7 valence electrons.

2. Sulphur = 6 valence electrons.

3. Magnesium = 2 valence electrons.

Explanation:

In Chemistry, valence electrons can be defined as the number of electrons present in the outermost shell of an atom. Valence electrons are used to determine whether an atom or group of elements found in a periodic table can bond with others. Thus, this property is typically used to determine the chemical properties of elements.

1. Chlorine = it is an element found in group (7) of the periodic table known as halogens and as such it has 7 electrons in its outermost shell. Therefore, Chlorine has seven (7) valence electrons.

Sulphur = this element is found in group (6) of the periodic table and as such it has 6 electrons in its outermost shell. Therefore, Sulphur has six (6) valence electrons.

Magnesium = this element is found in group (2) of the periodic table and as such it has 2 electrons in its outermost shell. Therefore, Magnesium has two (2) valence electrons.