Explain the formation of sodium chloride and calcium oxide on the basis of the concept of electron transfer from one atom to another atom.

Sodium chloride

i. Sodium chloride is formed between sodium and chlorine.

ii. Sodium (₁₁Na²³) configuration is 1s²2s²2p⁶3s¹

iii. Chlorine (₁₇Cl³⁵) configuration is 1s²2s²2p⁶3s²3p⁵

iv. So, sodium tends to lose a electron i.e. 3s¹ to obtain octet in its 2^nd shell.

v. Chlorine tends to gain a electron to become 3p⁶ to obtain octet in its 3^rd shell.

vi. In this way, both sodium and chlorine become stable.

vii. So, sodium loses electron and gains positive charge and is called as sodium ion which is a cation - Na⁺¹

viii. chlorine gains electron and gains negative charge and is called as chloride ion which is a anion – Cl^-1

ix. ionic bond is formed by the transfer of electrons and the compound formed is sodium chloride.

x.

Calcium oxide

i. Calcium oxide if formed by combination of calcium and oxygen.

ii. Calcium (₂₀Ca⁴⁰) configuration is 1s²2s²2p⁶3s²3p⁶4s².

_iii. Oxygen (₈O¹⁶) configuration is 1s²2s²2p⁴_.

iv. Outer shell of calcium (4^th) contains 2 electrons. So it tends to lose these

2 electrons to obtain octet in its 3^rd shell which then becomes its outermost shell. Oxygen tends to gain 2 electrons to obtain octet in its outermost 2^nd shell.

v. In this way, both calcium and oxygen become stable.

vi. So, calcium loses 2 electrons and gains positive charge and is called as calcium ion which is a cation – Ca⁺²

vii. oxygen gains 2 electrons and gains negative charge and is called as oxide ion which is an anion – O^-2

viii. ionic bond is formed by the transfer of electrons and the compound formed is calcium oxide.

ix.