CBSE Class 9 Answered

Electrovalency

• When one atom transfers one or more electrons to another atom, the bond formed between them is known as an electrovalent bond or electrovalency.
• The compounds thus formed, are known as electrovalent compounds.

Formation of Electrovalent Bond

• When one atom loses electrons, it acquires a positive charge. Conversely, when an atom accepts electrons, it acquires a negative charge.
• An atom possessing an electrical charge is known as an ion.
• A positively charged ion is known as a cation while a negatively charged ion is known as an anion.
• Being oppositely charged, the cation and anion are attracted towards each other and form a bond held together by the electrostatic attraction.

Let us consider the example of formation of the compound sodium chloride to understand this better.

Formation of sodium chloride molecule

• When a sodium atom and a chlorine atom combine, the sodium atom loses an electron and forms a sodium ion.
• The sodium ion is a cation i.e. it carries a positive charge.
• The chlorine atom which already has 7 electrons in its outermost orbit accepts the electron lost by the sodium atom and gets converted to a chloride ion.
• The chloride ion is an anion i.e. it carries a negative charge.
• The sodium ion and chloride ion being oppositely charged are attracted towards each other. The linkage or bond formed between these ions will be the electrovalent or ionic bond.
• The compound thus formed, NaCl or sodium chloride is known as electrovalent compound.

  Answered by | 04 Apr, 2016, 12:20: PM