Question

Define mono-valent, divalent and trivalent elements with example?

Answer 1

Valency:

• The combining capacity of an atom to complete its octet is known as its valency.
• The number of bonds that an atom can form as part of a compound is expressed by the valency of the element.
• A valency is always a whole number.
• For example, in the formation of sodium chloride (NaCl), the sodium (Na) atom donates one electron that is accepted by the chlorine atom (Cl) atom.
• Therefore the valency of sodium is 1 and that of chlorine is also 1.

Monovalent:

• An atom, with a valency of one, which thus can form one covalent bond is called monovalent.
• For example, hydrogen (H), Lithium (Li), Sodium (Na), etc. have a valency of one.

Divalent:

• An atom, with a valency of two, which thus can form two covalent bonds is called divalent.
• For example, oxygen (O), magnesium (Mg), etc. have a valency of two.
  

Trivalent:

• An atom, with a valency of three, which thus can form three covalent bonds is called a trivalent.
• For example, nitrogen (N), aluminum (Al), etc. have a valency of three.