Chemical Bonding (VSAQs)

Physical Science | 8. Chemical Bonding – VSAQs:
Welcome to VSAQs in Chapter 8: Chemical Bonding. This page contains the most important VSAQs in this chapter. Aim to secure top marks in your exams by understanding these clear and straightforward Very Short Answer Questions.

VSAQ-1 : What is Lewis symbol of elements?

Definition of Lewis Symbol

  1. A Lewis symbol is a notation method representing the valence electrons of an atom or a simple ion.
  2. The valence electrons are depicted as dots (.) or crosses (x) placed around the chemical symbol of the element.

Purpose and Visualization:

Lewis symbols provide a simple and visual way to depict the arrangement of valence electrons in an atom or ion.

VSAQ-2 : Explain, why bonding angle HOH in water is 104°31 instead of 109° 28?

Bonding Angle in Water (H2O)

  1. The bond angle in H2O is 104° 31′, narrower than the ideal 109° 28′.
  2. This is due to lone pair-lone pair and lone pair-bond pair repulsions on the oxygen atom.
  3. These repulsions compress the bond angle, resulting in water’s unique bent shape.

VSAQ-3 : Draw the structure of the methane molecule. Write its bond angle.

Structure of Methane Molecule (CH4)

  1. Molecular Structure:
    • The methane molecule (CH4​) has a tetrahedral structure.
    • Carbon (C) is at the center, with four hydrogen (H) atoms symmetrically bonded to it.
  2. Bond Angle: The bond angle between hydrogen atoms in methane is 109° 28′.

VSAQ-4 : How is a sigma bond formed?

Sigma Bond Formation:

  1. A sigma (σ) bond is formed by the axial or head-on overlap of pure or hybrid orbitals from two atoms.
  2. This bond results from direct overlap of atomic orbitals along the internuclear axis between the bonding atoms.
  3. It creates a strong and stable covalent bond.

VSAQ-5 : What is the difference between lone pair and bond pair of electrons?

Difference Between Lone Pair and Bond Pair Electrons

  1. Lone Pair Electrons
    • Non-Bonding: Lone pair electrons do not participate in bond formation.
    • Existence: They are found in the outer shell of an atom, not shared with another atom.
  2. Bond Pair Electrons
    • Bond Formation: Bond pair electrons are involved in bonding between atoms.
    • Shared Electrons: These are electrons that are shared between two atoms, forming a bond.

VSAQ-6 : Define Co-ordination number.

Coordination Number:
Refers to the number of oppositely charged ions surrounding a given ion with a specific charge in a chemical compound or crystal lattice.

VSAQ-7 : NH3 has higher boiling point than PH3. Give reason.

Reason for Higher Boiling Point in NH3:
NH3 (Ammonia) has a higher boiling point than PH3 (Phosphine) primarily because NH3 can form hydrogen bonds, a strong type of intermolecular force, while PH3 cannot.