Bright Tutorials Bright Tutorials
ICSE Class 7 Chemistry Question 8 of 16

Atomic Structure — Question 13

Back to all questions
13
Question

Question 13

Give an example of three elements exhibiting variable valency.

Answer

Three elements exhibiting variable valency are:

  1. Iron (Fe) can show a valency of 2 and 3.
  2. Copper (Cu) can show a valency of 1 and 2.
  3. Lead (Pb) can show a valency of 2 and 4.

ICSE Class VII Chemistry Chapter 3 15 Marks

Atomic Structure — Quick Study Guide

Atoms are the building blocks of all matter. Understanding atomic structure is essential for all of chemistry.

Key Definitions

  • Atom: Smallest particle of an element with its chemical properties
  • Molecule: Group of two or more atoms bonded together
  • Element: Pure substance with only one type of atom
  • Compound: Two or more different elements chemically combined
  • Atomic number (Z): Number of protons = Number of electrons
  • Mass number (A): Protons + Neutrons
  • Valency: Combining capacity of an element
  • Isotopes: Same element, different mass numbers

Electronic Configuration Rules

K shell = max 2 electrons, L shell = max 8, M shell = max 8 (for first 20 elements). Fill inner shells first.

Exam Tips

  • Memorise symbols of first 20 elements
  • Practice calculating protons, neutrons, electrons from Z and A
  • Practice drawing Bohr diagrams
  • Valency: if outermost ≤ 4, valency = outermost; if > 4, valency = 8 - outermost

Bright Tutorials | ICSE Class VII Chemistry | Chapter 3: Atomic Structure | Contact: 9403781999