Knowing the valency (combining capacity) of common ions is essential for writing correct chemical formulas in Class 9 and 10 Chemistry.
Sodium (Na): +1
Calcium (Ca): +2
Ammonium (NH₄): +1
Nitrate (NO₃): −1
Sulphate (SO₄): −2
Monovalent (Valency = 1):
Divalent (Valency = 2):
Trivalent (Valency = 3):
Example: Write the formula of Calcium Nitrate.
The valency of sulphate (SO₄²⁻) is −2 (divalent anion).
The valency of ammonium (NH₄⁺) is +1 (monovalent cation).
How to Find the Empirical Formula of a Hydrated Salt
Learn how to calculate the empirical formula of a hydrated salt. Step-by-step guide on heating the salt, finding the mass of lost water, and calculating moles.
What is Enthalpy of Atomisation?
Learn the definition of Enthalpy of Atomisation. Understand why it is always positive (endothermic) and how it relates to bond strength and metallic bond energy.
Equilibria Involving Sparingly Soluble Salts — Ksp, Common Ion Effect Explained
Sparingly soluble salts establish ionic equilibria described by Ksp (solubility product). The common ion effect reduces solubility. Precipitation occurs when ionic product > Ksp.
What is the Formula for Equivalent Weight?
Learn how to calculate Equivalent Weight in chemistry. Discover the formulas for finding the equivalent mass of acids, bases, and salts using the n-factor.
Estimate the Change in Enthalpy and Entropy When Liquid Ammonia Vaporises
Estimate the change in enthalpy and entropy when liquid ammonia at −33.34°C vaporises. ΔH = 23.35 kJ/mol, ΔS = 97.4 J/mol·K. Step-by-step solution & formula.
Turn this guide into revision flashcards, a practice exam, or an AI-generated podcast — free, no signup required.