Metals and Non-metals — Part 2: Ionic compounds, extraction of metals and corrosion: visual lesson, CBSE Class 10 Science

Lesson

Ionic compounds, metallurgy and corrosion

Part 2 — how metals and non-metals bond, how metals are extracted from their ores and refined, and how we protect them from corrosion.

In this lesson you will

Show the formation of ionic compounds such as NaCl and MgCl2 with electron-dot structures
Explain the melting points, solubility and conductivity of ionic compounds
Outline concentration, roasting, calcination and reduction for metals of low, medium and high reactivity
Describe electrolytic refining of copper with a labelled diagram
Explain the conditions for rusting and how galvanising, painting and alloying prevent it

Concept

Why atoms bond: the stable octet

Noble gases have completely filled outer shells (8 electrons, or 2 for helium) and are very unreactive. Other atoms lose or gain electrons to reach such a stable arrangement, forming ions.

Table showing sodium and magnesium losing electrons and chlorine and oxygen gaining electrons to reach noble-gas configurations
Atom	Electronic configuration	Change	Ion formed
Sodium (Na)	2, 8, 1	loses 1 electron	Na⁺: 2, 8
Magnesium (Mg)	2, 8, 2	loses 2 electrons	Mg²⁺: 2, 8
Chlorine (Cl)	2, 8, 7	gains 1 electron	Cl⁻: 2, 8, 8
Oxygen (O)	2, 6	gains 2 electrons	O²⁻: 2, 8

Diagram

Forming sodium chloride

Dots are chlorine electrons; the cross is the electron that came from sodium. Only outer-shell electrons are shown.

Sodium transfers one electron to chlorine. The oppositely charged ions, $\ce{Na+}$ and $\ce{Cl-}$ , attract each other strongly: an ionic (electrovalent) bond.

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