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Metals and Non-metals - Properties of metals and non-metals

Grade 10CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Metals are elements that lose electrons to form positive ions (cations), such as Na+Na^+, Mg2+Mg^{2+}, and Al3+Al^{3+}. They are electropositive in nature.

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Physical properties of metals: They are lustrous, malleable (can be beaten into thin sheets), ductile (can be drawn into thin wires), and are good conductors of heat and electricity. AgAg and CuCu are the best conductors.

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Non-metals are elements that gain electrons to form negative ions (anions), such as Cl−Cl^- and O2−O^{2-}. They are electronegative and generally poor conductors of electricity (except Graphite).

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Amphoteric Oxides: Metal oxides that react with both acids and bases to produce salt and water. Examples include Al2O3Al_2O_3 and ZnOZnO.

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The Reactivity Series is a list of metals arranged in the order of their decreasing activities: K>Na>Ca>Mg>Al>Zn>Fe>Pb>[H]>Cu>Hg>Ag>AuK > Na > Ca > Mg > Al > Zn > Fe > Pb > [H] > Cu > Hg > Ag > Au.

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Nature of Oxides: Generally, metal oxides are basic (e.g., Na2ONa_2O, MgOMgO), while non-metal oxides are acidic (e.g., SO2SO_2, CO2CO_2) or neutral (e.g., H2OH_2O, COCO, N2ON_2O).

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Ionic Compounds: Formed by the transfer of electrons from a metal to a non-metal. They have high melting and boiling points due to strong electrostatic forces of attraction.

📐Formulae

2Mg+O2→2MgO2Mg + O_2 \rightarrow 2MgO

4Al+3O2→2Al2O34Al + 3O_2 \rightarrow 2Al_2O_3

Al2O3+6HCl→2AlCl3+3H2OAl_2O_3 + 6HCl \rightarrow 2AlCl_3 + 3H_2O

Al2O3+2NaOH→2NaAlO2+H2OAl_2O_3 + 2NaOH \rightarrow 2NaAlO_2 + H_2O

2Na+2H2O→2NaOH+H2+Heat energy2Na + 2H_2O \rightarrow 2NaOH + H_2 + \text{Heat energy}

3Fe+4H2O(g)→Fe3O4+4H23Fe + 4H_2O(g) \rightarrow Fe_3O_4 + 4H_2

Metal+Dilute Acid→Salt+H2Metal + Dilute\,Acid \rightarrow Salt + H_2

Na→Na++e− and Cl+e−→Cl−⇒NaClNa \rightarrow Na^+ + e^- \text{ and } Cl + e^- \rightarrow Cl^- \Rightarrow NaCl

💡Examples

Problem 1:

Why does Calcium (CaCa) start floating when treated with water?

Solution:

Calcium reacts with water to form Calcium Hydroxide and Hydrogen gas. It starts floating because the bubbles of H2H_2 gas formed stick to the surface of the metal.

Explanation:

Equation: Ca+2H2O→Ca(OH)2+H2↑Ca + 2H_2O \rightarrow Ca(OH)_2 + H_2\uparrow. The buoyancy provided by the H2H_2 gas bubbles causes the metal to float.

Problem 2:

Show the formation of MgCl2MgCl_2 by the transfer of electrons.

Solution:

MgMg has atomic number 12 (2, 8, 2) and loses 2 electrons. ClCl has atomic number 17 (2, 8, 7) and needs 1 electron.

Explanation:

Mg→Mg2++2e−Mg \rightarrow Mg^{2+} + 2e^- and 2Cl+2e−→2Cl−2Cl + 2e^- \rightarrow 2Cl^-. The resulting ions attract each other to form [Mg]2+[×Cl∙]2−[Mg]^{2+} [\times Cl \bullet]^{-}_2.

Problem 3:

Why do ionic compounds have high melting points?

Solution:

Ionic compounds consist of oppositely charged ions held together by strong inter-ionic forces of attraction.

Explanation:

A considerable amount of energy is required to break these strong electrostatic bonds, resulting in high melting and boiling points.

Properties of metals and non-metals Revision - Class 10 Science CBSE