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Class 10, Science, Chapter-3, Lecture-1, Metals & Non-metals (Notes)

 

PHYSICAL PROPERTIES OF METALS AND NON-METALS:

1. PHYSICAL STATE:

Metals are Solids at room temperature. [Exception – MERCURY]
Non-metals can be Solid, Liquid, or Gas. [Gases – 11; Solids – 10; Liquid – 1]

  • Liquid metal – MERCURY
  • Liquid non-metal– BROMINE

2. MALLEABILITY:

Metals are malleable (can be hammered into thin sheets.) 

Non-metals are BRITTLE

  • Best malleable metal – GOLD
  • Most ductile metal – GOLD

3. DUCTILITY:

Metals are ductile (can be drawn into wires)

Non­-metals are non-ductile.

  • Best Conductor – SILVER
  • Poorest conductor – LEAD

4. THERMAL AND ELECTRICAL CONDUCTIVITY:

Metals are good conductors of heat and electricity.

Non-metals are bad conductors of heat and electricity. [exception – GRAPHITE]

5. HARDNESS:

Metals are hard [ exception – SODIUM, POTASSIUM]

Non-metals are soft [exception – DIAMOND]

6. MELTING AND BOILING POINT:

Metals have high melting point and boiling point. [ exception – SODIUM, POTASSIUM]

Non-metals have low melting point and boiling point. [ exception – DIAMOND, GRAPHITE]

CHEMICAL PROPERTIES OF METALS AND NON-METALS:

1. Electronic Configuration of Metals

Number of valence electrons = 1, 2, or 3

Electronic Configuration of Non-metals:

Number of valence electrons = 4, 5, 6, 7, or 8.  [Exception – Hydrogen and Helium]

Metals are Electropositive elements:

Reason: metal atoms lose 1, 2, or 3, electrons and form positively charged ions.

${\rm{Na}}\buildrel {{\rm{}}} \over \longrightarrow {\rm{N}}{{\rm{a}}^{+ }} + {e^ - }$ (accepts 1 electron)

${\rm{Mg}}\buildrel {{\rm{}}} \over \longrightarrow {\rm{M}}{{\rm{g}}^{2 + }} + 2{e^ - }$ (accepts 2 electrons)

Non-metals are electronegative elements.

Reason: non-metal atoms accept 1, 2, or 3 electrons and form negatively charged ions.

$P + 3{e^ - }\buildrel {} \over \longrightarrow {P^{3 - }}$ (accepts 3 electrons)

2. Reaction with Oxygen:

METALS react with oxygen to form metal oxides which are basic OR amphoteric in nature.

$${\rm{4~ Na }} + {\rm{~ }}{{\rm{O}}_2}{\rm{~ }}\buildrel {} \over \longrightarrow {\rm{ 2~ }}{{\rm{Na}}_2}{\rm{O}}$$

$${\rm{2~ Mg }} + {\rm{~ }}{{\rm{O}}_2}{\rm{~ }}\buildrel {} \over \longrightarrow {\rm{ 2~ MgO}}$$

$${\rm{2~ Ca }} + {\rm{~ }}{{\rm{O}}_2}{\rm{~ }}\buildrel {} \over \longrightarrow {\rm{ 2~ CaO}}$$

Examples of amphoteric Oxides:

  • Aluminium Oxide ( Al2O3 )
  • Zinc Oxide ( ZnO )

Some metal oxides react with water to form alkalies

Example – $${\rm{N}}{{\rm{a}}_2}{\rm{O }} + {\rm{ }}{{\rm{H}}_2}{\rm{O }}\buildrel {} \over \longrightarrow {\rm{ }}\mathop {{\rm{2~ NaOH}}}\limits_{{\rm{Sodium ~Hydroxide}}} $$

NON–METALS react with oxygen to form acidic OR neutral oxides which are covalent in nature.

$$C + {O_2} \to C{O_2}$$

$$Si + {O_2} \to Si{O_2}$$

$${P_4} + 5{O_2} \to 2{P_2}{O_5}$$

$$S + {O_2} \to S{O_2}$$

$$2S + 3{O_2} \to 2S{O_3}$$

Examples of Neutral Oxides:

  • Carbon monoxide (CO)
  • Nitrous Oxide (N2O)
  • Nitric Oxide (NO)
  • Water (H2O)

4. Reaction with Water:

Metals react with water to produce a metal hydroxide or metal oxide and hydrogen gas.

${\rm{2~ Na }}(s){\rm{~ }} + {\rm{ 2~ }}{{\rm{H}}_2}{\rm{O }}(l){\rm{ ~}}$ $\buildrel {} \over
\longrightarrow {\rm{ 2~ NaOH }}(aq){\rm{ }} + {\rm{ ~}}{{\rm{H}}_2}(g)$

${\rm{2~ K }}(s){\rm{~ }} + {\rm{ 2~ }}{{\rm{H}}_2}{\rm{O }}(l){\rm{ ~}}$ $\buildrel {} \over
\longrightarrow {\rm{ 2~ KOH }}(aq){\rm{ }} + {\rm{ ~}}{{\rm{H}}_2}(g)$