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