Download - Chem class(22apr)
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H He
Little Belly Boy Come Near Oreo For Nutrition
Naughty Man And Silly People Should Consume A lot of
Kentucky Combo
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GROUP 1 ELEMENTS:
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Group 1 elements are alkaline,
Call them as Alkali metals.
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Physical properties of group 1 elements
soft metals
silvery and shiny surfaces
low melting and boiling points
good conductors of heat and electricity
low density
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When down the group 1….1. Hardness
2. Atomic size the number of atomic shell ↑
3. melting point and boiling point atomic size ↑ distance between the nucleus and the valance electron shell ↑ metallic bond between atoms ↓
4. Density Size ↑ mass more than increase in volume atoms are closer
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Element Radius M.p B.p HardnessDensity Electro-
positivity
Li
Na
K
Rb
Cs
Fr
decrease increase
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Chemical propertiesR
eact
ivit
y in
crea
se
Down the group
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xx
x
x
x
3 P
3 e
3 P
2 e
3 +
2 -
1 +
Duplet (stable)
Li - 1e → Li+
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x
xx
xxx
x
xxxx
xx
xxx
x
xxxx
11 P
11 e 11 P
10 e
11 +
10 -
Na - 1e → Na+
Octet (stable)
1 +
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K - 1e → K+
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Electropositivity
Increase(↑) down the group.
The tendency to donate electrons to form positive ions
x
xx
xxx
x
xxxx
x
x
Li Na
x
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Down the group 1, Reactivity ↑
Atomic size ↑
The 1 valence electron become far from the nucleus.
The force of attraction of nucleus on the valence ↓
The single electron becomes easier to be release.
Reactivity ↑
Li < Na < K < Rb < Cs < Fr
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3 reactions in group 1
With Oxygen
With water
With halogens
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Reaction with oxygen
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Reaction with oxygenAlkali metals + oxygen alkali metal oxides
Ex:
4 Li(s) + O2(g) 2Li2O(s)
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metal reaction Phenolphthalein indicator
LiBurn with a red flame.
Turns pink
NaBurn with a brightyellow flame.
Turns pink
K Burn violently with a
very bright purplish flame.
Turns pink
Reactivity
↑down the group
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Reaction with water
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Reaction with waterAlkali metals + water alkaline metals hydroxide + hydrogen gas
Ex:
2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g)
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metal
reaction Phenolphthalein indicator
Li Move slowly on the water surface. Turns pink
Na Move at a fast speed on water
surface with a “hissing” sound, burn
with yellow flame.
Turns pink
K Move very fast speed and burn
with a purple flame.
Turns pink
Reactivity
↑down the group
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Reaction with Halogen
Chlorine gas
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Reaction with Halogen
Alkali metals + halide alkali metals halide
Ex:
2K(s) + Cl2(g) 2KCl(s)
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metal reaction product
Li Burn slowly with a
reddish flame.
White solid is obtained
Na Burn brightly with a
yellowish flame.
White solid is obtained
K Burn very brightly with purplish flame.
White solid is obtained
Reactivity
↑down the group
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Safety Precautions Alkali metals are highly reactive to water and air.
Kept under non-reactive oil (eg. Paraffin oil)
Never handle with your fingers.
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Summary:
Physical
• Shiny and silvery surface
• conductors of heat and electricity
• Hardness
• Atomic size
• Mp
• Bp
• density
Chemical
• Electropositivity
• Reactivity:
• Reaction with oxygen
• Reaction with water
• Reaction with chlorine