chem class(22apr)

H He

Little Belly Boy Come Near Oreo For Nutrition

Naughty Man And Silly People Should Consume A lot of

Kentucky Combo

GROUP 1 ELEMENTS:

Group 1 elements are alkaline,

Call them as Alkali metals.

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

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

Element Radius M.p B.p HardnessDensity Electro-

positivity

Li

Na

K

Rb

Cs

Fr

decrease increase

Chemical propertiesR

eact

ivit

y in

crea

se

Down the group

xx

x

x

x

3 P

3 e

3 P

2 e

3 +

2 -

1 +

Duplet (stable)

Li - 1e → Li+

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 +

K - 1e → K+

Electropositivity

Increase(↑) down the group.

The tendency to donate electrons to form positive ions

x

xx

xxx

x

xxxx

x

x

Li Na

x

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

3 reactions in group 1

With Oxygen

With water

With halogens

Reaction with oxygen

Reaction with oxygenAlkali metals + oxygen alkali metal oxides

Ex:

4 Li(s) + O2(g) 2Li2O(s)

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

Reaction with water

Reaction with waterAlkali metals + water alkaline metals hydroxide + hydrogen gas

Ex:

2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g)

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

Reaction with Halogen

Chlorine gas

Reaction with Halogen

Alkali metals + halide alkali metals halide

Ex:

2K(s) + Cl2(g) 2KCl(s)

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

Safety Precautions Alkali metals are highly reactive to water and air.

Kept under non-reactive oil (eg. Paraffin oil)

Never handle with your fingers.

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