Question

I want some important points and summary of 1A group

Its urgentt............

Answer 1

Hey there !!!!

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IA group elements have a general configuration of ns²np¹.
Lithium(Li),Sodium(Na),Potassium(K),Rubidium(Rb),Cesium(Cs),Francium(Fr)

They possess low melting point and are soft in nature.

As we go down the group from Li to Fr 

Size increases
Metallic character increases
Reducing nature increases
Basic character increases
Ionic nature increases

Ionisation Energy decreases
Electro-Negativity decreases
Acidic character decreases
Oxidising nature decreases

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Order of density:

Cs>Rb>Na>K>Li

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Electrical Conductance:

Fused solution size of ions ---> Li⁺<Na⁺<K⁺<Rb⁺<Cs⁺ 

Order of electrical conductance --->  Li⁺>Na⁺ >K⁺ >Rb⁺ >Cs⁺ 

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Solubility of 1st group compounds :

If,Hydration Energy > Lattice energy (Highly soluble)

size of ion is inversely proportional to lattice energy

LiF to CsF   ( Lattice energy decreases more than Hydration Energy So,
                               solubility increases)

Li₂SO₄ to Cs₂SO₄  ( Hydration energy decreases ,Solubility decreases)

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General Compounds of 1A group :

Hydrides :

Ionic Character :   CsH>RbH>KH>NaH>LiH

Thermal Stability:  CsH<RbH<KH<NaH<LiH

Note : When Hydrogen compounds like HCl,H₂O,H₂SO₄ are elctrolysed,
Hydrogen gas is evolved at cathode,where as 1st group hydrides are electrolysed Hydrogen gas is evolved at anode.

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Halides :

These are ionic in nature.

Ionic Character : CsF>RbF>KF>NaF>LiF

Lattice energy : LiF>NaF>KF>RbF>CsF

Oxides :

These are classified into 3 types

1)M₂O   ( Oxide)

Ratio of M and O --> 2:1

M₂O+H₂O-->2MOH

M₂O+H₂SO₄--->M₂SO₄+H₂O

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2) Peroxides (M₂O₂)

They contain (O-O) bonds

M:O =1:1

M₂O₂+H₂O-->MOH+H₂O₂

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3)Super Oxides ( MO₂)

These are used as air purifiers they absorb atomospheric CO₂ and release oxygen gas.

2KO₂+2CO₂--->2K₂CO₃+O₂

KO₂+H₂SO₄-->K₂SO₄+H₂O₂+O₂

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Hope this helped you....................

Answer 2

1. Members of the group

Except hydrogen, the other six elements of group I, i.e., lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs) and francium (Fr) are called alkali metals since their oxides and hydroxides are soluble in water and form strong alkalies.

2. General electronic configuration

The general electronic configuration of alkali metals is ns^1 where n=2-7.

3-Atomic radii

The atomic radii of alkali metals are the largest (after inert gases) in their respective periods. Both atomic and ionic radii increase down the group from Li to Cs as the number of inner filled shells and screening effect increases.

4. Enthalpy of hydration

The enthalpy of hydration decreases with increase in ionic radii,i.e.,Li+>Na+>K+>Rb+>Cs+.

5.Ionization enthalpy

The first ionization enthalpy (∆iH1) of alkali metals is quite low but the second ionization enthalpies (∆iH2) of alkali metals are very high.

6. Electropositive character

All alkali metals are strongly electropositive due to their low ionization enthalpies.

7. Melting and boiling points.

The melting and boiling points of alkali metals are quite low and decrease further down the group due to weakening of metallic bonds.

8.Densities

The densities of alkali metals are quite low.

9.Flame colouration

Due to low ionization enthalpies, all the alkali metals and their salts impart characteristic colour to the flame.

Li-Crimson red
Na-Golden yellow
K-Pink Violet
Rb-Red Violet
Cs-Sky blue

10-Photoelectric effect.

Due to low ionization enthalpies, all alkali metals except Li show photoelectric effect.

11-Nature of bonding

Due to low ionization enthalpies, alkali metals form ionic compounds.

12-Action of water.

All alkali metals react with water evolving H2 and forming corresponding metal hydroxides,

2M+2H2O----->2MOH+H2

13-Reducing character.

Due to large negative electrode potentials, alkali metals are strong reducing agents.

14-Basic Character.

Alkali metals are strong bases and their basic character increases down the group from Li to Cs.

15-Action of oxygen

The reactivity of alkali metals towards oxygen increases down the group from Li to Cs.

For eg, Li forms Li2O (lithium oxide),Na forms mainly Na2O2 (Sodium Peroxide) and Na2O (sodium oxide) while all other form superoxides, i.e., KO2, RbO2 etc.

16-Action of air and moisture.

Alkali metals get tarnished when exposed to air and moisture due to the formation of first oxides, then hydroxides and finally carbonates.

17-Action of hydrogen

The reactivity of alkali metals towards hydrogen decreases down the group from Li tk Cs. All alkali metals on heating with hydrogen form ionic hydrides of the general formula M+H-.

Stability decreases in the order:

LiH>NaH>KH>RbH>CsH

18-Stability of carbonates

The stability of carbonates towards heat increases down the group as basic character of alkali metal hydroxides increases down the group.