The document summarizes the properties and reactivity of alkali metals. It discusses their physical properties including softness, low density, and good heat and electricity conductivity. It describes their chemical reactivity including reactions with oxygen, halogens, nitrogen, carbon, and water. Alkali metals readily lose their outer shell electron to form +1 ions. Their reactivity increases down the group as atomic size increases. Common compounds include oxides, hydroxides, peroxides, and superoxides. Sodium and potassium are the most abundant in nature while lithium, rubidium, and cesium are rarer.

1. Chapter VII
Group IA
1

2. Alkali Metals
Compound and Uses
Physical properties
Contents
Chemical properties
Electron structure, reactivity
2

3. H
Rn
Xe
Kr
Ar
Ne
Ra Ac Rf Db Sg Bh Hs Mt Ds Rg ? ? ? ? ? ? ?
Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At
Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I
Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br
Mg Al Si P S Cl
Be B C N O F
Cs
Rb
K
Na
Li
Fr
GROUP 1 – THE ALKALI METALS
Alkali metals are in group 1 of the periodic table, on the left.
1
He
Cs
Rb
K
Na
Li
Fr
Of these alkali metals, francium (Fr) is a
very rare, radioactive and unstable
element. This makes it difficult to study.
3

4. Electron structure
All alkali metals have 1 electron in their outer shell.
H: 1s1
[He]2s1
[Ne]3s1
[Ar]4s1
⚫ They can easily obtain a full outer shell by losing 1 electron.
⚫ They lose their outer shell electron in reactions to form positive
ions with a +1 charge.
⚫ They have similar physical and chemical properties.
4

5. The reactivity of alkali metals increases from top to down the group.
What is the reason for this?
Cs
Rb
K
Na
Li
increase
in
reactivity
⚫ The size of each element’s atoms, and the number of electron
shells, increases from top to down the group.
⚫ This means that, down the group, the electron
in the outer shell gets further away from the nucleus and is
shielded by more electron shells.
⚫ This means that reactivity increases as the size of the atom
increases.
5

6. Physical properties
• Soft metals - can be cut with a knife -
softness increases from top to down the group
• Low densities - lithium, sodium and
potassium float on water
• Low melting and boiling points.
• Good conductors of heat and electricity;
6

7. Trends in density
The alkali metals generally become more dense down
the group, but the trend is not perfect because potassium
is less dense than sodium.
Water has a density of 1 g/dm3. Lithium,
sodium and potassium are less dense than water
and so will float.
Element Density (g/dm3)
lithium
potassium
sodium
rubidium
caesium
0.53
0.97
0.86
1.53
1.87
7

8. Trends in melting point
The melting point of alkali metals decreases down the
group.
Melting points are lower than for transition metals,
because alkali metals only have 1 electron in their
outer shell. Not much energy is needed for this electron
to be lost.
Element Melting point (°C)
lithium
potassium
sodium
rubidium
caesium
181
98
64
39
28
8

9. Alkali Metals
Electron structure, reactivity
Compound and Uses
Physical properties
Contents
Chemical properties
9

10. Chemical properties
- All metals are active, which show strong reduction character, and
reduction character increases from Li to Cs
- Reactions with O2:
+ At normal conditions and in the air, all metals will be oxidized.
+ Li is slowly oxidized to form a grey layer including Li2O và
Li3N.
+ Na is rapidly oxidized to form Na2O2 (with small amount
Na2O).
+ With K, the reaction is more rapidly occured to form a layer of
KO2 and some K2O.
+ Rb và Cs are easily themself burned in the air and form RbO2,
CsO2.

11. - At high temperature, air or at O2 present: Li
can be oxidized to form Li2O and some Li2O2,
but for other metals, their oxides continually
react with O2 to produce peroxide or
superoxide
Li + 0.5O2 = Li2O
Na+ 0.5O2 = Na2O
Na2O + 0.5O2 = Na2O2
K(Rb,Cs) + O2= K(Rb, Cs)O2
- These reactions indicate that the stability of
M2O2 and MO2 compounds increases gradually
as the radius of M+ increases

12. - Reaction with halogens:
With Cl2, all metals strongly react in the air and normal
temperature.
With Br2, Li and Na, reactions just occur on the surface
With K, Rb, Cs, reactions are explosive.
With I2, reaction can occur with heating.
- Reactions with N2 and C: Li directly react with N2 and C to
form Li3N and Li2C.
- Reactions with H2: Heating and form Hydrua compounds.
- Reactions with H2O: strongly react with H2O to release H2:
2M + 2HOH = MOH + H2

13. These metals are very active metals, so they do not
present as free metals, but present at compounds in
nature.
+ Na and K are popular metals on earth:
the compounds contain Na and K are sea water,
rock salt xinvinit NaCl.KCl, carnallite
KCl.MgCl2.6H2O, Na2CO3, KNO3, NaNO3.
+ Li, Rb, Cs are rare metals, they present at
alumosilicate M2[Al2Si4O12].H2O: Li+, Rb+, Cs+

14. Preparation:
Molted electrolysis of chloride salts
+ Li is prepared by electrolysis of mixture
containing LiCl and KCl at 450oC
+ Rb and Cs are prepared by the following
reaction:
at high t (700oC) and low pressure:
2RbCl + Ca = CaCl2 + 2Rb

15. Compounds
* Oxide M2O:
Li2O is prepared by direct reaction between
elements, but another M2O just prepared by mediate
reaction:
2Li + 0,5O2 = Li2O
Na2O2 + 2Na = 2Na2O
KO2 + 3K = 2K2O
- Li2O slowly reacts with H2O, but another M2O
strongly react with H2O and releases thermal energy
M2O + HOH = 2MOH

16. * Hydroxides M(OH):
- White solids, melt at relatively low temperature to
form the clear liquids.
- Adsorbs at wet air, adsorb CO2 to form cacbonate
and dissolve in alcohol and water.
- All hydroxides are strong base, react with acids and
acidic oxides to form salts
- Reacts with some amphoteric metals such as Al, Zn,
Sn and some nonmetals such as Si, halogen.

17. - Among hydroxides, NaOH is widely used in
many industries, such as paper, textile, etc.
- NaOH is prepared by electrolysis of NaCl or by
the exchange reaction:
Na2CO3 + Ca(OH)2 = CaCO3 + 2NaOH

18. * Peroxides and superoxides:
- Except for Li, all metals can form peroxides and
superoxides.
- Peroxides and superoxides are thermally stable and
do not decompose at high temperatures.
- All peroxides and superoxides strongly adsorb and
decompose in the air. They react violently with H2O
Na2O2 + 2HOH = H2O2 + 2NaOH
2H2O2 = 2H2O + O2
(In lab, this reaction is used to prepare O2)

19. - React with CO2 to release O2:
2Na2O2 + 2CO2 = 2Na2CO3 + O2
2KO2 + 2CO2 = 2K2CO3 + 3O2
- Among peroxides and superoxides, Na2O2 is most
used in reality and industry.
- Na2O2 is prepared by calcination of Na in pure air
(without CO2 and Wet water):
2Na + O2 = Na2O2
Na2O2 + O2 = 2NaO2
- Na2O2 is very strong oxidizing agent, many organic
compounds can burn when expose with Na2O2. Na2O2
is used as detergent in cleansing and washing.