Chemistry C4 - Alkali Metals (Group 1)
● Group 1 metals are known as the ‘Alkali Metals’
● They all have one outer electron
● They have the same physical properties:
-low melting points and boiling points (as you go down group 1, the bp,mp
decreases)*
-low density (as you go down group 1, the density increases)
-very soft
● Group 1 metals form ionic compounds where they lose their one outer electron to
have a full outer shell:
-they lose their outer electron to form a 1+ ion
● Group 1 metals are very reactive.
● As you go down group 1, the metals are more reactive:
-the outer electron is more easily lost as it’s further from the nucleus(less
inter-molecular force)
-as a result, less energy is needed to remove the outer electron.
● Group 1 metals are called ‘Alkali Metals’ because they form alkali(hydroxide) as
one of the product when they react with water
● Group 1 metals react with water and the products are hydroxide(of a metal)
and hydrogen gas.
-For example:
2Na + 2H2O -> 2NaOH + H2
sodium + water -> sodium hydroxide + hydrogen
● The Alkali metals also react with dilute acids, btu with an acid the products
are a salt and hydrogen gas:
-For example:
2Na + 2HCL -> 2NaCl + H2
sodium + hydrochloric acid -> sodium chloride + hydrogen
*due to a decrease in the forces of attraction between the atoms
C4 Predicting and Identifying Reactions and Products - Notes 1
, Chemistry C4 - Halogens (Group 7)
● Group 7 elements are known as the ‘Halogens’
● They all have 7 outer electron
● They exist as diatomic molecules (eg. Cl2, Br2)
● As you go down group 7, the bp,mp increases (more surface area so ↑
intermolecular force)
● As you go down group 7, the density increases (larger mass)
● As you go down group 7, the metals are less reactive:
-it gets harder to attract the extra electron to fill the outer shell when it’s further
away from the nucleus
● Halogen react with alkali metals to form salts.
-For example:
2Na + Cl2 -> 2NaCl
sodium + Chlorine -> sodium chloride
● A displacement reaction is where a more reactive element replace(displace) a
less reactive element from a compound.
● A more reactive halogen can displace a less reactive one(displacement reaction):
-For example:
Chlorine is more reactive than bromine so chlorine will displace bromine:
Cl2 + 2KBr -> Br2 + 2KCl
Chlorine +potassium bromide -> bromine + potassium chloride
The solution will turn from colourless to orange as bromine is orange.
However bromine cannot displace chlorine.
*Chlorine is colourless
*Bromine is orange
*Iodine is brown
C4 Predicting and Identifying Reactions and Products - Notes 2
● Group 1 metals are known as the ‘Alkali Metals’
● They all have one outer electron
● They have the same physical properties:
-low melting points and boiling points (as you go down group 1, the bp,mp
decreases)*
-low density (as you go down group 1, the density increases)
-very soft
● Group 1 metals form ionic compounds where they lose their one outer electron to
have a full outer shell:
-they lose their outer electron to form a 1+ ion
● Group 1 metals are very reactive.
● As you go down group 1, the metals are more reactive:
-the outer electron is more easily lost as it’s further from the nucleus(less
inter-molecular force)
-as a result, less energy is needed to remove the outer electron.
● Group 1 metals are called ‘Alkali Metals’ because they form alkali(hydroxide) as
one of the product when they react with water
● Group 1 metals react with water and the products are hydroxide(of a metal)
and hydrogen gas.
-For example:
2Na + 2H2O -> 2NaOH + H2
sodium + water -> sodium hydroxide + hydrogen
● The Alkali metals also react with dilute acids, btu with an acid the products
are a salt and hydrogen gas:
-For example:
2Na + 2HCL -> 2NaCl + H2
sodium + hydrochloric acid -> sodium chloride + hydrogen
*due to a decrease in the forces of attraction between the atoms
C4 Predicting and Identifying Reactions and Products - Notes 1
, Chemistry C4 - Halogens (Group 7)
● Group 7 elements are known as the ‘Halogens’
● They all have 7 outer electron
● They exist as diatomic molecules (eg. Cl2, Br2)
● As you go down group 7, the bp,mp increases (more surface area so ↑
intermolecular force)
● As you go down group 7, the density increases (larger mass)
● As you go down group 7, the metals are less reactive:
-it gets harder to attract the extra electron to fill the outer shell when it’s further
away from the nucleus
● Halogen react with alkali metals to form salts.
-For example:
2Na + Cl2 -> 2NaCl
sodium + Chlorine -> sodium chloride
● A displacement reaction is where a more reactive element replace(displace) a
less reactive element from a compound.
● A more reactive halogen can displace a less reactive one(displacement reaction):
-For example:
Chlorine is more reactive than bromine so chlorine will displace bromine:
Cl2 + 2KBr -> Br2 + 2KCl
Chlorine +potassium bromide -> bromine + potassium chloride
The solution will turn from colourless to orange as bromine is orange.
However bromine cannot displace chlorine.
*Chlorine is colourless
*Bromine is orange
*Iodine is brown
C4 Predicting and Identifying Reactions and Products - Notes 2
