PERIODIC TABLE-IGCSE /GCSE NOTES

PERIODIC TABLE



The elements in the periodic table are arranged according ti the increasing atomic number.
In the peridoic table there are eight main groups and seven periods. The elements in the same groups have similar properties because they have the same number of electrons in their outer shell.
The group number of the elements is the same as the number of the outer electrons. 3/4 of the periodic table is filled with metals.
There are other elements called the semi metals whos hare both the properties of metals and non metals.They conduct like metals and are brittle like non-metals.

GROUP 1

They are called alkali metals because they react with water to form strong alkali.

The increase in number of shells and atomic size causes increase ub the reactivity down the group because bigger the atom, the less its attractive force towards the nucleus.
Group 1 metals have one electron in the outermost shell which is why they are called group 1.
They are less dense than group 2 metals because they have only one electron in the outermost shell and they're stored under oil to prevent them from reacting iwth oxygen and water vapour form at the atnoshpere as it is dangerous.


Reaction with water

Sodium is a strong alkali, when it reacts with water :

1) It floats and melts.
2) Hydrogen gas is produced.
3) It forms sodium hydroxide.

Sodium + water ---------------> Sodium hydroxide + hydrogen
Na + H2O ---------------------> NaOH + H2
Na + HOH -------------> NaOH + H2

Potassium when reacting with water :

1) It floats.
2) It catches fire and burns with a lilac flame.
3) It forms potassium hydroxide and hydrogen.

Potassium + water --------------------> Potassium hydroxide + hydrogen
K + H2O --------------------------------> KOH + H2
K + HOH -------------------------------> KOH + H2



PERIODIC TABLE - IGCSE /GCSE CHEMISTRY REVISION NOTES


Lithium forms Lithium hydroxide and hydrogen gas when reacting with water.

Li + H2O ----------------> LiOH + H2

Rubedium (Rb)

Rb + H2O -----------> Rb (OH) + H2

When rubedium reacts with water :

1) Heat is produced.
2) Explosion takes place.
3) It forms Rubedium hydroxide and hydrogen gas.

Group 2/ halaogens /IGCSE chemistry notes

group 2


* Group 2 elements are known as alkaline earth metals.

* They can form strong alkali and they occur widely on earth crust.

* They are metals.

* They have melting points and densities that are quite low for metals.

* They react with air, water or steam to form oxides and hydroxides.

* They show the same reactivity trend as group 1, increasingly reactive as you go down the group.

* They form compounds in which the metal has a +2 ion.

* They form white or colorless compounds which gives colorless solutions.

* The alkaline earth metals are reactive, but less reactive than the alkali metals.



HALOGENS

* Each of the halogens gives colored vapour.

* Halogens react with hydrogen to form hydrogen halides.

* Halogens react with metals to form metal halides such as iron chloride and sodium chloride, ordinary salt.

* Halogens are oxidizing agents and are themselves reduced.

* Any halogen can displace another that is lower down in group 7.

* We can use ionic equations to show how halogens react.

* Halogens compounds have useful properties.

* They have diatomic molecules X2 .

* They go from gases to liquid to solid as you go down the group.

* They become less reactive towards the bottom of the group.

WORK SHEET - TEST FOR GASES

1. Suggest a method to collect the following gases. Give reason

Chlorine, hydrogen. Carbondixide , ammonia

2. complete the table

Gas ----test ------Result
hydrogen
oxygen
carbondioxide
chlorine
Sulphur di oxide



3. Draw the apparatus used to measure and collect gases





1. Suggest a method to collect the following gases. Give reason

Chlorine, hydrogen. Carbondixide , ammonia