1. Bonding
The periodic table shows a list of the known elements. Most of the elements are not found on their own. In fact most elements are found in compounds.
In this section we aim to understand why bonding takes place.
We will learn:
Molecule (+3 examples). Chemical bond
Noble gases stability and octet rule.
Covalent bond. + 2 examples with circle diagrams.
Single and double bonds (+ example with diagram)
Ions, ionic bonding (2 examples with diagrams)
Properties of Ionic compounds(5)
Properties of covalent compounds(5)
Exp. Show ability of covalent/ionic substances to conduct electricity.

2. Revision Needed Atomic structure What are the sub-atomic particles?
How are the electrons arranged in an atom? (circle diagrams.
Periodic table
What are group numbers?

3. Molecules Elements join together to form molecules.
Two or more atoms joined together form a molecule.
If all the atoms are the same the molecule is a molecule of an element. E.g. Chlorine.
The chlorine molecule is made of two chlorine atoms joined together.
Molecules of compounds have two or more different atoms joined together. e.g.

4. Molecules
A compound molecule – methane made of four hydrogens joined to one carbon.
Below the structure of matter

5. Bonding
Octet rule: when bonding atoms want to attain eight electrons in their outer shell.
Eight electrons in the outer shell is very stable and the noble gases of group 0 are very unreactive because of this.
Atoms form bonds in chemical reactions in order to get 8 electrons in their outer shell.

6. Bonding Ionic bonds occur between metals and nonmetals
Their are two types of bonding ionic bonding and covalent bonding.
Ionic Bonding
Ionic bonds involve the complete transfer of one or more electrons from one atom to another.
Ionic bonds occur between metals and nonmetals
covalent bonding
Sometimes atoms will share electrons. This is called covalent bonding
Covalent bonds occur between two nonmetals.

7. Ionic bonding
Sometimes when atoms react with one another, electrons are given away or accepted and the atom then becomes electrically charged. That atom is then called an ion.
Positive and negative ions attract each other and will form an ionic bond.
Example: Salt
Sodium loses an electron to chlorine and ionicaly bond to form the compound sodium chloride ( Salt.)
Ionic bonds occur between metals and nonmetals

8. An ion is a charged atom. A positive ion is an atom which has lost electrons and a negative ion is an atom which has gained electrons

9. Formation of an Ionic Bond
Na – loses an electron and now has eight in its outer shell.
It becomes Na a positive ion.
Cl – gains an electron to get 8 in its outer shell.
It becomes Cl a negative ion
Unlike charges attract.
This is an ionic bond

10. Formation of an Ionic Bond

11. Formation of a Covalent Bond
Cl – shares an electron with another chlorine.
There outer shells overlap
This is a covalent bond

12. Examples of Covalent Bonds 4 on your course (HONOURS)
Hydrogen
Hydrogen is except to the octet rule needing only 2 electrons to get a full outer shell like helium (noble gas)
The outer shell overlaps and the each hydrogen electron is shared by the other hydrogen

13. Examples of Covalent Bonds 4 on your course (HONOURS)
Methane CH4
(natural gas)
Carbon need 4 electrons to get 8 (octet rule) in its outer shell like a noble gas.
The outer shell overlaps and the 4 hydrogen atoms an electron is shared by the carbon with each hydrogen

14. Examples of Covalent Bonds 4 on your course (HONOURS)
Water H2O
Oxygen needs 2 electrons to get 8 (octet rule) in its outer shell like a noble gas. It already has 6 electrons (group VI)
The outer shell overlaps and the 2 hydrogen atoms an electron is shared by the oxygen with each hydrogen

15. Examples of Covalent Bonds 4 on your course (HONOURS)
Oxygen O2
Oxygen needs 2 electrons to get 8 (octet rule) in its outer shell like a noble gas. It already has 6 electrons (group VI)
The outer shells overlap each oxygen sharing 2 electrons with the other oxygen. When two pairs of electrons are shared it is called a double covalent bond

16. Properties of Ionic and covelant compounds

17. Showing if Ionic or covelant compounds conduct electricity
What apparatus is needed to show if a substance conducts electricity as liquid or in solution?
How do you know if the substance conducts electricity?
Which of the following do you think conduct electricity?
Sodium Chloride (NaCl)
Alcohol. (C2H5OH)
Sugar solution. (C6H12O6)
Magnesium Chloride. (MgCl2)

18. Showing if Ionic or covelant compounds conduct electricity
The compound is dissolved in solution if it is a solid.
The electrodes are dipped into the solution or liquid.
If the bulb lights the compound conducts electricity.
It is found that the bulb lights for ionic compounds only.