Formation of Compound

1. The noble gases are inert and monoatomic because they have stable electronic structure (octet and duplet)
2. Atoms combined together through chemical bonding to achieve stability and to acquire stable electronic structure
3. Two main way of forming chemical bonds between atoms are ionic bond and covalent bonds.
4.  

Ionic Bond: The Transfer of Electrons

1. Ionic bonds are formed when electrons are transferred from metal atom to non-metal atoms to form positive and negative ions
2. Positive ions (cation) are formed when atoms lose electron. Negative ions (anions) are formed when atom gain electrons.
3. Metal atoms usually form positive ion whereas non-metal atom form negative ions to achieve stability in their electron arrangement
4. The ionic bonds are the strong electrostatic forces of attraction between positive and negative ions.

Covalent Bond: The Sharing of Electron

1. Covalent bond are formed between atoms of non-metal by overlapping their outermost shell
2. Atoms of non-metal share electron to form stable and neutral molecules in covalent compound or elements
3. In covalent bonding, each atom in molecule contribute an equal number of electrons for sharing
4. There are three type of covalent bond, single, double and triple covalent bonds.

Properties of ionic and covalent compound

1. Ionic compound
1. Have high melting and boiling points
2. Conduct electricity when molten and in aqueous solution
3. Are often soluble in water but not in organic solvents
2. Covalent compound
1. Have low melting and boiling points
2. Do not conduct electricity
3. Are often insoluble in water but soluble in organic solvents.
3. Covalent compound which are liquid at room temperature are often used as organic solvents

EXERCISE

1. The table above shows the proton number of 3 element P, Q, and R. Explain how

                                                              i.      P and R react to form a compound

                                                             ii.      Q and R react to form a compound

                                                           iii.      State the different in two physical between the compound above

                                                          iv.      Describe an experiment to shows a different in one of the physical properties mentioned in (iii) above

2.  
1. Using sodium chloride and methane as example, explain how

                                                              i.      Ionic, and

                                                             ii.      Covalent compound are formed

2. State three physical different between ionic and covalent compound