Matter

1. According to particles theory of matter, all the matter is made up of tinny and discrete particles which are constantly moving randomly.
2. Particles of matter are atoms, molecules or ions.
3. Diffusion is an indirect method to show that ,Matter is made up of moving, tiny and discrete particles
4. The particles in three states of matter differ in their arrangement, energy content, movement and forces of attraction between them
5. Changes of physical state occur if substance is heated or cooled. Transfer of heat energy causes changes in the physical states of matter.

Atomic Structure

1. Each atom is made up of smaller subatomic particles, which are proton, neutrons and electrons
2. The number of protons in an atom is called its proton number
3. The total number of proton and neutron in the nucleus of an atoms is called its nucleon number
4. Number of neutron = nucleon number -  proton number
5. The element with the proton number and nucleon number can be presented in symbol form.

                                                                 A

                X

                                                                Z

A = nucleon number

Z = proton number

X= symbol of element

6. The number of proton is the same as the number of electrons in an atom because atoms are electrically neutral.

Isotopes and Their Importance

1. Isotopes are atoms of the same element but are different in the number of neutrons

The electronic structure of Atoms

1. The way electrons are arranged in an atom is called electron arrangement
2. The electrons in the outermost shell of an atom are called its valence electron
3. Atoms with same number of valence electrons exhibit similar chemical properties because chemical reaction usually involves only the valence electrons

Exercise

1.  
1. Describe the arrangement , movement , forces of attraction, kinetic energy and compressibility of particles in solid, liquid and gas
2. Describe an experiment to show that the movement of the particles of gas is faster than that of liquid.
2. You are given two white compound, namely naphtnol (melting point,65^oC) and naphthalene (melting point ,80^oC). Describe an experiment how you can differentiate each of these substance using physical method. Your answer should include:
1. Aim of experiment
2. Hypothesis
3. List of apparatus and chemicals
4. Procedure
5. Tabulation
6. Discussion
3.  
1. Your are required to determine the freezing point of naphthalene

                                                              i.      Draw labeled diagram of the apparatus used

                                                             ii.      Construct a table to record the result obtained

                                                           iii.      Sketch a graph obtained from the result of the experiment and explain your graph obtained.

2. An atom X has chemical symbol

23

        X

11

                                                              i.      What does the number 11 and 23 represent?

                                                             ii.      Write the electronic configuration of X

                                                           iii.      Draw the atomic structure of X