Macroscopic characteristics of dynamic equilibrium in easy learn

A few important characteristic features of dynamic equilibrium are given below:

1.An equilibrium is achievable only in a closed system (in which substances can neither leave nor enter).

2.At equilibrium state a reaction does not stop.Forward and reverse reactions keep on taking place at the same rate but in opposite direction.

3.At equilibrium state, the amount (concentration) of reactants and products do not change. Even physical properties like color, density, etc. remain the same.

4.An equilibrium state is attainable from either way, i.e. starting from reactants or from products.

5.An equilibrium state can be disturbed and again achieved under the given conditions of concentration, pressure and temperature.

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Rutherford's atomic model in easy learn

Rutherford performed 'Gold Foil' experiment to understand how negative and positive charges could coexist in an atom.He bombarded alpha particles on a 0.00004 cm thick gold foil.Alpha particles are emitted by radioactive elements like radium and polonium.These are actually helium nuclei (He2+).They can penetrate through matter to some extent.
    He observed the effects of a-particles on a photographic plate or a screen coated with zinc sulphide as shown.He proved that the 'plum-pudding' model of the atom was not correct.

                                          

*Observation made by Rutherford as following

1.Almost all  the particles passed through the foil un-deflected.

2.Out of 20000 particles, only a few were deflected at fairly large angles and very few bounced back on hitting the gold foil.

*Results of the experiment

Rutherford proposed model for an atom and concluded following results:

1.Since most of the particles passed through the foil un-deflected. therefore most of the volume occupied by an atom is empty.

2.The deflection of a few particles proved that there is a 'center of positive charges' in an atom, which is called 'nucleus' of an atom.

3.The complete re bounce of a few particles show that the nucleus is very dense and hard.

4.Since a few particles were deflected it shows that the size of the nucleus is very small as compared to the total volume of an atom.

5.The electron revolve around the nucleus.

6.An atom as a whole is neutral, therefore the number of electrons in an atom is equal to the number of protons.

7.Except electrons, all other fundamental particles that lie within the nucleus, are known as nucleons.

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