What is Thomson's model of atom? What are its drawbacks?

List the conclusions drawn from Rutherford's scattering experiments.

What are the drawbacks of Rutherford's model of atom?

How was neutron discovered?

What does the atomic number of an element tell about the element?

Write down the electronic configuration of the following:

Oxygen (Atomic number $=8$).

Write down the electronic configuration of the following:

Phosphorous (Atomic number $=15$).

Write down the electronic configuration of the following

Calcium (Atomic number$=20$)