Q1. The ancient Greeks thought that atoms were tiny spheres that could not be divided into anything smaller. Since then, different discoveries have led to the model of the atom changing.
Some of the discoveries are given in the table below.
The mass of an atom is concentrated in the nucleus.
A
Electrons orbit the nucleus at specific distances.
B
The nucleus contains neutrons.
C
The nucleus contains positively charged protons.
D
(a)
Which discovery was the earliest?