ATOMIC STRUCTURE
Dalton and his contemporaries considered the atom as the smallest indivisible
particle of matter. However, the concept of indivisibility was proved to be
incorrect by many experiments and observed facts.
Constituents of Atom
The atom is further made of smaller particles named as subatomic or ultimate
particles. The atom has been split by physicists mainly into three subatomic
particles namely protons, neutrons and electrons (Table 1).
|
Table 1 Fundamental Units of Atom |
|
Particle |
Relative wt. |
Electric charge |
Atomic location |
Symbol |
|
Proton |
1.0073 |
1 |
nucleus |
+ or p |
|
Neutron |
1.0087 |
0 |
nucleus |
n |
|
Electron |
0.0005 |
-1 |
orbital |
- or e- |
A proton carries a positive charge. It is placed in the nucleus of an
atom and has mass nearly equal to 1 a.m.u.
A neutron is chargeless. It is placed in the nucleus of an atom and
has mass also nearly equal to 1 a.m.u.
An electron is negatively charged. It is placed in the orbital and has
negligible mass.
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