Question

about atom structure

Answer 1

Atom is the smallest indivisible particle of the matter. Atom is made of electron, proton and neutrons.

Electron was discovered as a result of study of cathode rays by JJ Thomson. It was named by Stony

It carries a unit negative charge (-1.6 * 10-19 C).

Mass of electron is 9.11 * 10-31 kg and mass of one mole of electron is 0.55 mg.

Some of the characteristics of cathode rays are:

These travel in straight line away from cathode and produce fluorescence when strike the glass wall of discharge tube.
These cause mechanical motion in a small pin wheel placed – their path.
These produce X-rays when strike with metal and are deflected by electric and magnetic field
Proton

Rutherford discovered proton on the basis of anode ray experiment.

It carries a unit positive charge (+1.6 * 10-19) C).

The mass of proton is 1.007276 U.

The e / m ratio of proton is 9.58 * 10-4 C / g. (e / m ratio is maximum for hydrogen gas.)

Some of the characteristics of anode rays are :

These travel in straight line and posses mass many times the mass of an electron.
These are not originated from anode.
These also cause mechanical motion and are deflected by electric and magnetic field.
Specific charge (e / m) for these rays depends upon the nature of the gas taken and is maximum for H2
Neutron

Neutrons are neutral particles. It was discovered by Chadwick (1932). The mass of neutron is 1.675x 10-24 g or 1.008665 amu or u.

Answer 2

Atom is the smallest particle which doesn't exist in free state..and it take part in chemical reactionsl.

Atom is made up of 3 fundamental particles..
1)Electron
2)proton
Electron is negatively charged,proton is positively charged and neutron has no charge.i.e it is neutral.
it is due to the reason number of electron is equal to number of protons.
so atom is electrically neutral.