proton

Let Us Learn About Protons

The proton was discovered by Ernest Rutherford in 1918 since the proton is in the atomic nucleus, it is a nucleon. Since it has a spin of -1/2, it is a fermion. Since it is composed of three quarks, it is a triquark baryon, a type of hadron. Since the atom is electrically neutral there had to be positively charged particles present in the atom to neutralize the negative charge of the electrons.

Production of Anode Rays

Goldstein experimentally proved the existence of positive charge in matter.

In his experiments, a perforated cathode was used in a discharge tube along with air at very low pressure of about 0.001 mm of mercury. When a high voltage of about 10,000 volts was applied to this cathode in the discharge tube, a faint red glow was observed behind the perforated cathode.

The rays were formed at the anode and when these rays struck the walls of the discharge tube behind the anode they produce a faint red light. Since the rays were formed at the positive electrode or anode, they were known as anode rays or positive rays.

Formation of Positive Rays

When high electrical voltage is applied to a gas, its ato

ms break up into negatively charged particles (electrons) and positively charged particles. These positively charged particles formed by the removal of electrons from the gas atoms are called positive rays.

Effect of Low Pressure in the Discharge Tube

When the gas atoms in the discharge tube are at atmospheric pressure they collide with the electrons preventing them from reaching the anode. As no electrons reach the anode no current flows through the discharge tube. When the gas pressure is very low there are few gas atoms in the discharge tube. As such there is no hindrance to the movement of electrons the gas conducts electricity.

Characteristics of a Proton

Mass of a proton

A proton can be thought of as a hydrogen atom that has lost its electron. Since the mass of an electron is small, the mass of a proton is equal to the mass of a hydrogen atom. As the mass of hydrogen atom is for all practical purposes 1 a.m.u., the relative mass of a proton is 1 a.m.u. The absolute mass of a proton is 1.6 x 10^-24 gram.

Compared to an electron, a proton is very dense. It is about 1837 times denser than an electron. It means that almost all the mass of the atom is in the nucleus.

Charge of a Proton

The proton has an equal and opposite to the charge of an electron. So, the absolute charge of a proton is 1.6 x 10^-19 coulomb of positive charge. This being the smallest positive charge carried by any particle, it is taken as 1 unit positive charge. The relative charge of a proton is +1 (plus one).

Effect of low pressure in the discharge tube

When the gas atoms in the discharge tube are at atmospheric pressure they collide with the electrons preventing them from reaching the anode. As no electrons reach the anode no current flows through the discharge tube. When the gas pressure is very low there are few gas atoms in the discharge tube. As such there is no hindrance to the movement of electrons and the gas conducts electricity.