Discovery of Electrons, Protons and Neutrons

Ernest Rutherford’s

In 1932, Chadwick made a fundamental discovery in the domain of nuclear science: he proved the existence of neutrons – elementary particles devoid of any electrical charge.

The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment.

A neutron is made of 3 quarks, one up quark, and 2 down quarks and many many “intermediate particles” called gluons which carry the interaction between the quarks. These gluons are exchanged very often, so the quarks feel each of other. In the nucleus you usually find protons and neutrons.

The same prevails for a proton-proton pair. Because of the repulsion between protons due both to the nucleonic force and the electrostatic force the conversion of a proton to a neutron would release energy. Such energy is required to convert a proton to a neutron because a neutron has a larger mass than a proton.

In particular, most pairs of protons in large nuclei are not far enough apart, such that electrical repulsion dominates over the strong nuclear force, and thus proton density in stable larger nuclei must be lower than in stable smaller nuclei where more pairs of protons have appreciable short-range nuclear force …

Atoms are radioactive if the protons and neutrons in the nucleus are configured in an unstable way. For large numbers of protons in the nucleus, the repulsive electric force between protons leads to stable nuclei that favor neutrons over protons. …

The three most common types of radiation are alpha particles, beta particles, and gamma rays.

Hazard pictograms (symbols)

• Explosive (Symbol: exploding bomb)
• Flammable (Symbol: flame)
• Oxidising (Symbol: flame over circle)
• Corrosive (Symbol: corrosion)
• Acute toxicity (Symbol: skull and crossbones)
• Hazardous to the environment (Symbol: environment)

1a : clover sense 1 broadly : any of several leguminous herbs (such as bird’s-foot trefoil) with leaves that have or appear to have three leaflets. b : a trifoliolate leaf. 2 : an ornament or symbol in the form of a stylized trifoliolate leaf.

The three-bladed radiation warning symbol, as we currently know it, was “doodled” out at the University of California Radiation Laboratory in Berkeley sometime in 1946 by a small group of people.

Some potassium is always taken in via the diet, and some is always excreted, meaning that there is no buildup of radioactive potassium. So, while bananas are indeed radioactive, the dose of radioactivity they deliver does not pose a risk.

Radiation damages the cells that make up the human body. Low levels of radiation are not dangerous, but medium levels can lead to sickness, headaches, vomiting and a fever. High levels can kill you by causing damage to your internal organs.

There are four major types of radiation: alpha, beta, neutrons, and electromagnetic waves such as gamma rays.

There are two kinds of radiation: non-ionizing radiation and ionizing radiation. Non-ionizing radiation has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons from atoms.

Gamma rays

To determine the type of radiation (alpha, beta or gamma), first determine the background count rate, then the source count rate with no absorber. Next, place a sheet of paper between the source and the monitor. If the counts are significantly reduced, the source emits alpha particles.