7. Atoms

The atom is the basic unit of matter which is the smallest thing that can have a chemical property. Atoms are made up of two types of hadron particles; the protons (positively charged particles), the neutrons (particles with no charge) and one type of lepton particles called the electrons (negatively charged particles).

The protons and the neutrons are heavier and remain stay at the middle of the atom as a nucleus of the atom. But usually in nature, like charges or same charged particles repel each other, then how the positively charged protons in the nucleus remain stayed together? This was solved by finding a particle called Gluon. Like as glue, gluons act like atomic glue by sticking the protons together using the strong nuclear force. It is this force which also holds the quarks together that make up the protons and neutrons. The nucleus is surrounded by a cloud of electrons which are very lightweight. The electrons have the negative charge and the nucleus have the positive charge, so they attract each other and the electrons orbit or travel around the nucleus by the electromagnetic force.

There are some atoms which have unstable nucleus such that the nucleus is either too big to hold itself together or has too many protons or neutrons to hold. In such cases, the nucleus has to get rid of such excess mass or particles which has been through radiation and the atoms whose nuclei undergo such radiation are called radioactive atoms. The unstable atoms continue to be radioactive until they lose enough mass/particles that they become stable. There are three types of radioactive decay:

Alpha Decay

Alpha decay happens when an atom is too big and need to get rid of some mass by shooting out a particle having two protons and two neutrons; that is a helium nucleus. This shooting out a helium nucleus resulting an element with atomic number two less than before.

Beta Decay

Beta decay happens when an atom has either too many protons or too many neutrons and need get rid of either of two ways; when a neutron turns into a proton (Beta-minus decay) or when a proton turns into a neutron (Beta-plus decay). When a neutron turns into a proton, the atom shoots out an electron that resulting to an element with one higher atomic number than before. Or when a proton turns into a neutron, the atom shoots out a positron that resulting to an element with one lower atomic number than before.

Gamma Decay

Gamma decay is when an atom shoots out a gamma ray or wave. It happens when there is a change in the energy of the nucleus which had already gone through alpha or beta decay. After a nucleus undergone through alpha decay or beta decay, it is usual that there is no change in the mass or atomic number or the atom; but there is a change only in the stored energy inside the nucleus.