Atoms
Basic building block of matter
Element
A chemical element is a chemical substance that cannot be broken down into other substances by chemical reactions.
Proton
A small, positively charged particle of matter found in the atoms of all elements.
Neutron
a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.
Electron
a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.
Atomic mass
the mass of an atom of a chemical element expressed in atomic mass units. It is approximately equivalent to the number of protons and neutrons in the atom
Atomic Number
the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.
Nuclear fisson
Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay.
Nuclear fusion
a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.
Radioactivity
the emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei.
Radioactive dating
Radiometric dating calculates an age in years for geologic materials by measuring the presence of a short-life radioactive element, e.g., carbon-14, or a long-life radioactive element plus its decay product, e.g., potassium-14/argon-40.
Radioactive decay
Radioactive decay is the emission of energy in the form of ionizing radiation. Ionizing radiation can affect the atoms in living things, so it poses a health risk by damaging tissue and DNA in genes.. The ionizing radiation that is emitted can include alpha particles.