Atomic Theory

2. Radiation: A type of radiation where a neutron in the nucleus decays into a proton and an electron (beta particle). The proton stays in the nucleus, and the electron is emitted.
3. Ray: High-energy electromagnetic radiation emitted from the nucleus of an atom during radioactive decay. Gamma rays have no charge and no mass, but they carry a lot of energy.
5. The dense, positively charged center of an atom that contains protons and neutrons. It is where most of the atom's mass is concentrated.
6. Variants of the same element that have the same number of protons but different numbers of neutrons, leading to different atomic masses.
9. Number: The number of protons in the nucleus of an atom. It defines the element and its position on the periodic table.
10. The process by which unstable atomic nuclei lose energy by emitting radiation. This can occur in the form of alpha particles, beta particles, or gamma rays.
13. A negatively charged subatomic particle that orbits the nucleus of an atom. Electrons are involved in chemical bonding and reactions.

1. The smallest unit of an element that retains the properties of that element. It consists of a nucleus surrounded by electrons.
4. Mass: The weighted average mass of an atom of an element, considering the different isotopes and their abundances.
5. A neutral (uncharged) subatomic particle found in the nucleus of an atom. Neutrons and protons have roughly the same mass.
7. A positively charged subatomic particle found in the nucleus of an atom. The number of protons determines the element's identity (its atomic number).
8. Model: A model of the atom proposed by Niels Bohr. It describes the atom as having a central nucleus surrounded by electrons that orbit the nucleus in specific energy levels or shells. This model helps explain the atom’s energy levels and electron transitions.
11. Mass Unit (amu): A unit of mass used to express atomic and molecular weights. It is defined as one twelfth of the mass of a carbon-12 atom.
12. Radiation: A type of radiation where an atom emits an alpha particle (2 protons and 2 neutrons) from its nucleus. This results in a new element with a lower atomic number.