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ATOMS
Atoms: The building blocks of matter from the Elements of Chemistry Series
Term | Definition |
---|---|
alpha radiation | All radiation occurs when the nucleus of an atom decomposes to form a new nucleus. It consists of helium nuclei, two protons, and two neutrons. |
atom | The fundamental (not smallest) unit of matter in the universe, made up of a nucleus of protons and neutrons and orbiting electrons. |
atomic number | The number of an element is determined by the number of protons in its nucleus. |
atomic mass | The mass of the element |
atomic mass unit (amu) | This is a measurement of the atomic mass. One amu is roughly equal to the mass of one proton. |
beta radiation | It occurs when high-speed electrons decompose from the nucleus. |
Bohr, Niels | Danish physicist, 1885 - 1962 Developed Planetary Model of atoms. |
DeBroglie, Louis | French physicist, 1892 -1987 derived an equation that describes the wavelength of a moving particle. |
electron | Negatively charged particle that orbits the nucleus of atoms. |
element | An atom with a unique number of protons. |
energy | In physics and chemistry, work, or the capacity to do work. |
energy levels | Electrons orbit here. They are sometimes called shells or just levels. |
fourth quantum number | Refers to the spin of the electron. |
fission | When the nucleus of atoms are split apart, releasing energy |
fusion | When two hydrogen atoms fuse under extreme heat, energy is released. It is the energy of the sun and stars. |
gamma radiation | It is an energetic form of light similar to X-rays. It happens when the nucleus of an atom decomposes to form a new nucleus. |
Heigenberg, Werner | German physicist, 1901-1976 Introduced Uncertainty Principle. |
Hund's Rule of Maximum Multiplicity | Electrons fill the energy levels in regular patterns. They first fill the s orbitals, then the p, and so on. |
hydrogen | The element with the atomic number of one and symbol of H. It is the most common element in the universe. |
ion | An atom with more or less electrons than protons. |
isotopes | Atoms that have more or less neutrons than protons. |
matter | Material that makes up objects. It cannot be created or destroyed. |
mass | The total quantity of an object's matter. |
neutron | Particles in the nucleus of atoms that have no electrical charge. |
nuclear stability | An atom that is electrically neutral has an equal number of protons and electrons. |
nucleus | The center of an atom |
orbitals | The shapes of the orbits of electrons. |
oxidation numbers | Numbers indicating whether an ion has a positive or negative charge. |
oxygen | An element with atomic number of 8 and symbol of O. |
periodic table | The arrangement of elements according to their atomic number and group |
planetary model | The theory that electrons circle the nucleus of atoms like orbiting planets. Chemists and physicists abandoned this model when Quantum Theory was developed. |
principle quantum number | Often referred to as "n." This number refers to the energy of the orbitals. |
proton | Positively charged part of the nucleus of atoms. |
quanta | Quantities of energy |
quantum numbers | Four numbers that describe the motion of electrons. |
Quantum Theory | The theory that explains matter and energy at atomic and sub-atomic levels, sometimes called Quantum Mechanics. |
quarks | Sub-atomic particles of matter. There are six different types of quarks but only two occur in the nucleus of atoms. |
radioactive decay | Occurs when the original nucleus of an element decomposes to form a new nucleus, releasing radiation. |
Rutherford, Earnest | British physicist (New Zealand), 1871 -1937. According to his model, all of an atom's positive charge is concentrated in its nucleus. |
second quantum number | Refers to the shape of the orbital. |
strong nuclear force | The force that holds the nucleus of atoms together. It is one of the fundamental forces of the universe. |
third quantum number | Refers to the orientation of the orbital. |
Thomson, J. J. | British physicist, 1856- 1937 His experiment provided the first evidence that atoms are made of even smaller particles. |
transuranium elements | These are 92 elements found naturally in the universe. Several elements, with atomic numbers greater than 92, have been created under laboratory conditions. They are called transuranium elements. |
Uncertainty Principle | The theory that it is impossible to know precisely the location and velocity of electrons at the same time. |