Periodic Table of Elements
A principle discovered by the Greek mathematician Archimedes which states that the volume of a solid is equal to the volume of water it displaces.
The number of protons in the nucleus of an atom.
A model of atomic structure developed by Niels Bohr, a Danish scientist. In this model, electrons occur in orbits of differing energy levels around the nucleus of an atom.
The change in the physical state of matter from a gaseous state to a liquid state.
The change in the physical state of matter from a gaseous state to a solid state without ever becoming a liquid. The reverse of sublimation.
Substances that can conduct electricity either in the molten state or when dissolved in water.
A method used by chemists to represent electrons in bonding and chemical reactions.
A measure of an atom’s strength to attract a bonding pair of electrons to itself.
A method used by chemists to diagram the electrons for an atom (including orbitals and subshells) in bonding and chemical reactions.
A mixture whose composition varies from position to position within a sample.
A mixture whose composition is the same from position to position within a sample.
Atoms of the same element that have varying numbers of neutrons.
The sum of the protons and neutrons in a particular isotope; also called atomic weight.
Substances that do not conduct electricity in the molten state or when dissolved in water.
A nuclear reaction in which an atom’s nucleus splits into smaller parts.
A process in which lighter nuclei of atoms join together into a heavier nucleus; essentially the opposite of nuclear fission.
Any reaction that involves a change in nuclear structure.
A table that displays all known chemical elements in an arrangement that is based on the properties of the elements; changes over time as new elements are discovered.
A model of atomic structure that is based on mathematics and can be used to explain observations made on complex atoms.
The spontaneous decay of an unstable nucleus in an atom.
A worldwide measurement system that is based on the older metric system. The SI comes from the French Systeme International.
The change in the physical state of matter from a solid state to a gaseous state without ever becoming a liquid (such as dry ice).
The electrons in the outermost energy level of an atom, the farthest away from the nucleus.