From Citizendium, the Citizens' Compendium
- Chemistry : The science of matter, or of the electrical or electrostatical interactions of matter.
- Biology : The science of life — of complex, self-organizing, information-processing systems living in the past, present or future.
- Chemical elements : In one sense, refers to species or types of atoms, each species/type distinguished by the number of protons in the nuclei of the atoms belonging to the species/type, each species/type having a unique number of nuclear protons; in another sense, refers to substances, or pieces of matter, each composed of multiple atoms solely of a single species/type.
- Periodic table of elements : A tabular method of displaying the chemical elements.
- Atomic electron configuration : A specification of the occupation of an atom's electron orbitals by electrons.
- Atomic mass : The mass of an atom expressed in unified atomic mass units (u) and formerly known as atomic weight.
- Atomic number : The number of protons in the nucleus of a single atom of a chemical element.
- Atomic radius : A measure of the size of an atom, usually the distance from the nucleus to the boundary of the surrounding cloud of electrons.
- Cell (biology) : The basic unit of life, consisting of biochemical networks enclosed by a membrane.
- Chemical symbol : A shorthand for denoting chemical elements, e.g. in the Periodic Table of Elements or in chemical formulas and equations.
- Magnesium : The metallic element that has atomic number 12 and belongs to alkaline earth metal group.
- Potassium : A very reactive, silvery white alkali metal, chemical element 19 with symbol K.
- Mineral : Add brief definition or description
- Proton : A subatomic particle with an electric charge of +1 elementary charge.
- Oxidation state : A measure of the degree of oxidation of an atom in a substance.
- Scandium : A silvery-white metallic transition metal, with symbol Sc and atomic number 21.
- Strontium : A chemical element, having the chemical symbol Sr, and atomic number (the number of protons) 38.