The atomic number or nuclear charge number (symbol Z) of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of...

mass number (symbol A, from the German word: Atomgewicht, "atomic weight"), also called atomic mass number or nucleon number, is the total number of protons...

is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). The definitive visualisation of...

lowest mass) has an atomic weight of 1.007825 Da. The value of this number is called the atomic mass. A given atom has an atomic mass approximately equal...

atomic number, denoted by Zeff, may refer to: Effective nuclear charge of an individual atom, as felt by electrons within that atom Effective atomic number...

numeric value of the atomic mass when expressed in daltons has nearly the same value as the mass number. The value of 1 unified atomic mass unit in kilograms...

The atomic number of a material exhibits a strong and fundamental relationship with the nature of radiation interactions within that medium. There are...

and organizes. Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on. Each of these names can be further...

(or nuclides) of the same chemical element. They have the same atomic number (number of protons in their nuclei) and position in the periodic table (and...

Boron is a chemical element; it has symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous...

) is a chemical element; it has symbol Pb (from Latin plumbum) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead...

(from Latin carbo 'coal') is a chemical element; it has symbol C and atomic number 6. It is nonmetallic and tetravalent—meaning that its atoms are able...

have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8: each oxygen...

chemical element; its chemical symbol is Au (from Latin aurum) and atomic number 79. In its pure form, it is a bright, slightly orange-yellow, dense...

Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table...

Hydrogen is a chemical element; it has symbol H and atomic number 1. It is the lightest and most abundant chemical element in the universe, constituting...

Oxygen is a chemical element; it has symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal...

In quantum mechanics, an atomic orbital (/ˈɔːrbɪtəl/ ) is a function describing the location and wave-like behavior of an electron in an atom. This function...

Neon is a chemical element; it has symbol Ne and atomic number 10. It is the second noble gas in the periodic table. Neon is a colorless, odorless, inert...

The atomic radius of a chemical element is a measure of the size of its atom, usually the mean or typical distance from the center of the nucleus to the...

Beryllium is a chemical element; it has symbol Be and atomic number 4. It is a steel-gray, hard, strong, lightweight and brittle alkaline earth metal...

λίθος, líthos, 'stone') is a chemical element; it has symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions...

especially difficult to measure accurately. Graphs of abundance against atomic number can reveal patterns relating abundance to stellar nucleosynthesis and...

The neutron number (symbol N) is the number of neutrons in a nuclide. Atomic number (proton number) plus neutron number equals mass number: Z + N = A....

Atomic theory is the scientific theory that matter is composed of particles called atoms. The definition of the word "atom" has changed over the years...

which had the temporary name of unniloctium, based on the digits of its atomic number. There are also some historical symbols that are no longer officially...

discovered, the atomic masses had been determined to be (approximately) integer multiples of the mass of the hydrogen atom, and the atomic number had been identified...

In atomic physics, the effective nuclear charge of an electron in a multi-electron atom or ion is the number of elementary charges ( e {\displaystyle...

The standard atomic weight of a chemical element (symbol Ar°(E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all...

Fluorine is a chemical element; it has symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as pale yellow diatomic...