"The atomic mass (ma or m) is the mass of an atom."
Defines atomic mass as the weighted average mass of all the isotopes of an element and explains how it is calculated using isotopic abundances.
Atoms and elements: Atoms are the smallest units of matter that have the properties of an element. Elements are substances made up of only one type of atom.
Subatomic particles: Subatomic particles are the particles that make up atoms. The three subatomic particles are protons, neutrons, and electrons.
Atomic nucleus: The atomic nucleus is located at the center of an atom and is made up of protons and neutrons.
Atomic number: Atomic number is the number of protons in an atom's nucleus. It determines the identity of the element.
Isotopes: Isotopes are atoms of the same element that have different numbers of neutrons in their nucleus.
Mass number: Mass number is the sum of the number of protons and neutrons in an atom's nucleus.
Atomic mass unit: Atomic mass unit (amu) is a unit of measurement used to express the mass of atoms and molecules.
Atomic mass: Atomic mass is the mass of an atom, which is measured in atomic mass units.
Molar mass: Molar mass is the mass of one mole (6.02 × 1023) of atoms or molecules of a substance.
Periodic table: The periodic table is a tabular arrangement of the chemical elements, organized on the basis of their atomic number, electron configurations, and chemical properties.
Electron configuration: Electron configuration is the arrangement of electrons in an atom's orbitals.
Energy levels: Energy levels (or shells) are the regions surrounding an atom's nucleus where electrons are likely to be found.
Valence electrons: Valence electrons are the electrons in an atom's outermost shell that are involved in chemical bonding.
Chemical bonding: Chemical bonding is the attractive force that holds two or more atoms together in a molecule.
Ionic bonding: Ionic bonding is a type of chemical bonding that involves the transfer of electrons from one atom to another.
Covalent bonding: Covalent bonding is a type of chemical bonding that involves the sharing of electrons between atoms.
Isotopic abundance: Isotopic abundance is the relative amount of each isotope of an element in a sample.
Mass spectrometry: Mass spectrometry is a technique used to measure the mass-to-charge ratio of ions, which can be used to determine the atomic mass of an element.
Nuclear reactions: Nuclear reactions are reactions that involve changes in the atomic nucleus, typically through the emission or absorption of particles.
Radioactivity: Radioactivity is the spontaneous emission of ionizing radiation from the nucleus of an atom.
Atomic mass: The total mass of an atom, including protons, neutrons, and electrons.
Mass number: The number of protons and neutrons in the nucleus of an atom.
Isotopic mass: The mass of a specific isotope of an element, which is determined by the number of protons and neutrons in the nucleus.
Molecular mass: The mass of a molecule, which is the sum of the atomic masses of all the atoms in the molecule.
Average atomic mass: The weighted average of the masses of all the naturally occurring isotopes of an element, taking into account their relative abundances.
Relative atomic mass: The ratio of the mass of an atom of an element to the mass of an atom of carbon-12, which is assigned a value of exactly 12.
Standard atomic weight: The average atomic weight of an element based on the relative abundances of its isotopes in a sample of the element from a specified source.
Neutron number: The number of neutrons in the nucleus of an atom, which determines the isotope of the element.
Proton number: The number of protons in the nucleus of an atom, which determines the atomic number of the element.
"Atomic mass is often expressed in the non-SI unit dalton (symbol: Da) – equivalently, unified atomic mass unit (u)."
"1 Da is defined as 1⁄12 of the mass of a free carbon-12 atom at rest in its ground state."
"The protons and neutrons of the nucleus account for nearly all of the total mass of atoms."
"The electrons and nuclear binding energy make minor contributions."
"Thus, the numeric value of the atomic mass when expressed in daltons has nearly the same value as the mass number."
"Conversion between mass in kilograms and mass in daltons can be done using the atomic mass constant."
"1 Da = m_u = M_u / N_A = M(12C) / 12N_A = 1.66053906660(50) × 10^-27 kg,"
"M_u is the molar mass constant."
"N_A is the Avogadro constant."
"M(12C) is the experimentally determined molar mass of carbon-12."
"The relative isotopic mass can be obtained by dividing the atomic mass ma of an isotope by the atomic mass constant mu."
"Thus, the atomic mass of a carbon-12 atom is 12 Da by definition."
"The sum of relative isotopic masses of all atoms in a molecule is the relative molecular mass."
"The elemental atomic mass is the average (mean) atomic mass of an element, weighted by the abundance of the isotopes."
"The dimensionless atomic weight is the weighted mean relative isotopic mass of a (typical naturally occurring) mixture of isotopes."
"The atomic mass of atoms, ions, or atomic nuclei is slightly less than the sum of the masses of their constituent protons, neutrons, and electrons, due to binding energy mass loss."