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M N−1. In chemistry, the molar mass (M) (sometimes called molecular weight or formula weight, but see related quantities for usage) of a chemical compound is defined as the ratio between the mass and the amount of substance (measured in moles) of any sample of the compound. [1] The molar mass is a bulk, not molecular, property of a substance.
The number of particles in a mole is the Avogadro number (symbol N 0) and the numerical value of the Avogadro constant (symbol N A) expressed in mol-1. [1] The value was chosen on the basis of the historical definition of the mole as the amount of substance that corresponds to the number of atoms in 12 grams of 12 C, [1] which made the mass of ...
Atomicity (chemistry) Atomicity is the total number of atoms present in a molecule of an element. For example, each molecule of oxygen (O 2) is composed of two oxygen atoms. Therefore, the atomicity of oxygen is 2. [1] In older contexts, atomicity is sometimes equivalent to valency. Some authors also use the term to refer to the maximum number ...
The molecular mass (m) is the mass of a given molecule. Units of daltons (Da) are often used. [1] Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The derived quantity relative molecular mass is the unitless ratio of the mass of a molecule to the atomic mass ...
The Avogadro constant, commonly denoted N A [1] or L, [2] is an SI defining constant with an exact value of 6.022 140 76 × 10 23 mol −1 (reciprocal moles). [3] [4] It is defined as the number of constituent particles (usually molecules, atoms, ions, or ion pairs) per mole and used as a normalization factor in the amount of substance in a sample.
A given atom has an atomic mass approximately equal (within 1%) to its mass number times the atomic mass unit (for example the mass of a nitrogen-14 is roughly 14 Da), but this number will not be exactly an integer except (by definition) in the case of carbon-12. [67] The heaviest stable atom is lead-208, [59] with a mass of 207.976 6521 Da. [68]
The unit of amount of substance in the International System of Units is the mole (symbol: mol), a base unit. [1] Since 2019, the value of the Avogadro constant NA is defined to be exactly 6.022 140 76 × 1023 mol−1. Sometimes, the amount of substance is referred to as the chemical amount or, informally, as the " number of moles " in a given ...
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...