Atomic Mass of Bromine Atomic mass of Bromine is 79.904 u. Note that, each element may contain more isotopes, therefore this resulting atomic mass is calculated from naturally-occuring isotopes and their abundance. The unit of measure for mass is the atomic mass unit (amu). Bromine is a chemical element with atomic number 35 which means there are 35 protons and 35 electrons in the atomic structure. The chemical symbol for Bromine is Br. Bromine is the third-lightest halogen, and is a fuming red-brown liquid at room temperature that evaporates readily to form a similarly coloured gas.
| Isotope | Atomic mass (Da) | Isotopic abundance (amount fraction) |
|---|---|---|
| 79Br | 78.918 338(7) | [0.505, 0.508] |
| 81Br | 80.916 288(6) | [0.492, 0.495] |
In 1961, the Commission recommended Ar(Br) = 79.909(2) based on a chemical determinationof the mass ratio AgBr/Ag and an updated evaluation of the atomic weight of silver, which was then the major source of the uncertainty in Ar(Br). The values of Ar(Br) and Ar(Ag)were especially important at that time because the atomic weights of many other elements were determinedby the mass ratios of their bromides to Ag or AgBr. In its 1965 re-evaluation, summarized in the1967 report, the Commission adopted the recent mass-spectrometric measurements, which yielded Ar(Br) = 79.904(1) and essentially ended the era of chemical determinations ofatomic weights for this element.
- The element bromine, Br (atomic number 35), has two major isotopes of similar abundance, both around 50 percent. The atomic mass of bromine is reported in the periodic table as 79.904 atomic mass units. Choose the most likely set of mass numbers for these two bromine isotopes.
- Two naturally existing isotopes of bromine exist, bromine-79 and bromine-81. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number.
- Bromine is a chemical element with atomic number 35 which means there are 35 protons and 35 electrons in the atomic structure. The chemical symbol for Bromine is Br. The atom consist of a small but massive nucleus surrounded by a cloud of rapidly moving.
The standard atomic weight of bromine was last revised in 2011 to better reflect the natural variations of Ar(Br) in natural materials.
Atomic weights of the elements 2011 by M.E. Wieser et al. Pure Appl. Chem. 2013 (85) 1047-1078
CIAAW
Bromine
Ar(Br) = [79.901, 79.907] since 2011
The name derives from the Greek bromos for 'bad stench' or 'bad odour'. It was first prepared by theGerman chemist Carl Löwig in 1825, but it was first publicly announced in 1826 by the French chemistand pharmacist Antoine-Jérôme Balard, and so the discovery is, therefore, credited to him.
Natural variations of bromine isotopic composition
Isotopic reference materials of bromine.
Molar mass of KBr = 119.0023 g/mol
This compound is also known as Potassium Bromide.
Bromine Relative Atomic Mass
Convert grams KBr to moles or moles KBr to grams
Molecular weight calculation:
39.0983 + 79.904
| Symbol | # of Atoms | Bromine | Br | 79.904 | 1 | 67.145% | |
| Potassium | K | 39.0983 | 1 | 32.855% |
In chemistry, the formula weight is a quantity computed by multiplying the atomic weight (in atomic mass units) of each element in a chemical formula by the number of atoms of that element present in the formula, then adding all of these products together.
Finding molar mass starts with units of grams per mole (g/mol). When calculating molecular weight of a chemical compound, it tells us how many grams are in one mole of that substance. The formula weight is simply the weight in atomic mass units of all the atoms in a given formula.
Bromine Atomic Mass Number
The atomic weights used on this site come from NIST, the National Institute of Standards and Technology. We use the most common isotopes. This is how to calculate molar mass (average molecular weight), which is based on isotropically weighted averages. This is not the same as molecular mass, which is the mass of a single molecule of well-defined isotopes. For bulk stoichiometric calculations, we are usually determining molar mass, which may also be called standard atomic weight or average atomic mass.
A common request on this site is to convert grams to moles. To complete this calculation, you have to know what substance you are trying to convert. The reason is that the molar mass of the substance affects the conversion. This site explains how to find molar mass.
If the formula used in calculating molar mass is the molecular formula, the formula weight computed is the molecular weight. The percentage by weight of any atom or group of atoms in a compound can be computed by dividing the total weight of the atom (or group of atoms) in the formula by the formula weight and multiplying by 100.
Using the chemical formula of the compound and the periodic table of elements, we can add up the atomic weights and calculate molecular weight of the substance.
Formula weights are especially useful in determining the relative weights of reagents and products in a chemical reaction. These relative weights computed from the chemical equation are sometimes called equation weights.