The formula weight is simply the weight in atomic mass units of all the atoms in a given formula. When calculating molecular weight of a chemical compound, it tells us how many grams are in one mole of that substance. Find high-quality stock photos that you wont find anywhere else. 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.įinding molar mass starts with units of grams per mole (g/mol). Search from Mass Of A Helium Atom stock photos, pictures and royalty-free images from iStock. These relative weights computed from the chemical equation are sometimes called equation weights. For bulk stoichiometric calculations, we are usually determining molar mass, which may also be called standard atomic weight or average atomic mass.įormula weights are especially useful in determining the relative weights of reagents and products in a chemical reaction. This is not the same as molecular mass, which is the mass of a single molecule of well-defined isotopes.
#Atomic mass of helium how to#
This is how to calculate molar mass (average molecular weight), which is based on isotropically weighted averages.
The atomic weights used on this site come from NIST, the National Institute of Standards and Technology. Name: Helium Symbol: He Atomic Number: 2. 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. It has two protons and two electrons in its nucleus. If the formula used in calculating molar mass is the molecular formula, the formula weight computed is the molecular weight. Helium is an inert gas which is the simplest and foremost compound in the group of inert gases. Because of the weak, induced dipoledipole interaction between the helium atoms, their microscopic physical properties are mainly determined by their zero-point energy. This site explains how to find molar mass. Because of its low atomic mass of 3.016 u, helium-3 has some physical properties different from those of helium-4, with a mass of 4.0026 u. The reason is that the molar mass of the substance affects the conversion. To complete this calculation, you have to know what substance you are trying to convert.
Then, the remaining mass (4 - 2) u 2 u is contributed by 2 neutrons. Since helium atom has two protons, mass contributed by the two protons is (2u 2 u. (carbon twelve) is defined as 12 amu so, this is an exact number. The mass of an atom is the sum of the masses of protons and neutrons present in its nucleus. 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.Ī common request on this site is to convert grams to moles. Atomic mass is based on a relative scale and the mass of 12C.