Relative masses Flashcards
Atomic/ proton number
Number of protons in the nucleus of an atom of that element.
(If an uncharged atom it would show the number of electrons too)
Z symbol
Atomic (proton) number
Mass number/ nucleon number
A total of the number of protons and neutrons in the nucleus of that element
A symbol
Mass number
Isotopes
atoms of the same element with the same number of protons but a different number of neutrons
Relative isotopic mass
Mass number of an individual atom of an isotope compared to 1/12 the mass of a carbon-12 atom.
(Used in the context of isotopes)
Relative atomic mass
The mean mass of an atom of an element compared to 1/12 the size of a carbon-12 atom
Ar symbol
Stands for relative atomic mass
How to find the relative atomic mass given the abundance
Add up (not multiply):
Relative isotopic mass x % abundance
Of all isotopes given
Divide by 100
Molecular formula
Tells us which and how many atoms of which element in a covalent/ simple molecule
Eg CO2
Empirical formula
Tells us the simplest whole number ratio of atoms of which element is in the compound
Includes giant structures: ionic lattices or giant covalent and simple
Why do we use empirical formula?
It’s an easier way to represent which and how many atoms are in a compound without writing out the very large number
Relative molecular mass
The weighted mean mass of a molecule compound compared to 1/12 a carbon-12 atom, calculated by adding the relative atomic masses of each atom
Relative formula mass
Weighted mean mass of a compound’s empirical formula with 1/12 the mass of a carbon-12 atom
Useful for giant structures (ionic or covalent)
Add up the masses as shown in the empirical formula
Symbol for relative formula mass and relative molecular mass
The same = Mr