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
Of a compound: the sum of the relative atomic masses of all the atoms in a molecule compared to one twelfth of the mass of one atom of carbon-12
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
Why do we measure the masses of an atom in the scale of 1/12 of a carbon-12 atom?
Because 1/12 a carbon atom is 1 amu
And we measure the relative masses using this measurement
Also because mass of atoms are so small any over unit wouldn’t work
Proton relative mass
1
Proton charge
1+
Proton location
Nucleus of atom
Neutron relative mass
1
Neutron charge
0
Neutron location
Nucleus of atom
Electron relative mass
1/1840
Electron charge
1-
Electron location
Orbitals
Nucleon
Collective term for neutrons and protons
What is the nucleon number
The same as mass number:
Protons + neutrons added together
How does the planet effect the calculated relative atomic mass of an atom of an element?
It is calculated weighted on the ratio of the isotope’s abundance found on Earth
This would change from rocks from space where the ratio and abundance is different
So by working out abundance of isotope = see where in space it came from
How do we find the abundance of different isotopes?
Technique called mass spectrometry
Do isotopes react the same way?
Yes because they have the same electron
Avogadros constant
The number of atoms, molecules, ions or other chemical entities in one mole of a substance. L = 6.02 x 1023
