3.1.1.2 Mass number and isotopes- Mass number Flashcards
why atoms of an element may have different mass numbers
They may have different numbers of neutrons
Definition: mass number of an atom
P+n / number of nucleons (protons and neutrons)
Definition: relative molecular mass
Mean /average mass of a molecule/entity/formula
1 l/12th mass of atom of 12C
number of neutrons in one atom of 65Cu
36
Definition: relative atomic mass of an element
mean /average mass of an atom / all the isotopes;
l/12th mass of atom of 12C ;
Definition: atomic number of an element
number of protons in one atom or nucleus
Definition: relative atomic mass of an element
average mass of an atom (or isotope) 12 (1) × 12 (1) Reference to mass number not mass C.E. = 0 OR stated in moles OR compared with 1/12 of a 12C atom or relative to 12C when taken as 12
Definition: atomic number of an atom
number of protons
Definition: relative atomic mass of an element
(or average) 12 mean atom mass of an atom (mass) 1 of C × 12 (1) (1) or (1) (1) 12 massof 1molof Catoms massof 1molof atoms 12 × or mean mass of an atom (1) or compared with {an atom of 12C taken as 12 { 12 1 of a 12C atom
Definition: mass number
the number of protons and neutrons / number of nucleons in the nucleus / atom
Definition: relative atomic mass
Mean (average) mass of an atom / all the isotopes or 1 1/12th mass of atom of 12C 1 Mass of 1mole of atoms of an element or 1/12th mass of 1mole of 12C average mass of an atom / all the isotopes Relative to the mass of a 12C atom taken as exactly 12 / 12.000
the number of protons in 82W
74
the number of neutrons in 86W
112
Definition: atomic number
Number of protons in the nucleus
Definition: relative atomic mass
(mean mass of an atom/mass of one atom og 12C) x12
number of protons present in an atom of 54Cr
Protons = 24
the number of neutrons present in an atom of 52Cr
Neutrons = 28
Apart from the relative mass of each isotope, what else would need to be known for the relative atomic mass of chromium to be calculated
Need (relative) abundance or peak height or intensity / amount / number / % / fraction of each element
