3.1.1.2 Mass number and isotopes- Mass number

Question 1

why atoms of an element may have different mass numbers

Answer 1

They may have different numbers of neutrons

Question 2

Definition: mass number of an atom

Answer 2

P+n / number of nucleons (protons and neutrons)

Question 3

Definition: relative molecular mass

Answer 3

Mean /average mass of a molecule/entity/formula

1 l/12th mass of atom of 12C

Question 4

number of neutrons in one atom of 65Cu

Answer 4

36

Question 5

Definition: relative atomic mass of an element

Answer 5

mean /average mass of an atom / all the isotopes;

l/12th mass of atom of 12C ;

Question 6

Definition: atomic number of an element

Answer 6

number of protons in one atom or nucleus

Question 7

Definition: relative atomic mass of an element

Answer 7

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

Question 8

Definition: atomic number of an atom

Answer 8

number of protons

Question 9

Definition: relative atomic mass of an element

Answer 9

(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

Question 10

Definition: mass number

Answer 10

the number of protons and neutrons / number of nucleons in the nucleus / atom

Question 11

Definition: relative atomic mass

Answer 11

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

Question 12

the number of protons in 82W

Answer 12

74

Question 13

the number of neutrons in 86W

Answer 13

112

Question 14

Definition: atomic number

Answer 14

Number of protons in the nucleus

Question 15

Definition: relative atomic mass

Answer 15

(mean mass of an atom/mass of one atom og 12C) x12

Question 16

number of protons present in an atom of 54Cr

Answer 16

Protons = 24

Question 17

the number of neutrons present in an atom of 52Cr

Answer 17

Neutrons = 28

Question 18

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

Answer 18

Need (relative) abundance or peak height or intensity / amount / number / % / fraction of each element