CALCULATIONS- relative atomic mass & isotopes

Question 1

2 types of chlorine (isotopes)

Answer 1

Cl 35                          Cl 37
     17                               17
 75%                           25%
(75/100 x 35)             (25/100 x 37)
  =26.25                       =9.25
                      \+
=35.5

Question 2

RELATIVE ATOMIC MASS

Answer 2

the average of isotopes

Question 3

isotopes

Answer 3

atoms of the same element,
that have the same number of protons,
but a different number of neutrons

change electrons= ions
change neutrons= isotopes

different isotopes will have different masses but they will react the same because the outer shell electrons determine their reactivity.