Question

) Calculate the atomic weight of Cerium Ce when the following information is known. Show all calculation steps you have used:

Isotope	Atomic Mass	Natural Abundance
136Ce	135.907amu	0.185%
138Ce	137.906amu	0.251%
140Ce	139.905amu	88.45%
142Ce	141.909amu	11.11%

5pts.

2)

a) What elements in the periodic table tend to lose electrons?

b) What elements in the periodic table tend to gain electrons?

c) What is the name for the following ionic species:

a)         BrO₄^-

b)         IO₂^-

c)         Au³

Answer 1

1) atomic weight = [sum of(atomic mass of isotope x isotopic abundance%)]/100

= [(135.907 x 0.185) + (137.906 x 0.251) + (139.905 x 88.45) + (141.909 x 11.11)]/100

= [25.143 + 34.614 + 12374.597 + 1576.609 ]/100

= 140.10963 g

2)

a) Element which tend to loose electrons in the periodic table : Metals loose electrons

b) Element which tend to gain electrons in the periodic table : Non-metals gain electrons

c) Name of the ionic species,

a) BrO4- : perbromate ion

b) IO2- : iodite ion

c) Au3 : auric ion