WS#02 Atoms Molecules and Ions (Chapter 2 openstax Chemistry-Atoms First) [Key].pdf

Worksheet 2: Atoms, Molecules and Ions (Chapter 2; openstax: Chemistry Atoms First)
Topics covered in this worksheet: atomic structure basics, symbolism, isotopes, the periodic table, naming of
compounds, the concept of mole, atomic and molecular mass.
Symbol to represent isotope;
Where, A = Mass number = # Protons + # Neutrons and Z = Atomic Number = # Protons
1. Using the Periodic Table, fill in the missing information in the chart, below.
Symbol atomic mass protons neutrons electrons charge
W 184 74 110 72 2+
Br 80 35 45 35 0
Au 197 79 118 78 +
Te 128 52 76 54 2-
2. For each of the numbered species that is a neutral atom, represent its composition in the form
Which of these species are isotopes? Explain why?
#1 #2 #3 #4 #5 #6 #7
protons 16
20
19 18 20
22 20
neutrons 18 20 21 22 24 26 28
electrons 18
20
18 17 18
22
20
X
A
Z
X
A
Z
Ca
40
20
Ca
48
20
Neutral
atom