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Atomic Number & Isotopes
(std.1.A)
Figure A shows isotopes of a Helium atom.
Answer the following questions:
1. What makes all 4 of these atoms isotopes of each
other?
2. How are these isotopes different from each other?
Figure A
3. Identify the number of protons, neutrons, and electrons
in each atom.
4. What does the number in front of the element
represent?
5. What is the net charge of each atom? Explain.
Short Response:
Explain why helium can have 4 mass numbers but is represented
on the periodic table as 4.0026 a.m.u.
Complete the following table
Isotope
Atomic number
Mass number
Number of protons
32
16
Number of neutrons
Number of electrons
Potassium-41
17
Figure B shows a periodic square and part of the periodic
table. Answer the following questions:
1. Identify the following letters with the correct terms:
A. _______________________
B. _______________________
C. _______________________
D. _______________________
2. Take a look at the atomic number for all the elements
on the periodic table. How are the elements arranged?
3. Circle specific examples on the periodic table why it is
NOT arranged by increasing atomic mass.
20
Figure B
Atoms & Isotopes (cont.)
(HONORS)
Figure C
(Figure C) Relationship between
Atomic Mass and Mass Number
1. Titanium is known to have 5 common isotopes:
(Ti-46) (Ti-47)(Ti-48) (Ti-49) (Ti-50)
Which based on the atomic mass of Titanium on the
periodic table, which of these isotopes do you believe is
most abundant?
2. Explain your answer in the question above.
(Figure D) Calculating the Atomic Mass
of an Unknown Element
3. An element has three naturally occurring isotopes.
Solve for the atomic mass of this element.
4. Identify the element above.
Figure D
Isotope
X-16
X-17
X-18
Percent Abundance
99.762
0.038
0.2