Basic Atomic Structure Worksheet (You must use a Periodic Table of the Elements)
1. Define nucleon.
2. Define mass number, A.
3. Define atomic number, Z.
4. What are the relative masses of a proton, a neutron and an electron?
5. Describe how you calculate the number of neutrons of an isotope from its mass number(A) and its atomic
number(Z).
6. The 3 particles of the atom are:
a. ________________________ b. ________________________ c. ________________________
Their respective charges are:
a. ________________________
b. ________________________
c. ________________________
2. The number of protons in one atom of an element determines the atom’s ____________________, and the
number of electrons determines the _________________________ of the element.
3. The atomic number tells you the number of ___________________________ in one atom of an element. It
also tells you the number of __________________________ in a neutral atom of that element. The atomic
number gives the “identity” of an element as well as its location on the periodic table. No two different elements
will have the ____________________ atomic number.
4. The ______________________ of an element is the average mass of an element’s naturally occurring atom,
or isotopes, taking into account the ____________________ of each isotope.
5. The _______________________ of an element is the total number of protons and neutrons in the
___________________ of the atom.
6. The mass number is used to calculate the number of ______________________ in one atom of an element.
In order to calculate the number of neutrons you must subtract the ______________________ from the
___________________.
7. Given the elements name and its mass number give the complete isotopic symbol and the number of neutrons
for the following:
Lithium-6 _____________________________
Iron-58 _____________________________
Oxygen-17 _____________________________
Krypton-78 _____________________________
Bromine-79 _____________________________
Copper-65 _____________________________
Mercury-200 _____________________________
Helium-3 _____________________________
8. Give the element symbol of and the number of electrons in a neutral atom of:
Uranium _____________________________
Boron _____________________________
Chlorine _____________________________
Iodine _____________________________
Xenon _____________________________
9. Name the element which has the following numbers of particles:
a. 26 electrons, 26 protons _________________________
b. 53 protons, 74 neutrons __________________________
c. 2 electrons (neutral atoms) ____________________________
d. 20 protons _____________________________
e. 86 electrons, 125 neutrons, 82 protons ____________________________
f. 0 neutrons _______________________________
10. If you know ONLY the following information can you ALWAYS determine what the element is? (Yes/No)
a. Number of protons ____________________________
b. Number of neutrons ___________________________
c. Number of electrons in a neutral atom ___________________________
d. Number of electrons _________________________
11. Fill in the missing items in the table below.
Complete the table. Use a periodic table where needed. There is enough information given for each element to
determine all missing numbers.
Symbol
23
Atomic
Number(Z)
Mass
Number(A)
Number of
Protons
Number of
Electrons
Na
K
40
19
38
38
F
41
18
50
131
52
10
20
26
Number of
Neutrons
50
I
Mg
109
47
46
72
1
2
1
36
S
26
27
23
32
Al
2
4
Cr
2
53
The Bohr Atom
1. Draw the structure of the Bohr atom and label all the parts. Include the energy levels with their n values.
2. If the energy of the lowest energy state of the Bohr atom is n=1 what energy does the electron have in
this level? How much energy does it take to just ionize a Bohr atom where the electron is in the n=1 state?
3. Do the positions of the energy levels change among the three hydrogen isotopes proteum, deuterium and
tritium?
Mass Determination of the Elements:
1. Which ion would be deflected most in a mass spectrometer?
a) 35Cl+
b) 37Cl+
c) 37Cl2+
2. Ionization, vaporization, deflection, acceleration, and detection are the steps in getting a mass spectrum
but placed in random order. Place the steps in the correct order.
3. Cations are _______( + or -) ions and anions are ________(+ or -) ions.
4. Why are relative atomic masses used and why is 12C used as a standard?
5. Please use the following table to calculate the average atomic mass of chlorine.
Isotope
35
Cl
37
Cl
6.
% Abundance
75.78%
24.22%
Mass (amu)
34.969
36.966
a)Use the following table to calculate the average atomic mass of Neon.
Isotope
20
Ne
21
Ne
22
Ne
% Abundance
90.48
0.27
9.25
Mass (amu)
19.992
20.993
21.991
b) What is the mass of a mole of Neon which contains all these isotopes of Ne?
23
Na is the only form of sodium that exists. It has a mass of 22.989amu. What is the atomic mass of
7. 11
elemental Na in amu and what is the mole mass of sodium.
Nuclear Radiations: Complete the following and answer questions.
1.
226
Rn → _____ + α
2. What element undergoes alpha decay to form lead-208?
3.
131
4.
81
5.
238
I → 131Xe + _____
Rb +
e → _____
U → _____ + α + 2
e
6. How does gamma radiation change the atomic number and/or mass number of a nucleus?
Electronic Structure of the Atoms.
7. When or under what conditions are  particles emitted from an atom. What is the symbol of an alpha
particle?
8. When or under what conditions are  particles emitted from an atom. What is the symbol of a beta
particle?
Electron Structure
1. Draw the Bohr model for hydrogen with a single electron. Show the n=1, n=2, n=3 energy levels
with the electron in the first or lowest level. Label the diagram.
Li
Ar
Na
Na+
Cl-
2. Use the diagram above to draw the electron configuration of Li, Ar and Na to the right side of the
page.
3. Use the diagrams above for Li, Ar, and Na and write the symbolic notation for the electron structure
of Na, Ar, and Na. Example: 3Li is 1s22s1 .
4. Use the diagram above to draw the electron configuration of the ions: Na+ and Cl- also to the right
side of the page.
5. Use the diagrams above for Li, Ar, and Na and write the symbolic notation for the electron structure
of Na+, and Cl-.
6. What does the l quantum number tell us about an electron-suborbital?
The Light Spectrum
1.What color has the lowest energy in the visible spectrum.
2. What color has the highest energy in the visible spectrum.
3. What is the spectrum called at lower energies than red.
4. What is the spectrum called at higher energies than violet.
5. Write the relationship between energy and frequency of light.
6. Name the three series of light emitted by the hydrogen atom.