U1L1: The Nature of Atoms and the Atomic Structure Worksheet
1. Fill in the blanks with the appropriate information. Use your periodic table to determine what element it is
(Assume that the atoms of each element are neutral)
Element
Ag
Silver
As
Arsenic
Br
Bromine
Au
Gold
Sn
Tin
Atomic #
47
Mass #
108
# of protons
47
# of electrons # of neutrons
47
61
33
75
33
33
42
35
80
35
35
45
79
179
79
79
100
50
119
50
50
69
THE ATOMIC NATURE OF MATTER
MODEL 1:
Atoms (Adapted from PhET Simulations)
Open the Atomic Nature simulation https://phet.colorado.edu/en/simulation/build-an-atom
Explore the Atom part of the simulation. You can drag as many neutrons, protons and electrons into the center
of the atom model.
1. Click on the + sign for each of the yellow boxes (element name, net charge and mass number) to view
changes as you change the number of particles in the atom.
2. What particle(s) are found in the center of the atom?
Protons and neutrons
3. What is the name of the following atoms?
a. An atom with 2 protons and 3 neutrons: _______Helium______
b. An atom with 2 protons and 7 neutrons: _______Helium______
c. An atom with 4 protons and 4 neutrons: _______Beryllium______
4. We will be learning about charge of an atom or ion in our next lesson. To get you started, play with the
simulation to discover which particles affect the charge of an atom or ion: ___the number of electrons
affects the charge of an atom or ion__________
5. Fill in the blanks below to show your results:
a. Neutral atoms have
the same number of
protons and electrons.
b. Positive ions have ____more number of_____ protons than electrons.
c. Negative ions have _____less number of____ protons than electrons.
6. Play with the simulation to discover what affects the mass number of your atom or ion. ___________the
number of protons and neutrons affect the mass number.____________
a. What is a rule for determining the mass number of an atom or ion?
The mass number = the number of protons + the number of neutrons
MODEL 2:
Symbol (Adapted from PhET Simulations)
1. Using the Symbol readout box, figure out which subatomic particles affect each component of the atomic
symbol and how the value of the numbers is determined.
d
c
b
a
Position in symbol box
Term to describe this
information
Particle used to
determine this
How the value is
determined
a
Element symbol
protons
# of p will identify the
element
b
Charge
Protons, electrons
p+ + e-
c
Atomic number
protons
# of p
d
Mass number
Protons, neutrons
# of p + # of n
2. Create a definition (using a complete sentence) for each of these items based on your labels from the atomic
symbol above.
a. Element Symbol
1. The symbol that represents the element in a periodic table
b. Charge
The number of protons + the number of electrons that characterize element’s positive or negative
electric force.
c. Atomic Number
The number of protons in an atom
d. Mass Number
The number of protons + the number of neutrons in an atom
3. In addition to atomic symbol, we can represent atoms by name and mass number. Complete the table
below:
Symbol
Name
C+1
Carbon-12
18
9
F
Fluorine-18
11
5
B
Boron-11
12
6
1. How will you use your periodic table to find the number of neutrons?
The number of neutrons and the mass number are shown in the periodic table. Then, I can find the number
of neutrons by subtracting the number of protons from the mass number.
2. How can you use your periodic table to find the number of electrons in a neutral element?
The number of protons is the same as the number of electrons in a neutral element. So, I can find the
number of electrons in a periodic table by seeing the number of protons.