Date
Name:
Build an Atom Activity
Directions:
1. Use Chrome to go to
https://phet.colorado.edu/en/simulation/build-an-atom
2. Click on the play button to open the simulation.
3. The program will open & click on ATOM
4. Take 5 minutes to explore the BUILD AN ATOM
simulation by placing some subatomic particles on the
atom.
5. Reset the simulation and then check the Stable/Unstable box in the bottom right corner.
6. Using the simulation, answer the following questions
a. Which particles (subatomic) go in the center of the atom?
b. What is the center of an atom called?
c. Play until you discover what makes the center of the atom “stable”.
What seems to make the center of the atom “unstable”?
2A I can compare and contrast the location, mass and charge of the three
subatomic particles within the structure of the atom.
Directions: Reset the simulation. First, Add 5 protons, 2 less electrons than protons and 6
neutrons to the simulation and use the net charge andmass number information on the right side
to fill in the table for protons. For Fill in the rest of the table for the other two subatomic
particles.
Subatomic
Particle
Proton
Neutron
Electron
Mass (a.m.u)
(atomic mass Charge
units)
Location within atom
Questions:
1. Which two subatomic particles have approximately the same mass?
2. Which two subatomic particles have the same location within the atom? Where?
3. Which subatomic particle has mass but no charge?
4. Which subatomic particle has charge but no mass?
5. Fill in the VENN DIAGRAM BELOW USING THE INFORMATION IN THE TABLE
Protons
Electrons
Neutrons
2B I can use the atomic number to identify the element and determine the number
of protons or electrons of an atom.
Directions: Everything around us is made up of different elements. The air has Oxygen and
Nitrogen. Plants and people have lots of Carbon. Helium is in balloons. Hydrogen is in water. In
this section you have to determine what factor determines the element an atom will be. Fill in the
table and then answer the questions that follow:
Example
1
2
3
4
Atom or Ion Has
What element is it?
# of protons: 6
# of neutrons: 6
# of electrons: 6
# of protons: 6
# of neutrons: 7
# of electrons: 6
# of protons: 7
# of neutrons: 6
# of electrons: 6
# of protons: 6
# of neutrons: 6
# of electrons: 7
Questions:
1. Looking at the table above, in which example did the element name change? Why do you
think that is?
_
_
2. Which subatomic particle determines the name of an element? Give another example from
the simulation (Test it by adding more of that particle and check if the name changes)
_
_
_
3. Compare the simulation to your periodic table to figure out where the number of protons of
an element is shown:
_
_
4. Use the simulation AND your reference guide to fill in the table below:
Element
Atomic Number
# of Protons
Fluorine
6
3
Calcium
Chlorine
79
Directions: Use a Play until you discover some good rules about the charge of your atom or ion. To
help you, fill in the table below by creating the neutral atoms and ions given below. List the
number of each subatomic particle in the table.
Neutral Carbon Atom
# of protons:
Positive Carbon Ion
# of protons:
Negative Carbon Ion
# of protons:
# of neutrons:
# of neutrons:
# of neutrons:
# of electrons:
# of electrons:
# of electrons:
Neutral Neon Atom
# of protons:
Positive Neon Ion
# of protons:
Negative Neon Ion
# of protons:
# of neutrons:
# of neutrons:
# of neutrons:
# of electrons:
# of electrons:
# of electrons:
.
Questions:
1. Which subatomic particle doesn’t affect the charge?
2. What is a good rule for making:
i.
A neutral atom which has no charge:
ii.
A positive ion which has positive charge:
iii.
A negative ion which has a negative charge:
\
_
3. Use the simulation and the reference table to fill in the table below. Assume all elements
are neutral atoms:
Element (atom)
# of Protons
# of Electrons
Nitrogen
5
2
Sulfur
Tin
35
88
2C I can calculate the mass number of an atom, the number of neutrons or protons,
given the other two values.
Directions: Reset the simulation and check the box that says stable/unstable. Create the
neutral/stable atoms shown below and fill in the table. Be sure to look at the mass number
section on the side as you are working.
Element
(stable & neutral)
# of Protons
# of
Electrons
# of
Neutrons
Mass
Number
Lithium
Beryllium
7
Fluorine
10
21
Questions:
1. Looking at the table you filled in above, how is the mass number of an atom found? Based
on what you know about the subatomic particles, explain why that is.
_
_
_
_
2. What is the mass number of an atom with 5 protons, 6 neutrons and 5 electrons? What
element is this atom?
3. Look at the last example on the table. If you have protons and a mass number, how can you
figure out the number of neutrons? Give a formula. In addition to explaining it.
_
_
_
4. How many neutrons are in a bromine atom with a mass number of 80? SHOW WORK:
5. Fill in the table below. Check your answers for the first two examples using the simulation
before moving on to the next examples:
Element
(stable & neutral)
# of Protons
# of
Electrons
# of
Neutrons
8
Mass
Number
16
Helium
3
Calcium
20
21
45
Aluminum
27
Silver
60
37
49
2D I can define isotope and write isotopic notation
Directions: Click on the symbol picture on the
bottom of the page to access the symbol feature.
The atoms will stay the same but instead of
viewing mass and charge, you are now viewing
ISOTOPIC NOTATION. Fill in the table using this
feature and then answer the questions that follow.
Element
Stable &
Neutral!
Fluorine
 Stable
 Neutral
Helium
 Stable
 Neutral
Beryllium
 Stable
 Neutral
Boron
 Stable
 Neutral
Oxygen
 Stable
 Neutral
Neon
 Stable
 Neutral
 Stable
 Neutral
# of
protons
9
# of
neutrons
10
# of
electrons
9
Mass
Number
19
Isotopic
Notation
Questions:
1. The isotopic notation includes at least three parts as shown
above in your simulation. Use the generic sample shown to
the right to write what each of the letters would represent
when written in isotopic notation
X=
Z=
A=
2. Using isotopic notation, write the symbol for an atom of argon with 22 neutrons:
3. How many neutrons are in the atom whose isotopic notation is given? 



4. Fill in the table below using the information learned in this laboratory activity:
# of
# of
# of
Isotopic
Element
Mass #
protons
neutrons
electrons
Notation
24
28
Aluminum
27
Mercury
120
48
112