Name: ______________________________
Period: _______________
Build an Atom
Learning Objectives:
1. Draw models that show atoms or ions.
2. Use information about the number of protons, neutrons, and electrons to
 Identify an element and its position on the periodic table
 Determine if the model is for an atom or an ion.
3. Predict how changing the number protons, neutrons, or electrons will change the element, the
charge, and the mass of an atom or ion.
Directions:
1. Go to http://phet.colorado.edu/ Search for Build an Atom. Download this to your desktop.
Explore the Build an Atom simulation.
2. Click on the three green plus signs at the right. Be sure to leave these open throughout the
simulation.
3. Using Build an Atom, experiment with the parts of atoms to find:
A. What parts go in the center of the atom? _________________________________________
B. You can call the center of the atom, the nucleus. Most atoms in our environment have a stable
nucleus which is shown on the screen. An unstable nucleus is radioactive and is shown by
wiggling.
C. Play around, and write down three examples of atoms that have a stable nucleus and include a
drawing of your nucleus.
Number of particles in
your nucleus:
1.
Protons: __
Neutrons:__
2.
Protons: __
Neutrons:__
3.
Protons: __
Neutrons:__
2/6/2016 Moore and Paul
Draw
your nucleus
http://phet.colorado.edu
What element
is it?
Page 1
D. Play until you discover which particle (or particles) determines the name of the element you
build. Which particle determines the element?
___________________________________________________________________________
E. Test your idea by identifying the element for the 3 cases.
Particles
1.
2.
3.
What
Element?
Protons: 6
Neutrons: 6
Electrons: 6
Protons: 7
Neutrons: 6
Electrons: 6
Protons: 6
Neutrons: 7
Electrons: 7
What Determines
the Element?
Proton
Neutron
Electron
Proton
Neutron
Electron
Proton
Neutron
Electron
Circle the Element
4. An ion is an atom that has a charge to it because it has an unequal number of protons and electrons.
Play until you discover what affects the charge of your atom or ion.
What is a rule for making...
A. An atom neutral (one with 0 extra charge)?
______________________________________________________________________________
B. A +ion (positive ion, one with extra positive charge)?
______________________________________________________________________________
C. A - ion (negative ion, one with extra negative charge)?
______________________________________________________________________________
5. Show a neutral atom, a positive ion, and a negative ion. (These examples should be consistent with
the rules you discovered.) All of your examples should also have a stable nucleus.
Number of Particles?
Neutral
Protons: __
Neutrons:__
Electrons:__
+ Ion
Protons: __
Neutrons:__
Electrons:__
- Ion
Protons: __
Neutrons:__
Electrons:__
2/6/2016 Moore and Paul
Draw Your
Atom or Ion
http://phet.colorado.edu
What is
the Charge?
Page 2
6. Play until you discover what affects the mass of your atom or ion.
Which particles are heavy and which particles are light?
_________________________________________________________________________________
What is a rule for determining the mass?
_________________________________________________________________________________
7. Using all of your rules, figure out what changes for each of these actions to an atom or ion. You can
test your ideas with the simulation. If you have new ideas, rewrite your rules.
Action
Add a
Proton
Action
Remove a
Neutron
Action
Remove an
Electron
Action
Add an
Electron
What
Changes?
☐Element
How Does it Change?
☐Charge
☐Mass
What
Changes?
☐Element
How Does it Change?
☐Charge
☐Mass
What
Changes?
☐Element
How Does it Change?
☐Charge
☐Mass
What
Changes?
☐Element
How Does it Change?
☐Charge
☐Mass
2/6/2016 Moore and Paul
http://phet.colorado.edu
Page 3
8. Challenges!
Design a positive ion with a charge of +2:
Particles
Protons: __
Neutrons:__
Electrons:__
Properties
Element:___
Mass:___
Charge:___
Stable Nucleus: Yes No
Design a neutral, atom with a mass of 8:
Particles
Protons: __
Neutrons:__
Electrons:__
9.
Properties
Element:___
Mass:___
Charge:___
Stable Nucleus: Yes No
Click the tab at the top that says “Game”.
A. Play each level until you make a perfect score. Call me over when you complete a level with a perfect
score and I will check it off.
Level 1 ________
2/6/2016 Moore and Paul
Level 2 ________
Level 3 ________
http://phet.colorado.edu
Level 4 ________
Page 4