Name:______Date: ______

BUILD AN ATOM

Learning Goals: You will be able to:

1. Make atom models that show stable atoms or ions.

2. Use given information about subatomic particles to

 Identify an element and its position on the periodic table

 Draw models of atoms

 Determine if the model is for a neutral atom or an ion.

3. Predict how addition or subtraction of a proton, neutron, or electron will change the element, the charge, and the mass of an atom or ion.

Procedure:

  1. Direct your browser to the PHET Build-an-atom simulation at:

-Make sure the four choices on the right of the screen (Element, Symbol, Mass Number, Charge) are all expanded. The green + box will expand the selection, and the red – box will collapse the section.

-Under “Model”, select the radio button that says “orbits”.

-Make sure the 3 choices at the bottom (Show element name, Show neutral/ion, Show stable/unstable) are all checked.

-Note that at any time you can click the “Reset All” button in the bottom right corner.

  1. Explore the simulation.

-Which particles are you able to drag into the center? ______

-What is the center called? ______

  1. Notice that as you build your atom, the name of the element will appear in the center, and the element symbol will be highlighted on the “element” section in the top right.

-What determines the name of the element you build? ______

  1. Notice that as you build your atom, the word “stable” or “unstable” will appear in the center.

-Identify 1 example of a stable atom and 1 example of an unstable atom in the table:

How many protons are in your atom? / How many neutrons are in your atom / What is the name of the element you built?
STABLE
UNSTABLE

-What seems to be a good rule to make the center of the atom stable? ______

______

  1. Notice that as you build your atom, you will see a red “+ Ion”, black “Neutral Atom” or blue “-Ion” appear in the top right. The charge is also indicated in the “net charge” section in the bottom right. The mass of the atom is indicated in the “Mass number” section on the right.In the table below, check the columns that would change as a result of adding or removing the stated particle.

Name of Element / Charge / Mass
Adding/removing proton
Adding/removing neutron
Adding/removing electron

-What is a rule for making an atom with no charge (a neutral atom)?

______

-What is a rule for making an atom with a positive charge (a positive ion)?

______

-What is a rule for making an atom with a negative charge (a negative ion)?

______

-Identify 1 example each of a neutral atom, positive ion and negative ion in the table:

What is in your atom/ion? / Draw your atom/ion / What is the charge?
NEUTRAL ATOM / # protons:
# neutrons:
# electrons:
POSITIVE ION / # protons:
# neutrons:
# electrons:
NEGATIVE ION / # protons:
# neutrons:
# electrons:

-What is a rule for determining mass? ______

  1. Design a positive ion with a charge of +2 Design a neutral stable atom with a mass

and draw your atom in the box. of 9 and draw your atom in the box.

  1. What can you make with 4 protons and 4 neutrons? ______

A. Oxygen atomD. Beryllium atom

B. Oxygen ion E. Beryllium ion

C. Choices A & B F. Choices D & E

  1. If you have 5 protons and 6 neutrons, how many electrons would you have to add to make a neutral atom? ______
  2. What is the mass of an atom with 8 protons 9 neutrons and 8 electrons? ______
  3. If you have 5 protons, 6 neutrons, & 5 electrons, what would the element symbol look like?
  1. If you have 8 protons, 9 neutrons, 10 electrons, what would the charge be? ______

A. Zero, it’s an atom

B. +2 ion

C. +1 ion

D. -1 ion

E. -2 ion

When you are finished, click on the GAME tab at the top left of the screen and see what you have learned!