Question

1. go to the website: phet.colorado.edu. click on html5 simulations on top right of screen and choose the build an atom simulation. (http://phet.colorado.edu/en/simulation/build - an - atom)
2. explore the build an atom simulation with your group. as you explore, talk about what you find. list two things your group observed in the simulation.

a.
b.

1. click on the + sign for each of the 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?
3. play until you discover which particle(s) determine(s) the name of the element you build, and write the name of the particle here:
4. what is the name of the following atoms?

a. an atom with 3 protons and 4 neutrons:
b. an atom with 2 protons and 4 neutrons:
c. an atom with 4 protons and 4 neutrons:

1. play with the simulation to discover which particles affect the charge of an atom or ion, and explain which particles affect the charge of an atom.
2. fill in the blanks below to show your results:

a. neutral atoms have ____ protons and electrons.
b. positive ions have ____ protons than electrons.
c. negative ions have ____ protons than electrons.

1. develop a relationship (in the form of a single sentence or equation) that can predict the charge based on the number and types of particle.
2. play with the simulation to discover what affects the mass number of your atom or ion. what is a rule for determining the mass number of an atom or ion?

Explanation:

1. For question 2, observations are based on the simulation's core features: particles have distinct charges/locations, and changing particles alters atom properties.
2. Question 4: The atomic nucleus contains protons and neutrons.
3. Question 5: The number of protons (atomic number) uniquely defines an element's identity.
4. Question 6: Element names are determined by proton count (atomic number) from the periodic table.
5. Question 7: Electrons carry a negative charge; adding/removing them changes the atom's net charge, while protons/neutrons do not affect charge.
6. Question 8: Charge depends on the balance of positive protons and negative electrons.
7. Question 9: Net charge is calculated by subtracting electron count from proton count.
8. Question 10: Mass number is the total of heavy particles (protons + neutrons) in the nucleus; electrons have negligible mass.

Answer:

2.
a. Protons have a positive charge, electrons negative.
b. Neutrons have no electrical charge.

1. Protons and neutrons
2. Protons

6.
a. Lithium
b. Helium
c. Beryllium

1. Electrons affect the charge of an atom/ion. Adding electrons creates a negative charge, removing electrons creates a positive charge; protons and neutrons do not impact the net charge.

8.
a. the same number of
b. more
c. fewer

1. Net Charge = (Number of Protons) - (Number of Electrons)
2. The mass number is determined by the total number of protons and neutrons in the atom/ion (electrons have negligible mass, so they do not affect the mass number). The rule is: Mass Number = Number of Protons + Number of Neutrons