# Element Builder Gizmo Answer Key

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Gizmos refer to the interactive math and science virtual labs and simulations that are designed for grades 3-12. They bring powerful new interactive STEM learning experiences to the classrooms.

There are a lot of courses in Gizmos. One of them is called Global Infectious Diseases and Social Justice: Lessons from Science, History, & Humanities. In the exam of this course, there is something called Student Exploration: Element Builder. For those who are going to take the exam, you may want to check out the answer key of Element Builder Gizmo below. Take a note that the correct answers are in bold.

Prior Knowledge Questions

1. What are some of the different substances that make up a pizza? Sauce, cheeses, vegetables and pepperoni
2. What substances make up water? Two hydrogen and oxygen
3. What substances make up an iron pot? Hydrogen and Oxygen 3

Gizmo Warm-up

1. Use the arrow buttons to add protons, neutrons, and electrons to the atom. Press Play.
A. Which particles are located in the nucleus? Protons and neutrons
B. Which particles orbit around the nucleus? Electrons
2. Turn on Show element name. What causes the element name to change? Adding or subtracting protons and neutrons.

Activity A: Subatomic particles

Question: What are the properties of protons, neutrons, and electrons?

1. Observe: Turn on Show element symbol and Element notation. Three numbers surround the element symbol: the mass number (a) electrical charge (no number is displayed if the atom is neutral) and the atomic number (Z).
2. Investigate: What how the numbers change as you add or remove particles.
A. Which number is equal to the number of protons in the atom? Atomic number
B. How can you calculate the number of neutrons (N) in an atom? You subtract the atomic m ass by the amount of protons.
C. Which particle (proton, neutron, or electron) has a positive charge? Proton
Negative change? Neutron                                        No change at all? Electron
3. Analyze: An isotope is an alternative form of an element. Each isotope of an element has the same number of protons, but a different number of neutrons. The isotope is represented by the atomic symbol and mass number, such as He-4. Some isotopes are stables, while others are radioactive, which means the atoms decay over time and emit radiation.
A. What are the stable isotopes of carbon? C-6
B. What are the stable isotopes of nitrogen? N-7
C. List two radioactive isotopes of oxygen: O-8
4. Practice: Use the Gizmo to answer the following questions.
A. How many electrons are in a neutral atom of lithium? 3
B. How many neutrons are in an atom of Mg-25? 13
C. What is the mass number of an atom with 5 protons and 7 neutrons? 12
D. When at atom is charged, it is called an ion. How many electrons are in O2? 1.6
E. How many electrons are in Mg2+?

Activity B: Electron configurations

Question: How are electrons arranged around the nucleus of an atom?

1. Observe: Add electrons to your atom until you have used all the available electrons. How are the electrons arranged?
2. Analyze: Electrons are arranged in orbits called energy levels, shown in the Gizmo.
A. How many electrons can fit in the first energy level?
B. How many electrons can fit in the second energy level?
C. How many electrons can fit in the third energy level?
3. Observe: Click Reset. The electrons in the outermost orbit, called valence electrons, help to create chemical bonds. Create a lithium atom (3 protons, 4 neutrons, 3 electrons). How many valence electrons are in a neutral lithium atom?
4. Diagram: Turn on Show electron dot diagram. The valence electrons of an atom are shown in an electron dot diagram. Each dot represents a valence electron. Draw the electron dot diagram for neutral lithium:
5. Practice: Turn off Show electron dot diagram. Use the Gizmo to create a neutral atom of each of the following elements. Draw an electron dot diagram for each. When you are finished, turn on Show electron dot diagram and check your answers.

H            He          Li            Be          B             C             N

O            F             Ne          Na          Mg         Al            Si

1. Extend your thinking: Many properties are determined by the number of valence electrons. Which element probably has similar properties to lithium? Beryllium?

Explain:

Extension: The periodic table

Question: The 117 or so known elements are arranged in the periodic table. Why does the periodic table have the shape it has?

1. Form a hypothesis: Look at the first three rows of the periodic table below.

Why do you think the elements are arranged the way that they are?

1. Draw diagrams: Create an electron dot diagram for each of the elements below. Use the Gizmo to help you do this. To check your work, turn on Show electron dot diagram.

H                                                                                                      He

Li            Be          B             C             N            O            F             Ne

Na          Mg         Al            Si            P             S             Cl            Ar

1. Analyze: What do the elements in each column of the periodic table have in common?
2. Draw conclusions: How is the periodic table organized?