Periodic Trends Gizmo Answer Key

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Gizmo is an online learning platform. It will allow you to learn science and math. Periodic Trends is one of the subjects that you will learn on Gizmo. If you want to take Periodic Trends test on Gizmo and need the answer to pass that test, now you are able to find out through this article.

Periodic Trends Gizmo Answers

Activity A: Atomic Radius

Question: What factors affect the radius of an atom?

  1. Predict: How do you think the radius of an atom will change as you move down a group (Vertical column) in the periodic table?

Answer: It will get bigger

  1. Collect data: Use the ruler to measure the atomic radii of the group 1 elements. As you do so, count the energy levels in each atom. Record in the table
Element H Li Na K Rb Cs
Number of energy levels 1 2 3 4 5 6
Atomic radius (pm) 53 167 190 243 265 298
  1. Observe: What happens to the radius as you move down group 1?

Answer: It increases

  1. Explore: Turn off Show ruler. Select Li, and then select Be. Observe the radii of the elements in group 2. Then look at other groups. What pattern do you see?

Answer: The radius grows as you move down

  1. Draw a conclusion. In general, what is the effect of the number of energy levels on the radius of an atom?

Answer: When the energy levels increase, the radius increases

  1. Predict: How do you think the radius of an atom will change as you move across a period in the periodic table?

Answer: It will decrease

  1. Collect Data: Beginning with Na, record the number of energy levels, number of protons, and atomic radius for each element in period 3.
Element Na Mg AI Si P S CI Ar
Number of energy levels 3 3 3 3 3 3 3 3
Number of protons 11 12 13 14 15 16 17 18
Atomic radius (pm) 190 145 118 111 98 88 79 71
  1. Observe: What happens to the radius as you move across a period?

Answer: It decreases

  1. Explore: Investigate other periods in the periodic table. Does the same trend occur? Hypothesize why this trend occurs.

Answer: Yes. Each period, the number of protons increases and the energy levels stay the same.

  1. Analyze: Consider how the number of protons might affect the size of the electron cloud.

A. As you move across a period, are new energy levels added?

Answer: No

B. What happens to the number of protons in the nucleus as you move from one element to the next across a period?

Answer: It increases

C. If the proton number increases while the number of energy levels remain constant, what happens to the attractive force between the nucleus and the electrons?

Answer: It grows

D. How does your answer to the previous question explain the trend in radii across a period?

Answer: It grows across a period, but the energy levels stay the same. So, the electrons are pulled in tighter.

  1. Extend your thinking. The Gizmo enables you to examine ions or atoms that have gained or lost electrons. Select Na and turn on Show ion. Compare the radius of the neutral atom to that of the ion. Repeat with CI. Then look at other ions. See if you can find a pattern.

A. Why do you think the NA+ ion is smaller than a neutral Na Atom?

Answer: There are less electrons, so less energy levels or orbitals.

B. Why do you think the CI ion is larger than a neutral CI atom?

Answer: There are more electrons, which means more orbitals.

Activity B: Removing and Adding Electrons

Questions: How does the radius of an atom affect the ability of the protons in the nucleus to hold on to and attract electrons?

  1. Predict: Ionization energy (IE) is the energy required to remove an electron from an atom. As atomic radius increases, the valence electrons get farther from the nucleus. How do you think an atom’s size will affect its ability to hold on to its valence electrons? Why?

Answer: The bigger the atom, the more orbitals it will have to hold electrons.

  1. Investigate: Select H. In the Gizmo, the hydrogen atom is shown next to a positive charge. As you move the atom to the right, the force of attraction between the positive charge and the valence electron will increase until the electron is removed. Slowly drag the atom towards the charge. After the electron is removed, use the ruler to measure the distance between the original and the final position of the electron. Record the distance and ionization energy in the table, then repeat for the other group 1 elements.
Element H Li Na K Rb Cs Fr
Distance 268 392 397 414 417 423 422
Ionization energy 1312 520 496 419 403 376 380
  1. Analyze: What trend do you notice?

Answer: Ionization means it will decrease down a group

  1. Investigate: Collect data for ionization energy across a period. Record in the table below.
Element Na Mg AI Si P S CI Ar
Distance 397 345 379 335 286 289 235 177
Ionization 496 738 578 787 1012 1000 1251 1521
  1. Analyze: What trend do you notice?

Answer: It increases across the period

  1. Explore: Examine other groups and periods in the periodic table to see if the same trends exist. What trends do you see in ionization energy down a group and across a period?

Answer: It decreases down a group

  1. Think and discuss: As you move down a group, you will recall that the radius increases. Why do you think an increase in atomic radius would result in a lower ionization energy?

Answer: The amount of energy needed to remove electrons decreases as the distance between the nucleus and electrons increases.

  1. Think and discuss: As you move across a period, you will recall that the radius decreases. Why do you think a decrease in atomic radius would result in a greater ionization energy?

Answer: The opposite of above

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