GIZMOS - Periodic Trends Answer Key - Already Graded (Score- A) Guaranteed A+ Score: Updated

Student Exploration: Periodic Trends

Directions: Follow the instructions to go through the simulation. Respond to the questions and

prompts in the orange boxes.

Vocabulary: atomic radius, electron affinity, electron cloud, energy level, group, ion, ionization energy, metal,

nonmetal, nucleus, period, periodic trends, picometer, valence electron

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

1. On the image at right, the two magnets are the same. Which paper

clip would be harder to remove?

2. Which magnet would be most likely to attract additional paper clips?

3. What is the relationship between the thickness of the book and the ability of the magnet to hold on to and

attract paper clips?

Gizmo Warm-up

Just as the thickness of a book changes how strongly a magnet attracts a paper clip, the

size of an atom determines how strongly the nucleus attracts electrons. In the Periodic

Trends Gizmo, you will explore this relationship and how it affects the properties of

different elements.

The atomic radius is a measure of the size of the electron cloud, or the region where

electrons can be found. To begin, check that H (hydrogen) is selected in Group 1 on the left. Turn on Show

ruler. To measure the radius, drag one end of the ruler to the proton in the nucleus and the other end to the

electron. Click Save radius to record the value.

Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

b

b

the thicker the book The ability of the magnet to hold onto and attract paper clips decreases

1. What is the radius of hydrogen? 53 p.m.

Notice that the radius is measured in picometers (pm). A picometer is one

trillionth of a meter.

2. On the right side of the Gizmo, select Li. Connect the right side of the ruler to

the outermost electron, or valence electron. What is the radius of lithium?

167 p.m.

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?

2. Collect data: Use the ruler to measure the atomic radii of the group 1 elements. As you do so, count the

energy levels (shown as rings of electrons) in each atom. Record in the table.

3. Observe: What happens to the radius as you move down group 1?

4. 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?

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

6. Predict: How do you think the radius of an atom will change as you move across a period (horizontal row)

in the periodic table?

7. Collect data: Beginning with Na, record the number of energy levels, number of protons, and atomic radius

for each element in period 3.

Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

Activity A:

Atomic radius

Get the Gizmo ready:

● Check that Atomic radius is selected from the

drop-down menu.

it would get larger

Element H Li Na K Rb Cs

Number of energy

levels

1 2 3 4 5 6

Ato

mic radius (pm)

53pm 167 pm. 190 p.m. 243pm 265pm 290pm

it increases

the radii keeps increasing as you go down the groups

the more energy levels there are, the greater the radius of the atom is

I think it will decrease

Element Na Mg Al Si P S Cl 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) 190p

m 144p

m

118p

m

111p

m

98pm 88pm 79pm 71pm

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