Name: ______________________________________ Date: ________________________

Student Exploration: Electron Configuration

Vocabulary: atomic number, atomic radius, Aufbau principle, chemical family, diagonal rule, electron configuration, Hund’s rule, orbital, Pauli exclusion principle, period, shell, spin, subshell

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

1. Elvis Perkins, a rather shy fellow, is getting on the bus shown at right. Which seat do you think he will probably sit in? Mark this seat with an “E.”

2. Marta Warren gets on the bus after Elvis. She is tired after a long day at work. Where do you think she will sit? Mark this seat with an “M.”

3. In your experience, do strangers getting on a bus like to
Sodium electron configuration: 1s22s22p63s1 Atomic radius: 190 pm

3. Compare: Click Next element, and then add an electron to the magnesium atom. Click check, and record the electron configuration and atomic radius below.

Magnesium electron configuration: 1s22s22p63s13s2 Atomic radius: 145 pm

4. Gather data: Create electron configurations for the next six elements. Record the electron configuration and atomic radius of each. (Note: The symbol for picometer is pm.)

Element
Number of electrons
Electron
configuration
Atomic radius (pm)
Aluminum
13
1s22s22p63s13s23p1
118
Silicon
14
1s22s22p63s23p2
111
Phosphorus
15
1s22s22p63s23p3
98
Sulfur
16
1s22s22p63s23p4
88
Chlorine
17
1s22s22p63s23p5
79
Argon
18
1s22s22p63s23p6
71

5. Analyze: How does the atomic radius change across a period of the periodic table?

The atomic radius decreases across a period of the periodic table.

(Activity B continued on next page)Activity B (continued from previous page)

6. Interpret: Select the ATOMIC RADIUS tab. What do you notice? As atomic number increases there is a decrease in atomic radius.

7. Predict: On the ATOMIC RADIUS tab click Clear. Select the PERIODIC TABLE tab. Elements in the same column of the periodic table are called chemical families, or groups.

How do you think the size of atoms will change from top to bottom within a chemical family?

As you travel down the periodic table, you add new electron shells that