Question 1

Which of the following is the correct full electron configuration for oxygen (O)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^4$$

Question 2

For an electron in the 2p subshell of oxygen, which of the following is a possible set of quantum numbers $$(n,\ l,\ m_l,\ m_s)$$?

Accepted Answer

$$(2,\ 1,\ 0,\ +\frac{1}{2})$$

Question 3

Which of the following is the condensed electron configuration for rubidium (Rb)?

Accepted Answer

$$[Kr]\ 5s^1$

Question 4

Which of the following is the correct condensed electron configuration for sulfur (S)?

Accepted Answer

$$[Ne]\ 3s^2$\ 3p^4$

Question 5

Which of the following is the correct condensed electron configuration for copper (Cu)?

Accepted Answer

$$[Ar]\ 4s^1$\ 3d$$^{10}$$

Question 6

Refer to the periodic table image. Which group (A, B, C, or D) contains elements with two unpaired p electrons in their valence shell?

Accepted Answer

Group C

Question 7

Why do elements in group C of the periodic table have two unpaired p electrons in their valence shell?

Accepted Answer

They have four electrons in the p subshell, filling two orbitals with single electrons and one with a pair.

Question 8

Which orbital-filling diagram violates the Pauli exclusion principle?

Accepted Answer

A diagram where two electrons in the same orbital have the same spin.

Question 9

Explain why the Pauli exclusion principle is violated in the orbital-filling diagram you identified.

Accepted Answer

Because no two electrons in the same orbital can have the same set of quantum numbers, including spin.

Question 10

Given the atomic radii in the image (215 pm, 114 pm, 197 pm), which sphere represents bromine (Br)?

Accepted Answer

The sphere with $$r = 114\ \mathrm{pm}$$

Question 11

Which sphere in the image represents strontium (Sr), and why?

Accepted Answer

The sphere with $$r = 215\ \mathrm{pm}$$, because strontium is an alkaline earth metal with a larger atomic radius.

Question 12

Which sphere in the image represents calcium (Ca), and why?

Accepted Answer

The sphere with $$r = 197\ \mathrm{pm}$$, because calcium is smaller than strontium but larger than bromine.

Question 13

Which of the following best explains why atomic radius increases down a group in the periodic table?

Accepted Answer

Additional electron shells are added, increasing the distance between the nucleus and the outermost electrons.

Question 14

Which of the following elements would you expect to have the highest first ionization energy?

Accepted Answer

Bromine (Br)

Question 15

Which of the following statements about electron configurations is correct?

Accepted Answer

Copper (Cu) has a filled $$3d$$ subshell and a single electron in the $$4s$$ subshell.

Question 16

Which of the following best describes Hund's rule?

Accepted Answer

Electrons occupy degenerate orbitals singly before pairing.

Question 17

A neutral atom of sulfur has how many unpaired electrons in its ground state?

Accepted Answer

2

Question 18

Which of the following quantum numbers describes the orientation of an orbital in space?

Accepted Answer

$$m_l$$

Chapter 2 Practice: Electron Configurations, Quantum Numbers, and Periodic Trends

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