Question 1

Which of the following best explains why helium is chemically inert while hydrogen is highly reactive?

Accepted Answer

Helium has a filled outermost shell with two electrons, resulting in a stable electron configuration.

Question 2

According to the quantum-mechanical model, what does an orbital represent?

Accepted Answer

A probability map showing where an electron is likely to be found.

Question 3

Which of the following electron configurations represents a ground-state carbon atom?

Accepted Answer

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

Question 4

Which principle states that no more than two electrons can occupy the same orbital, and they must have opposite spins?

Accepted Answer

Pauli exclusion principle

Question 5

What is the electron configuration for a sodium atom (Na, atomic number 11) using noble gas core notation?

Accepted Answer

$$[Ne]\ 3s^1$

Question 6

Which of the following statements about periodic trends is correct?

Accepted Answer

Atomic size decreases across a period and increases down a group.

Question 7

A neutral atom of silicon (Si) has 14 electrons. How many valence electrons does it have?

Accepted Answer

4

Question 8

Which of the following best describes Hund’s rule?

Accepted Answer

Electrons fill orbitals of equal energy singly before pairing.

Question 9

Which element is most likely to form a $$+1$$ cation to achieve a noble gas configuration?

Accepted Answer

Sodium (Na)

Question 10

Which of the following is true about the energy ordering of orbitals in multi-electron atoms?

Accepted Answer

The $$4s$$ subshell is lower in energy than the $$3d$$ subshell.

Question 11

Which of the following elements has the highest ionization energy?

Accepted Answer

Neon (Ne)

Question 12

What is the shape of a $$p$$ orbital?

Accepted Answer

Dumbbell-shaped

Question 13

Which block of the periodic table contains the transition metals?

Accepted Answer

d block

Question 14

Which of the following best explains why atomic size increases as you move down a group?

Accepted Answer

The principal quantum number $$n$$ increases, so electrons are farther from the nucleus.

Question 15

Which of the following is the correct electron configuration for chlorine (Cl, atomic number 17)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^5$$

Question 16

Which of the following statements about metallic character is correct?

Accepted Answer

Metallic character increases as you move down a group.

Question 17

A student claims that the Bohr model can predict the emission spectra of all elements. Is this correct?

Accepted Answer

No, the Bohr model only accurately predicts the emission spectrum of hydrogen.

Question 18

Which of the following elements is most likely to gain one electron to achieve a noble gas configuration?

Accepted Answer

Chlorine (Cl)

Question 19

Which quantum number specifies the principal shell of an orbital?

Accepted Answer

$$n$$

Question 20

Which of the following best describes the relationship between wavelength and frequency for light?

Accepted Answer

They are inversely proportional.

Electrons in Atoms and the Periodic Table: Chapter 9 Study Guide

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