Question 1

Which of the following is the correct electron configuration for a neutral atom of copper (Cu, atomic number 29)?

Accepted Answer

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

Question 2

Which statement best explains why the atomic radius decreases across a period from left to right on the periodic table?

Accepted Answer

The number of protons increases, increasing the effective nuclear charge and pulling electrons closer.

Question 3

Which of the following ions has the smallest ionic radius?

Accepted Answer

$$\mathrm{Na^+}$$

Question 4

A student draws the orbital box diagram for nitrogen (atomic number 7) as follows: $$1s\ \uparrow\downarrow\ 2s\ \uparrow\downarrow\ 2p\ \uparrow\uparrow\uparrow. $$Which rule is the student correctly applying?

Accepted Answer

Hund's Rule

Question 5

Which of the following best describes the electron configuration of a chromium atom (Cr, atomic number 24)?

Accepted Answer

$$[Ar]\ 4s^1$\ 3d^5$

Question 6

Which of the following elements has the highest first ionization energy?

Accepted Answer

Phosphorus ($$\mathrm{P})$$

Question 7

Which of the following statements about cations and anions is correct?

Accepted Answer

Cations are smaller than their parent atoms because they lose electrons.

Question 8

Which of the following correctly applies the Pauli Exclusion Principle in an orbital box diagram?

Accepted Answer

Placing two electrons with opposite spins in the same orbital.

Question 9

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

Accepted Answer

$$[Ne]\ 3s^2$\ 3p^5$

Question 10

Which of the following best explains why electronegativity increases across a period?

Accepted Answer

The effective nuclear charge increases, pulling bonding electrons closer.

Question 11

Which of the following is the correct order of filling for the first five subshells according to the Aufbau principle?

Accepted Answer

$$1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p$$

Question 12

A hospital patient receives an intravenous solution containing $$\mathrm{K^+}$$, $$\mathrm{Ca$$^{2+}$$}$$, and $$\mathrm{Cl^-}$$ ions. Which ion will have the largest ionic radius?

Accepted Answer

$$\mathrm{Cl^-}$$

Question 13

Which of the following is a correct application of Hund's Rule when filling the 2p orbitals for oxygen (atomic number 8)?

Accepted Answer

Place one electron in each 2p orbital before pairing any electrons.

Question 14

Which of the following elements would you expect to have the lowest electronegativity?

Accepted Answer

Sodium ($$\mathrm{Na})$$

Question 15

Which of the following ions is isoelectronic with neon ($$\mathrm{Ne}$$)?

Accepted Answer

$$\mathrm{Na^+}$$

Question 16

A neutral atom has the electron configuration $$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^1. $$What element is this?

Accepted Answer

Aluminum ($$\mathrm{Al})$$

Question 17

Which of the following best explains why $$\mathrm{O$$^{2-}$$} is $$larger than $$\mathrm{F^-}$$, even though both are isoelectronic?

Accepted Answer

$$\mathrm{O$$^{2-}$$}$$ has fewer protons, so the same number of electrons are held less tightly.

Question 18

Which of the following is the correct electron configuration for a $$\mathrm{Mg$$^{2+}$$}$$ ion?

Accepted Answer

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

Question 19

Which of the following best describes the trend in ionization energy as you move down a group in the periodic table?

Accepted Answer

Ionization energy decreases because the outer electrons are farther from the nucleus.

Electron Configuration and Periodic Trends: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards