Question 1

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number ($$l)$$

Question 2

For a hydrogen atom, which of the following statements about the energy of its orbitals is correct?

Accepted Answer

All orbitals with the same principal quantum number ($$n) $$are degenerate and have the same energy.

Question 3

Which set of quantum numbers is NOT allowed for an electron in an atom?

Accepted Answer

$$n = 2$$, $$l = 2$$, $$m_l = 1$$, $$m_s = +\frac{1}{2}$$

Question 4

Which orbital type is characterized by being spherical in shape?

Accepted Answer

s orbital

Question 5

According to the Pauli Exclusion Principle, how many electrons can occupy the same orbital?

Accepted Answer

Two, with opposite spins

Question 6

Which of the following electron configurations represents a halogen in its ground state?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^5$$

Question 7

Which element has the electron configuration $$[Ar] 4s^1$ 3d^5$?

Accepted Answer

Chromium (Cr)

Question 8

What is the maximum number of electrons that can occupy the $$3d$$ subshell?

Accepted Answer

10

Question 9

Which quantum number describes the orientation of an orbital in space?

Accepted Answer

Magnetic quantum number ($$m_l)$$

Question 10

Which of the following ions is largest in size?

Accepted Answer

$$F^-$$

Question 11

What is the electron configuration for $$Fe^{2+}$$?

Accepted Answer

$$[Ar] 3d^6$

Question 12

Which of the following statements about ionization energy is correct?

Accepted Answer

Ionization energy increases across a period.

Question 13

Which of the following elements is most likely to form a cation?

Accepted Answer

Sodium

Question 14

In an isoelectronic series with 10 electrons, which ion has the smallest radius?

Accepted Answer

$$Na^+$$

Question 15

Which of the following best explains why the atomic radius decreases across a period?

Accepted Answer

The nuclear charge increases, pulling electrons closer.

Question 16

Which of the following is the correct condensed electron configuration for potassium (K)?

Accepted Answer

$$[Ar] 4s^1$

Question 17

Which of the following statements about electron affinity is true?

Accepted Answer

Electron affinity is typically negative and generally increases across a period.

Question 18

Which element is filling its $$4f$$ sublevel in the periodic table?

Accepted Answer

Cerium (Ce)

Question 19

If an atom has the electron configuration $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$ $$3d^{10}$$ $$4p^5$$, what is the element?

Accepted Answer

Bromine (Br)

Question 20

Which of the following best describes the filling order of orbitals in transition metals?

Accepted Answer

The $$4s$$ orbitals fill before the $$3d$$ orbitals.

Electronic Structure of Atoms: Quantum Numbers, Orbitals, and Electron Configurations

Study Guide - Practice Questions