Question 1

Which of the following statements best describes the difference between atomic number ($$Z) $$and mass number ($$A$$)?

Accepted Answer

$$Z is $$the number of protons, while $$A is $$the sum of protons and neutrons in the nucleus.

Question 2

A neutral atom of carbon has an atomic number $$Z = 6$$ and a mass number $$A = 14. $$Which of the following statements is correct about this atom?

Accepted Answer

It has 6 protons, 8 neutrons, and 6 electrons.

Question 3

Which of the following electron configurations correctly represents the ground state of a neutral nitrogen atom ($$Z = 7$$)?

Accepted Answer

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

Question 4

Which principle explains why electrons fill each degenerate orbital singly before pairing up in the same orbital?

Accepted Answer

Hund's Rule

Question 5

Which of the following is an isotope of $$^{12}C$$?

Accepted Answer

$$^{14}C$$

Question 6

A neutral atom has 17 protons, 18 neutrons, and 17 electrons. What is its atomic number and mass number?

Accepted Answer

Atomic number $$= 17$$, Mass number $$= 35$$

Question 7

Which of the following statements about the Pauli Exclusion Principle is correct?

Accepted Answer

No two electrons in the same atom can have the same set of four quantum numbers.

Question 8

Which electron configuration violates the Aufbau Principle?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^6$$\ $$3d^2$$\ $$4s^2$$

Question 9

Which of the following best explains why isotopes of the same element have nearly identical chemical properties?

Accepted Answer

They have the same number of electrons and identical electron configurations.

Question 10

A hospital uses $$^{99m}Tc ($$technetium-99m) as a radioactive tracer. If $$^{99m}Tc$$ has 43 protons, how many neutrons does it have?

Accepted Answer

56

Question 11

Which of the following electron configurations represents an atom that violates Hund's Rule?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^2$$\ (with both 2p electrons paired in the same orbital)

Question 12

Which of the following best describes the electron configuration for a sodium ion ($$Na^+$$)?

Accepted Answer

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

Question 13

Which of the following is true for all isotopes of an element?

Accepted Answer

They have the same number of protons.

Question 14

Which of the following best explains why the electron configuration of oxygen is $$1s^2$$\ $$2s^2$$\ $$2p^4$$?

Accepted Answer

Oxygen has 8 electrons, which fill the $$1s$$, $$2s$$, and $$2p$$ orbitals according to the Aufbau Principle.

Question 15

A neutral atom of element X has an atomic number of 20 and a mass number of 40. Which of the following is correct?

Accepted Answer

It has 20 protons, 20 neutrons, and 20 electrons.

Question 16

Which of the following is the correct order of filling for the first four energy sublevels according to the Aufbau Principle?

Accepted Answer

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

Question 17

A patient is exposed to a radioactive isotope with 53 protons and 74 neutrons. What is the isotope's mass number?

Accepted Answer

127

Question 18

Which of the following best describes the relationship between atomic structure and chemical bonding in organic molecules?

Accepted Answer

The arrangement of electrons in atomic orbitals determines how atoms bond and interact in molecules.

Question 19

Which of the following is NOT a rule used to determine electron configuration?

Accepted Answer

Heisenberg Uncertainty Principle

Question 20

A neutral atom of fluorine has the electron configuration $$1s^2$$\ $$2s^2$$\ $$2p^5. $$How many unpaired electrons does it have?

Accepted Answer

1

Atomic Structure and Electron Configuration: Organic Chemistry Foundations

Study Guide - Practice Questions