Question 1

Which of the following statements 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, pulling the valence electrons closer to the nucleus.

Question 2

A neutral atom of phosphorus-31 has how many protons, neutrons, and electrons?

Accepted Answer

15 protons, 16 neutrons, 15 electrons

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 element has the electron configuration $1s^22s^22p^63s^23p^5$?

Accepted Answer

Chlorine

Question 5

What is the maximum number of electrons that can occupy the third energy level (n=3) of an atom?

Accepted Answer

$18$

Question 6

Which of the following ions is larger in size than its neutral atom?

Accepted Answer

$	ext{Cl}^-$

Question 7

A sample of lithium contains 92.41% lithium-7 (mass = 7.016 amu) and 7.59% lithium-6 (mass = 6.015 amu). What is the atomic weight of lithium? (Round to two decimal places)

Accepted Answer

$6.94\ 	ext{amu}$

Question 8

Which of the following elements is a transition metal?

Accepted Answer

Chromium

Question 9

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

Accepted Answer

$1s^22s^22p^63s^23p^63d^6$

Question 10

Which of the following best describes the Pauli Exclusion Principle?

Accepted Answer

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

Question 11

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

Accepted Answer

Fluorine

Question 12

How many orbitals are present in the 3d subshell?

Accepted Answer

$5$

Question 13

Which of the following is TRUE about noble gases?

Accepted Answer

They are generally unreactive due to their full valence shells.

Question 14

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number $(l)$

Question 15

A certain element has the abbreviated electron configuration $[Ar]4s^23d^3$. How many valence electrons does it have?

Accepted Answer

$5$

Question 16

Which of the following best explains why cations are smaller than their parent atoms?

Accepted Answer

Cations lose electrons, resulting in fewer electron shells and reduced electron-electron repulsion.

Question 17

Which of the following is the correct isotopic notation for an atom with 14 protons, 14 electrons, and 18 neutrons?

Accepted Answer

$^{32}_{14}	ext{Si}$

Question 18

Which of the following elements is most likely to form a $-2$ anion?

Accepted Answer

Oxygen

Question 19

How many electrons can occupy the $4f$ subshell?

Accepted Answer

$14$

Question 20

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 valence electrons are farther from the nucleus.

Atoms, Elements, and the Periodic Table: Structure and Properties

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