Question 1

Which of the following best explains why aluminum (Al) has a lower density than iron (Fe) and platinum (Pt)?

Accepted Answer

Aluminum atoms have a larger atomic radius and lower atomic mass, resulting in fewer atoms per unit volume.

Question 2

According to the periodic law, when elements are arranged in order of increasing atomic number, which of the following properties recur periodically?

Accepted Answer

Chemical and physical properties

Question 3

Which scientist is credited with arranging the periodic table by increasing atomic number, resolving inconsistencies such as the placement of Te and I?

Accepted Answer

Moseley

Question 4

What is the condensed electron configuration for sodium (Na)?

Accepted Answer

$$[Ne]3s^1$

Question 5

Which principle states that no two electrons in an atom can have the same four quantum numbers?

Accepted Answer

Pauli Exclusion Principle

Question 6

Which of the following ions is isoelectronic with Ne?

Accepted Answer

$$\mathrm{F^-}$$

Question 7

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

Accepted Answer

Neon (Ne)

Question 8

Why are cations smaller than their parent atoms?

Accepted Answer

Cations have fewer electrons, reducing electron-electron repulsion and resulting in a smaller radius.

Question 9

Which of the following best describes the trend in atomic radius across a period from left to right?

Accepted Answer

Atomic radius decreases due to increasing effective nuclear charge.

Question 10

Which element would you expect to have the most metallic character?

Accepted Answer

Cesium (Cs)

Question 11

Which of the following ions is expected to be diamagnetic?

Accepted Answer

$$\mathrm{Zn$$^{2+}$$}$$

Question 12

Which of the following statements about electron affinity is correct?

Accepted Answer

Electron affinity is the energy change when an electron is added to a gaseous atom.

Question 13

Which of the following elements has the electron configuration $$[Ar]4s^2$ 3d$$^{10}$$ 4p^1$?

Accepted Answer

Gallium (Ga)

Question 14

Which rule states that the lowest energy is attained when the number of electrons with the same spin is maximized in degenerate orbitals?

Accepted Answer

Hund's Rule

Question 15

Which of the following best explains why the atomic radius increases as you move down a group in the periodic table?

Accepted Answer

Additional principal energy levels are added, increasing the distance of valence electrons from the nucleus.

Question 16

Which of the following elements is most likely to form a $$2+$$ cation to achieve a noble gas configuration?

Accepted Answer

Magnesium (Mg)

Question 17

Which of the following is the correct order of filling for the sublevels according to the Aufbau principle?

Accepted Answer

$$1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p \rightarrow 4s \rightarrow 3d$$

Question 18

Which of the following best describes the trend in first ionization energy across a period from left to right?

Accepted Answer

First ionization energy increases due to increasing effective nuclear charge.

Question 19

Which of the following elements is a metalloid and often used as a semiconductor?

Accepted Answer

Silicon (Si)

Question 20

Which of the following ions is largest in size?

Accepted Answer

$$\mathrm{S$$^{2-}$$}$$

Periodic Properties of the Elements: Structure, Electron Configuration, and Trends

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