Question 1

Which of the following statements best describes the periodic law as originally formulated by Mendeleev?

Accepted Answer

When the elements are arranged in order of increasing mass, certain sets of properties recur periodically.

Question 2

Which quantum number is introduced to describe the orientation of electron spin, and what values can it take?

Accepted Answer

The spin quantum number, $$m_s$$, which can be $$+\frac{1}{2} or$$ $$-\frac{1}{2}.$$

Question 3

Which of the following best explains why the 2s orbital is lower in energy than the 2p orbital in a multi-electron atom?

Accepted Answer

The 2s orbital is closer to the nucleus and experiences less shielding, resulting in greater penetration.

Question 4

Which element would you expect to have the largest atomic radius based on periodic trends?

Accepted Answer

Potassium ($$K)$$

Question 5

Which of the following ions is isoelectronic with Argon ($$Ar$$)?

Accepted Answer

$$Cl^-$$

Question 6

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

Accepted Answer

$$[Ar] 4s^2$ 3d^6$

Question 7

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

Accepted Answer

It increases due to increasing effective nuclear charge.

Question 8

Which of the following elements is expected to be the most metallic?

Accepted Answer

Rubidium ($$Rb)$$

Question 9

Which of the following ions is expected to be paramagnetic?

Accepted Answer

$$Fe^{3+}$$

Question 10

Which of the following statements about electron affinity is correct?

Accepted Answer

Electron affinity generally becomes more negative as you move to the right across a period.

Question 11

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

Accepted Answer

Cations have more protons than electrons, resulting in a greater effective nuclear charge per electron.

Question 12

Which of the following elements would you expect to have the highest second ionization energy?

Accepted Answer

Sodium ($$Na)$$

Question 13

Which of the following electron configurations corresponds to a noble gas?

Accepted Answer

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

Question 14

Which of the following best describes Hund’s Rule?

Accepted Answer

Electrons occupy degenerate orbitals singly before pairing.

Question 15

Which of the following elements is expected to have the most negative electron affinity?

Accepted Answer

Fluorine ($$F)$$

Question 16

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

Accepted Answer

Atomic radius increases due to the addition of principal energy levels.

Question 17

Which of the following is the correct electron configuration for the $$Fe^{3+}$$ ion?

Accepted Answer

$$[Ar] 3d^5$

Question 18

Which of the following elements is a metalloid and can exhibit both metallic and nonmetallic behavior in chemical reactions?

Accepted Answer

Silicon ($$Si)$$

Question 19

Which of the following best describes the trend in metallic character as you move from left to right across a period?

Accepted Answer

Metallic character decreases.

Question 20

Which of the following best explains why halogens tend to form $$1^-$$ anions in reactions with metals?

Accepted Answer

Halogens have one fewer electron than the next noble gas and gain one electron to achieve a stable configuration.

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

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