Question 1

Which statement best explains why sodium (Na) and potassium (K) ions are able to be differentiated by ion channels in nerve cells?

Accepted Answer

Because Na and K ions have different sizes due to their positions on the periodic table.

Question 2

According to Mendeleev’s periodic law, what property of elements recurs periodically when elements are arranged by increasing atomic mass?

Accepted Answer

Their chemical and physical properties.

Question 3

Which quantum number describes the main energy level of an electron in an atom?

Accepted Answer

The principal quantum number $$n$$

Question 4

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

Accepted Answer

$$2n^2$$ = $$2(3)^2 = 18$

Question 5

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

Accepted Answer

Pauli exclusion principle

Question 6

For the element magnesium (Mg), which electron configuration represents its cation $$\mathrm{Mg$$^{2+}$$} in $$the ground state?

Accepted Answer

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

Question 7

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

Accepted Answer

Fluorine (F)

Question 8

What is the electron configuration for the $$\mathrm{S$$^{2-}$$}$$ ion?

Accepted Answer

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

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 increased effective nuclear charge.

Question 10

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

Accepted Answer

Rubidium (Rb)

Question 11

Why do noble gases have especially stable electron configurations?

Accepted Answer

They have completely filled s and p sublevels in their valence shell.

Question 12

Which of the following ions is largest in size?

Accepted Answer

$$\mathrm{F^-}$$

Question 13

What is the correct order of filling for the following orbitals in a multielectron atom?

Accepted Answer

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

Question 14

Which of the following statements about electron affinity is correct?

Accepted Answer

Halogens have the highest (most negative) electron affinities in their periods.

Question 15

Which quantum number is responsible for the orientation of an orbital in space?

Accepted Answer

Magnetic quantum number $$m_l$$

Question 16

A transition metal atom loses electrons to form a cation. Which electrons are removed first?

Accepted Answer

Electrons from the highest principal energy level (ns)

Question 17

Which of the following electron configurations represents an atom with all paired electrons and thus diamagnetic?

Accepted Answer

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

Question 18

Which of the following best explains the large jump in ionization energy after the removal of all valence electrons?

Accepted Answer

Core electrons are closer to the nucleus and experience a much higher effective nuclear charge.

Question 19

Which element would you expect to have the smallest atomic radius among the following: Ca, F, Si?

Accepted Answer

Fluorine (F)

Question 20

Which of the following is a correct statement about the trend in metallic character in the periodic table?

Accepted Answer

Metallic character increases down a group and decreases across a period.

Chapter 8: Periodic Properties of the Elements – Study Notes

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