Q: What is the effective nuclear charge ($$Z_{\text{eff}}) $$experienced by a 4s electron in potassium ($$K$$), using the simple method $$Z_{\text{eff}} = Z - S$$, where $$Z is $$the atomic number and $$S is $$the number of core electrons?

$$Z_{\text{eff}} = 19 - 18 = 1$$

Q: Which property is primarily responsible for the periodic trends observed in atomic size, ionization energy, and electron affinity?

Effective nuclear charge ($$Z_{\text{eff}})$$

Question 1

Which scientist is credited with arranging the periodic table by increasing atomic number, resolving inconsistencies found when ordering by atomic mass?

Accepted Answer

Henry Moseley

Question 2

What is the effective nuclear charge ($$Z_{	ext{eff}}) $$experienced by a 4s electron in potassium ($$K$$), using the simple method $$Z_{	ext{eff}} = Z - S$$, where $$Z is $$the atomic number and $$S is $$the number of core electrons?

Accepted Answer

$$Z_{	ext{eff}} = 19 - 18 = 1$$

Question 3

Which of the following statements about atomic radius is correct?

Accepted Answer

Atomic radius decreases from left to right across a period.

Question 4

Arrange the following elements in order of increasing first ionization energy ($$IE_1$$): $$Cs$$, $$P$$, $$Zr$$, $$F.$$

Accepted Answer

$$Cs \u003c Zr \u003c P \u003c F$$

Question 5

Which group of elements has the general valence electron configuration $$ns^2np^3$?

Accepted Answer

Group 15 (V)

Question 6

Which of the following ions is isoelectronic with $$O^{2-}$$?

Accepted Answer

$$F^-$$

Question 7

Which of the following statements about ionic radii is FALSE?

Accepted Answer

$$Na^+ is $$larger than $$K^+$$

Question 8

What is the condensed electron configuration for chlorine ($$Cl$$)?

Accepted Answer

$$[Ne] 3s^2$ 3p^5$

Question 9

Which element in Group 15 would have the smallest first ionization energy ($$IE_1$$)?

Accepted Answer

Bismuth ($$Bi)$$

Question 10

Which group is most likely to form $$+1$$ ions?

Accepted Answer

Group 1 (alkali metals)

Question 11

Which of the following best describes the trend in metallic character across a period?

Accepted Answer

Metallic character decreases from left to right.

Question 12

Given the following ions: $$Na^+$$, $$Mg^{2+}$$, $$F^-$$, $$O^{2-}$$, which has the smallest ionic radius?

Accepted Answer

$$Mg^{2+}$$

Question 13

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

Accepted Answer

Cations have fewer electrons, resulting in less electron-electron repulsion and a higher $$Z_{	ext{eff}}.$$

Question 14

Which of the following elements has the largest atomic radius: $$Na$$, $$Rb$$, $$Mg$$, $$K$$?

Accepted Answer

$$Rb$$

Question 15

Which group of elements is characterized by negative electron affinities?

Accepted Answer

Group 17 (halogens)

Question 16

What is the main reason for the large jump in ionization energy after all valence electrons have been removed from an atom?

Accepted Answer

The next electron must be removed from a stable, filled shell closer to the nucleus.

Question 17

Which of the following best describes the trend in electron affinity across a period?

Accepted Answer

Electron affinity increases from left to right.

Question 18

Which of the following is the correct order of atomic radius from smallest to largest: $$Mg$$, $$Na$$, $$P$$, $$Si$$, $$Ar$$?

Accepted Answer

$$Ar \u003c P \u003c Si \u003c Mg \u003c Na$$

Question 19

Which property is primarily responsible for the periodic trends observed in atomic size, ionization energy, and electron affinity?

Accepted Answer

Effective nuclear charge ($$Z_{	ext{eff}})$$

Periodic Properties of the Elements: Structure, Trends, and Applications

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