Question 1

Which of the following statements best explains why the periodic table is currently organized by atomic number rather than atomic mass?

Accepted Answer

Atomic number reflects the number of protons, which determines the chemical properties of elements.

Question 2

Which element would have the following electron configuration: $$[Ne]3s^2$ 3p^5$?

Accepted Answer

Chlorine

Question 3

Which of the following best describes the trend in atomic radius as you move from left to right across a period in the periodic table?

Accepted Answer

Atomic radius decreases due to increasing effective nuclear charge.

Question 4

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

Accepted Answer

Cl$$^-$$

Question 5

Which group of elements is characterized by having a full valence shell and being generally unreactive?

Accepted Answer

Noble gases (Group 18)

Question 6

Which of the following best explains why the first ionization energy decreases as you move down a group?

Accepted Answer

Valence electrons are farther from the nucleus and experience more shielding.

Question 7

Which of the following elements would you expect to have the highest electron affinity?

Accepted Answer

Chlorine

Question 8

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

Accepted Answer

Metallic character decreases

Question 9

Which of the following is the correct order of increasing atomic radius for the elements Na, Mg, and Al?

Accepted Answer

Al \u003c Mg \u003c Na

Question 10

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 smaller radius.

Question 11

Which of the following reactions is a representative reaction for an alkali metal?

Accepted Answer

$$2Na(s) + Cl_2$(g) \rightarrow 2NaCl(s)$$

Question 12

Which of the following statements about effective nuclear charge ($$Z_{eff}) is $$correct?

Accepted Answer

$$Z_{eff}$$ increases across a period due to increasing nuclear charge with similar shielding.

Question 13

Which of the following best describes the electron configuration of a Cr atom?

Accepted Answer

$$[Ar]4s^1$ 3d^5$

Question 14

Which of the following elements is most likely to form a $$2+$$ cation in chemical reactions?

Accepted Answer

Magnesium

Question 15

Which of the following best explains the high first ionization energy of noble gases?

Accepted Answer

They have full valence shells, making it energetically unfavorable to remove an electron.

Question 16

Which of the following is a correct statement about the periodic trend in electron affinity?

Accepted Answer

Electron affinity generally increases (becomes more negative) across a period from left to right.

Question 17

Which of the following best describes the trend in ionic radius for anions as you move down a group?

Accepted Answer

Ionic radius increases due to the addition of electron shells.

Question 18

Which of the following is a representative reaction for a halogen?

Accepted Answer

$$H_2(g$$) + $$Cl_2(g$$) \rightarrow 2HCl(g)$$

Question 19

Which of the following best explains why the atomic radius of Li is much larger than that of He, despite Li having more protons?

Accepted Answer

The valence electron in Li is in a higher principal quantum number shell and is shielded by core electrons.

Ch8: Periodic Properties of the Elements – Structured Study Notes

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