Question 1

Which of the following statements best explains why Mendeleev is credited with the development of the periodic table, even though Lothar Meyer reached similar conclusions?

Accepted Answer

Mendeleev predicted the existence and properties of undiscovered elements, using chemical properties to organize the table.

Question 2

Which equation is used to estimate the effective nuclear charge ($$Z_{	ext{eff}}) $$experienced by a valence electron in a multi-electron atom?

Accepted Answer

$$Z_{	ext{eff}} = Z - S$$

Question 3

Which trend is observed for atomic radius as you move from left to right across a period in the periodic table?

Accepted Answer

Atomic radius decreases due to increased effective nuclear charge.

Question 4

Which of the following ions is the smallest in the isoelectronic series: $$\mathrm{O$$^{2-}$$}$$, $$\mathrm{F^-}$$, $$\mathrm{Na^+}$$, $$\mathrm{Mg$$^{2+}$$}$$?

Accepted Answer

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

Question 5

Which of the following best describes the general trend in first ionization energy ($$I_1) $$across a period?

Accepted Answer

$$I_1$$ increases from left to right due to increasing effective nuclear charge.

Question 6

Which of the following elements would you expect to have the most exothermic (most negative) electron affinity?

Accepted Answer

Fluorine ($$\mathrm{F})$$

Question 7

A sodium atom ($$\mathrm{Na}) $$loses one electron to form $$\mathrm{Na^+}. $$Which statement correctly describes the change in size?

Accepted Answer

$$\mathrm{Na^+} is $$smaller than $$\mathrm{Na}$$ because it has fewer electrons and less electron-electron repulsion.

Question 8

Which of the following best explains why the noble gases have very low chemical reactivity?

Accepted Answer

They have completely filled valence shells, resulting in high ionization energies and positive electron affinities.

Question 9

Which of the following oxides would you expect to be basic?

Accepted Answer

$$\mathrm{Na_2O}$$

Question 10

Which property is characteristic of metalloids and makes them useful in the electronics industry?

Accepted Answer

They are electrical semiconductors.

Question 11

Which of the following best explains why the alkali metals are not found in their elemental form in nature?

Accepted Answer

They are highly reactive due to their low ionization energies.

Question 12

Which of the following reactions represents the formation of a superoxide by an alkali metal?

Accepted Answer

$$\mathrm{K} + \mathrm{O}_2 \rightarrow \mathrm{KO}_2$$

Question 13

Which of the following statements about the electron configuration of ions is correct?

Accepted Answer

Cations lose electrons from the highest principal quantum number ($$n) $$first.

Question 14

Which group of elements is characterized by having the highest first ionization energies in the periodic table?

Accepted Answer

Noble gases (Group 8A)

Question 15

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

Accepted Answer

Metallic character increases because ionization energy decreases.

Question 16

Which of the following best describes the difference in chemical behavior between oxygen and polonium in Group 6A?

Accepted Answer

Oxygen is more likely to form a $$2-$$ anion, while polonium is more likely to form a positive ion.

Question 17

Which of the following best explains the large jump in ionization energy observed after all valence electrons have been removed from an atom?

Accepted Answer

The next electron is removed from a core level, which is much closer to the nucleus and more tightly bound.

Question 18

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

Accepted Answer

Electron affinity becomes more negative across a period, with exceptions for full and half-filled subshells.

Question 19

Which of the following is a property of nonmetal oxides?

Accepted Answer

They are acidic and form molecular compounds.

Question 20

A sample of an unknown element is a dull, brittle solid that is a poor conductor of electricity. Which of the following is the most likely classification for this element?

Accepted Answer

Nonmetal

Chapter 7: Periodic Properties of the Elements – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard