Question 1

Which of the following best explains why atomic radius decreases across a period from left to right in the periodic table?

Accepted Answer

The nuclear charge increases while the number of electron shells remains the same, pulling electrons closer to the nucleus.

Question 2

Which element would have the highest first ionization energy among the following: Na, Mg, Al, Si?

Accepted Answer

Si

Question 3

Which of the following statements about Group 1 (alkali metals) is correct?

Accepted Answer

They all have the same number of valence electrons and similar chemical reactivity patterns.

Question 4

Which of the following reactions correctly represents the reaction of a Group 1 metal with water?

Accepted Answer

$$2\mathrm{Na}(s) + 2\mathrm{H}_2\mathrm{O}(l) \rightarrow 2\mathrm{NaOH}(aq) + \mathrm{H}_2(g)$$

Question 5

Which of the following best describes the trend in electronegativity as you move down a group in the periodic table?

Accepted Answer

Electronegativity decreases due to increased atomic radius and shielding effect.

Question 6

Which of the following oxides is amphoteric and can react with both acids and bases?

Accepted Answer

$$\mathrm{Al}_2\mathrm{O}_3$$

Question 7

Which of the following ions is smallest in size, given they are all isoelectronic: $$\mathrm{Na}^+$$, $$\mathrm{Mg}^{2+}$$, $$\mathrm{Al}^{3+}$$, $$\mathrm{F}^-$$?

Accepted Answer

$$\mathrm{Al}^{3+}$$

Question 8

Which of the following best explains why the melting point of Group 1 metals decreases down the group?

Accepted Answer

The strength of the metallic bond decreases as the number of electron shells increases.

Question 9

Which of the following statements about halogen reactivity is correct?

Accepted Answer

Halogens higher up in the group are more reactive because they gain electrons more easily.

Question 10

Which of the following best describes the trend in ionization energy across a period?

Accepted Answer

Ionization energy increases due to increased nuclear charge and constant shielding.

Question 11

Which of the following best explains why non-metals are poor conductors of electricity?

Accepted Answer

They have tightly held valence electrons and lack free electrons.

Question 12

Which of the following equations represents the first ionization energy of sodium?

Accepted Answer

$$\mathrm{Na}(g) \rightarrow \mathrm{Na}^+(g) + e^-$$

Question 13

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

Accepted Answer

Metallic character decreases due to increased nuclear charge and decreased atomic radius.

Question 14

Which of the following is a correct statement about the position of calcium (atomic number 20) in the periodic table?

Accepted Answer

It is in Group 2 and Period 4.

Question 15

Which of the following best explains why the ionic radius of $$\mathrm{O}^{2-} is $$larger than that of $$\mathrm{F}^-$$, even though both are isoelectronic?

Accepted Answer

$$\mathrm{F}^-$$ has more protons, pulling electrons closer and making it smaller.

Question 16

Which of the following best describes the chemical property of metalloids?

Accepted Answer

They can both lose and gain electrons, showing properties of both metals and non-metals.

Question 17

Which of the following reactions demonstrates the amphoteric nature of aluminum oxide?

Accepted Answer

Both reactions above demonstrate amphoteric behavior.

Question 18

Which of the following best explains why the melting point of Group 17 elements increases down the group?

Accepted Answer

The intermolecular forces increase due to more electrons, requiring more energy to melt.

Question 19

Which of the following best describes the trend in atomic radius down a group?

Accepted Answer

Atomic radius increases due to more electron shells and increased shielding effect.

Periodicity and Periodic Trends in the Periodic Table

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