AP Chemistry: 1.8 Valence Electrons and Ionic Compounds - Exam Style questions with Answer- MCQ

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Question

Which of the following best helps explain why an atom of $Rb$ gas more easily loses an electron in a chemical reaction than an atom of $Li$ gas?

A. $Rb$ has a higher electronegativity than $Li$ has.

B. The $Rb$ atom has a greater number of valence electrons than the $Li$ atom has.

C. The nucleus of the $Rb$ atom has a greater number of protons and neutrons than the nucleus of the $Li$ atom has.

D. In the $Rb$ atom the valence electron is farther from its nucleus than the valence electron of $Li$ is from its nucleus.

▶️Answer/Explanation

Ans: C

Because the $Rb$ electron is farther from its nucleus, there is a weaker attraction and it is easier to lose.

Question

$Rb$ reacts with $O$ in a mole ratio of $2$ to $1$ , forming the ionic compound ${Rb}_{2} O$ . Which of the following elements will react with $O$ in a mole ratio of $2$ to $1$ , forming an ionic compound, and why?

A. $S$ , because it is in the same group as $O$ .

B. $Cs$ , because it is in the same group as $Rb$ .

C. Sr , because it is in the same period as $Rb$ .

D. $Br$ , because the atomic mass of $Br$ is similar to that of $Rb$ .

▶️Answer/Explanation

Ans: B

$Cs$ and $Rb$ have the same number of valence electrons because they are in the same group in the periodic table. Both of these elements can transfer one electron to a nonmetal when forming ionic compounds.

Question

What charge does $Al$ typically have in ionic compounds, and why?

positive 1

, because in the ground state it has one unpaired electron.

positive 1

positive 2

, because it has two electrons in the

2 s

subshell.

2 s

positive 3

, because it has three valence electrons.

positive 3

positive 4

, because it is in the fourth row of the periodic table.

▶️Answer/Explanation

Ans: C

The valence electrons of metal atoms are the farthest from the nucleus and are the most easily removed.

Question

Based on the ionization energies of element X given in the table above, which of the following is most likely the empirical formula of an oxide of element X?
(A)$ XO_{2}$
(B) $X_{2}$O
(C) $X_{2}O_{3}$
(D) $X_{2}O_{5}$

▶️Answer/Explanation

Ans:A

Question

The first five ionization energies of an unknown element are listed in the table above. Which of the following statements correctly identifies the element and cites the evidence supporting the
identification?

(A) Na, because of the large difference between the first and the second ionization energies

(B) Al, because of the large difference between the third and fourth ionization energies

(C) Si, because the fifth ionization energy has the greatest value

(D) P, because a neutral atom of P has five valence electrons

▶️Answer/Explanation

Ans:B

Question

The ionization energies of an unknown element, X, are listed in the table above. Which of the following is the most likely empirical formula of a compound formed from element X and phosphorus, P ?
(A) $XP$
(B) $X_{3}P$
(C) $X_{3}P_{2}$
(D) $X_{3}P_{4}$

▶️Answer/Explanation

Ans:C

AP Chemistry: 1.8 Valence Electrons and Ionic Compounds – Exam Style questions with Answer- MCQ

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