Question 1

Which of the following best describes an antibonding orbital?

Accepted Answer

An orbital in which electron charge is concentrated on the far side of nuclei, drawing the nuclei apart.

Question 2

Calculate the change in enthalpy for the combustion of ethane: $$\mathrm{C_2H_4 + 3O_2 \rightarrow 2CO_2 + 2H_2O}.$$

Accepted Answer

$$-1275\ \mathrm{kJ/mol}$$

Question 3

How many aluminum atoms are there in $$3.50\ \mathrm{g} of$$ $$\mathrm{Al_2O_3}$$?

Accepted Answer

$$4.90 	imes 10$$^{22}$$

Question 4

Calculate the percent by weight of carbon in $$154\ \mathrm{g} of$$ $$\mathrm{C_4H_8O_3}.$$

Accepted Answer

$$46\%$$

Question 5

A covalent compound contains $$14.4\%$$ hydrogen and $$85.6\%$$ carbon by mass. What is the empirical formula?

Accepted Answer

$$\mathrm{CH}$$

Question 6

What is the ground state electron configuration of a phosphorus atom?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^3$$

Question 7

How are the ‘actual nuclear charge’ and the ‘effective nuclear charge’ experienced by an electron in a many electron atom related?

Accepted Answer

A, B and C are correct; it depends on the number of protons and electrons.

Question 8

An electron in a hydrogen atom releases $$1.817 	imes 10$$^{-22}$$\ \mathrm{kJ} of $$energy when transitioning to $$n=3. $$What energy level did the electron originate from?

Accepted Answer

$$n = 6$$

Question 9

Chromium must absorb radiation with minimum energy $$7.02 	imes 10$$^{-19}$$\ \mathrm{J} to $$eject electrons via the photoelectric effect. Which statement is true?

Accepted Answer

Electrons are ejected only when chromium is irradiated with light whose frequency is greater than $$1.06 	imes 10$$^{15}$$\ \mathrm{s}^{-1}$$ can be explained only if light is treated as a wave.

Question 10

What are the principal quantum number ($$n) $$and angular momentum quantum number ($$l) $$for the outermost electron in an arsenic atom in the ground state?

Accepted Answer

$$n = 5,\ l = 1$$

Question 11

Which statement is true regarding cations and anions?

Accepted Answer

Cations are always smaller than the neutral atom due to a decrease in the number of electrons resulting in a greater effective nuclear charge experienced by the most loosely bound electron.

Question 12

Which of the following are classified correctly?
I) $$\mathrm{HCl} (aq$$): Pure substance
II) Oxygen ($$\mathrm{O_2$}) (g$$): Pure substance
III) $$\mathrm{CH_4$}$$: Molecule

Accepted Answer

II only

Question 13

Which statement is true regarding the ground state electron configuration for calcium?

Accepted Answer

There are 2 electrons in s orbitals.

Question 14

Draw the Lewis structure for $$\mathrm{NH_3$}$$ and select the correct description of the electrons around the central atom.

Accepted Answer

Three single bonds, no double bonds, and one lone pair.

Question 15

What is the identity of the element if its atoms weigh $$1.9934 	imes 10$$^{-23}$$\ \mathrm{g} on $$average?

Accepted Answer

Astatine

Question 16

Why do ionic compounds generally have higher melting points than covalent compounds, as seen in the melting points of $$\mathrm{NaCl}$$ ($$801^\circ\mathrm{C}) $$and $$\mathrm{Cl_2$}$$ ($$-101.5^\circ\mathrm{C}$$)?

Accepted Answer

This is because covalent bonds are weaker than ionic bonds.

Question 17

Which of the following is the correct bond order for $$\mathrm{F_2$}$$ based on its molecular orbital diagram?

Accepted Answer

$$1$$

Question 18

How many resonance structures can be drawn for $$\mathrm{SO_3$}$$?

Accepted Answer

3

Question 19

Given the molecular orbital diagram for $$\mathrm{F_2$}$$, which orbitals are filled with electrons?

Accepted Answer

$$\sigma_{2s}$$, $$\sigma_{2p}$$, $$\pi_{2p}$$, and $$\pi_{2p}^*$$

General Chemistry Study Guidance: Bonding, Structure, and Atomic Properties

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