Question 1

Which of the following statements best describes the difference between an s orbital and a p orbital?

Accepted Answer

An s orbital is spherical, while a p orbital is dumbbell-shaped.

Question 2

What is the electron configuration of a neutral carbon atom?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^2$$

Question 3

Which hybridization is found in the carbon atoms of ethylene ($$C_2H_4$$)?

Accepted Answer

$$sp^2$$

Question 4

How many valence electrons does phosphorus have, and how many bonds does it typically form to achieve an octet?

Accepted Answer

5 valence electrons; forms 3 bonds

Question 5

Which of the following best explains why the bond angle in methane ($$CH_4) is $$approximately $$109.5^\circ$$?

Accepted Answer

The four $$sp^3$$ hybrid orbitals arrange themselves as far apart as possible, forming a tetrahedral geometry.

Question 6

In the molecular orbital theory for the $$H_2$$ molecule, what is the main reason the bond forms?

Accepted Answer

The bonding molecular orbital is lower in energy than the separate atomic orbitals, resulting in a net release of energy.

Question 7

Which of the following correctly matches the element with the number of covalent bonds it typically forms in organic molecules?

Accepted Answer

Nitrogen: 3

Question 8

What is the hybridization of the central atom in formaldehyde ($$CH_2O$$), and what is the geometry around the carbon?

Accepted Answer

sp$$^2$$; trigonal planar

Question 9

Which of the following best describes a $$\pi$$ bond in ethylene ($$C_2H_4$$)?

Accepted Answer

A $$\pi$$ bond is formed by the sideways overlap of unhybridized $$p$$ orbitals on adjacent carbon atoms.

Question 10

A molecule of carvone ($$C_{10}H$$_{14}$$O$) is responsible for the odor of spearmint. If a line-bond structure shows a carbon atom at an intersection with no explicit hydrogens, how many hydrogens are attached to that carbon if it has three bonds to other carbons?

Accepted Answer

One hydrogen

Question 11

Which of the following is the correct order of filling for electron orbitals according to the Aufbau principle?

Accepted Answer

$$1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p \rightarrow 4s \rightarrow 3d$$

Question 12

Which of the following best explains why the $$C-H$$ bond in methane is stronger than the $$C-H$$ bond in ethylene?

Accepted Answer

In methane, the $$C-H$$ bond is formed by overlap of $$sp^3$$ hybrid orbitals, which have more s character and better overlap with hydrogen's $$1s$$ orbital.

Question 13

Which of the following statements about lone pairs is correct?

Accepted Answer

Lone pairs are nonbonding pairs of electrons localized on a single atom.

Question 14

A molecule has a central atom with two regions of electron density. What is the expected hybridization and geometry?

Accepted Answer

$$sp$$; linear

Question 15

Which of the following best describes the energy change when a covalent bond forms between two hydrogen atoms?

Accepted Answer

Energy is released, and the system becomes more stable.

Question 16

Which of the following is a correct condensed structural formula for 2-methylbutane?

Accepted Answer

$$CH_3CH(CH_3$)CH_2CH_3$$

Question 17

Which of the following elements is most likely to form two covalent bonds in organic molecules?

Accepted Answer

Oxygen

Question 18

In the context of organic chemistry, which of the following best describes a sigma ($$\sigma) $$bond?

Accepted Answer

A $$\sigma$$ bond is formed by head-on overlap of atomic orbitals along the internuclear axis.

Question 19

Which of the following best explains why the $$sp^2$$ hybrid orbitals in ethylene are arranged at $$120^\circ$$ angles?

Accepted Answer

To minimize electron pair repulsion, the three $$sp^2$$ hybrid orbitals arrange themselves in a trigonal planar geometry.

Question 20

Which of the following is true regarding the electron density in an atom?

Accepted Answer

Electron density is highest near the nucleus and decreases with distance from the nucleus.

Organic Chemistry Chapter 1: Structure and Bonding - Study Notes

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