Q: What is the total number of valence electrons in a molecule of C$$_2H$_6$$?

$$2 \times 4 + 6 \times 1 = 14$$

Question 1

Which of the following statements best describes the purpose of a Lewis Dot Structure?

Accepted Answer

It represents the valence electrons of atoms as dots, showing how atoms share or transfer electrons to form chemical bonds.

Question 2

How many valence electrons are present in a molecule of SF$$_6$$?

Accepted Answer

$$6 + 6 	imes 7 = 48$$

Question 3

Which element is most likely to be the central atom in a Lewis Dot Structure for the compound CH$$_2O$$?

Accepted Answer

Carbon, because it has the lowest electronegativity and is the lowest subscript in the formula.

Question 4

What is the electron group geometry and molecular shape of CO$$_2$$ according to VSEPR theory?

Accepted Answer

Linear, linear

Question 5

A molecule of NH$$_3$$ has which of the following molecular shapes and bond angles?

Accepted Answer

Trigonal pyramidal, $$107^\circ$$

Question 6

Which of the following molecules would experience hydrogen bonding as an intermolecular force?

Accepted Answer

NH$$_3$$

Question 7

Given the electronegativity values: H = 2.1, Cl = 3.0, what type of bond is present in HCl?

Accepted Answer

Polar covalent

Question 8

Which of the following best explains why CCl$$_4 is a $$nonpolar molecule even though it contains polar bonds?

Accepted Answer

The four C–Cl dipoles are arranged symmetrically and cancel each other out.

Question 9

Which intermolecular force is the strongest among the following options?

Accepted Answer

Hydrogen bonding

Question 10

A sample contains two molecules: H$$_2O $$and CH$$_4. $$Which statement best describes the types of intermolecular forces present?

Accepted Answer

H$$_2O $$experiences hydrogen bonding and dispersion forces; CH$$_4$$ experiences only dispersion forces.

Question 11

Which of the following molecules would have the highest boiling point due to intermolecular forces?

Accepted Answer

NH$$_3$$

Question 12

What is the total number of valence electrons in a molecule of C$$_2H$_6$$?

Accepted Answer

$$2 	imes 4 + 6 	imes 1 = 14$$

Question 13

Which of the following best describes the difference between intramolecular and intermolecular forces?

Accepted Answer

Intramolecular forces are the forces that hold atoms together within a molecule, while intermolecular forces are the forces between separate molecules.

Question 14

Which of the following substances would dissolve best in water?

Accepted Answer

Methanol (CH$$_3OH)$$

Question 15

Which molecule has a bent molecular shape due to the presence of lone pairs on the central atom?

Accepted Answer

H$$_2O$$

Question 16

What is the correct Lewis Dot Structure for a molecule of O$$_2$$?

Accepted Answer

$$\cdot\cdot O::O \cdot\cdot$$

Question 17

Which of the following molecules is nonpolar and experiences only dispersion forces?

Accepted Answer

CH$$_4$$

Question 18

A molecule has a central atom with three groups attached and no lone pairs. What is its electron group geometry and molecular shape?

Accepted Answer

Trigonal planar, trigonal planar

Question 19

Which of the following best explains why water (H$$_2O) $$has a higher boiling point than methane (CH$$_4$$)?

Accepted Answer

Water forms hydrogen bonds, which are stronger than the dispersion forces present in methane.

Molecular Shapes, Lewis Dot Structures, and Valence Electrons

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