Question 1

Which statement best explains why atoms form molecules according to Gilbert Lewis's theory?

Accepted Answer

Atoms combine to achieve a more stable electron configuration, often becoming isoelectronic with a noble gas.

Question 2

Which of the following elements would have the following Lewis dot symbol: $$\mathrm{\cdot S \cdot} ($$with six dots around the symbol)?

Accepted Answer

Sulfur (S)

Question 3

What is the primary difference between an ionic bond and a covalent bond?

Accepted Answer

Ionic bonds involve the transfer of electrons due to large differences in electronegativity, while covalent bonds involve the sharing of electrons.

Question 4

Given the following electron configuration for fluorine: $$1s^2$$ $$2s^2$$ $$2p^5$$, how many valence electrons does fluorine have?

Accepted Answer

7

Question 5

Which of the following compounds is most likely to have a high melting point due to its ionic nature?

Accepted Answer

Na$$_2O$$

Question 6

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally, resulting in partial charges on the atoms.

Question 7

Rank the following bonds in order of decreasing bond length: $$\mathrm{C\equiv O}$$, $$\mathrm{C=O}$$, $$\mathrm{C-O}.$$

Accepted Answer

$$\mathrm{C-O} \u003e \mathrm{C=O} \u003e \mathrm{C\equiv O}$$

Question 8

Which element has the highest electronegativity according to the periodic trend?

Accepted Answer

Fluorine (F)

Question 9

A molecule has a difference in electronegativity of 2.5 between its atoms. What type of bond is most likely present?

Accepted Answer

Ionic

Question 10

Which of the following is the correct formula for calculating the formal charge on an atom in a Lewis structure?

Accepted Answer

$$\mathrm{Formal\ Charge = Valence\ Electrons - NonBonding\ Electrons - \frac{1}{2} 	imes Bonding\ Electrons}$$

Question 11

Which molecule below is an example of a resonance structure?

Accepted Answer

CO$$_3$$^{2-}$$ (carbonate ion)

Question 12

Which of the following is an exception to the octet rule due to an incomplete octet?

Accepted Answer

BF$$_3$$

Question 13

Which molecule is an example of an expanded octet?

Accepted Answer

SF$$_6$$

Question 14

How many covalent bonds does oxygen typically form according to the bond rules?

Accepted Answer

Two

Question 15

Which of the following best describes the Lewis structure of NH$$_4^+ ($$ammonium ion)?

Accepted Answer

Nitrogen atom with four hydrogen atoms and no lone pairs, enclosed in brackets with a positive charge.

Question 16

Which of the following steps is NOT part of the procedure for drawing a Lewis structure?

Accepted Answer

Assign formal charges to each atom.

Question 17

In the formaldehyde molecule (CH$$_2O$$), which Lewis structure is preferred based on formal charges?

Accepted Answer

The structure with all atoms having a formal charge of zero.

Question 18

Which of the following molecules contains a triple bond?

Accepted Answer

N$$_2$$

Question 19

Which statement about resonance structures is correct?

Accepted Answer

Resonance structures are two or more Lewis structures for a single molecule that cannot be represented accurately by only one Lewis structure.

Question 20

Which of the following is true regarding the placement of negative formal charges in Lewis structures?

Accepted Answer

Negative formal charges should be placed on the more electronegative atoms.

Covalent Bonding I: Basic Concepts – Study Notes

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