Unit 1 Reviewer For Final Exam

Question 1

What is the central atom in the Lewis structure of carbon dioxide?

Answer 1

Carbon

Carbon is the central atom connected to two oxygen atoms

Question 2

How many electrons are needed for a complete octet in the Lewis structure?

Answer 2

8 electrons

The octet rule states that atoms tend to prefer having eight electrons in their valence shell

Question 3

What are the two main groups of organic compounds?

Answer 3

Hydrocarbons and compounds with heteroatoms

Hydrocarbons contain only hydrogen and carbon, while heteroatoms include elements like oxygen and nitrogen

Question 4

What defines the classification of hydrocarbons?

Answer 4

Saturated and unsaturated

Saturated hydrocarbons contain only single bonds, while unsaturated hydrocarbons contain double or triple bonds

Question 5

Name three common heteroatoms found in organic compounds.

Answer 5

• Oxygen
• Nitrogen
• Halogens (Cl, Br, I, F)

Sulfur and phosphorus are also considered heteroatoms

Question 6

What are the two types of hydrocarbons?

Answer 6

• Aliphatics
• Aromatics

Aliphatics include alkanes, alkenes, and alkynes

Question 7

What is the functional group of alcohols?

Answer 7

Hydroxyl group (-OH)

Alcohols are characterized by the presence of a hydroxyl group

Question 8

What is the process of forming products from reactants in organic chemistry called?

Answer 8

Reaction mechanism

This involves the step-by-step events of bond breaking and forming

Question 9

How are organic reactions classified?

Answer 9

• Addition
• Elimination
• Substitution
• Rearrangement
• Oxidation
• Reduction

These classifications depend on the type of transformation occurring

Question 10

What occurs in an addition reaction?

Answer 10

Increase in the number of atoms or groups attached to carbon

This typically results in a saturated product from an unsaturated substrate

Question 11

What happens during an elimination reaction?

Answer 11

An atom or group of atoms is removed from the substrate

This results in a more unsaturated product

Question 12

What characterizes a substitution reaction?

Answer 12

Replacement of an atom or group of atoms in the substrate

For example, a chlorine atom can be replaced by a hydroxyl group

Question 13

What is a rearrangement reaction?

Answer 13

Migration of an atom or group of atoms from one atom to another

This can involve the movement of atoms within a molecule

Question 14

Define oxidation in organic chemistry.

Answer 14

Increase in oxygen content and/or a decrease in hydrogen content

Oxidation reactions are often associated with the loss of electrons

Question 15

Define reduction in organic chemistry.

Answer 15

Increase in hydrogen content and/or a decrease in oxygen content

Reduction reactions are often associated with the gain of electrons

Question 16

What are the two types of bond cleavage in reaction mechanisms?

Answer 16

• Homolytic cleavage
• Heterolytic cleavage

Homolytic cleavage results in radicals, while heterolytic cleavage results in charged intermediates

Question 17

What is a nucleophilic reagent?

Answer 17

A substance that loves electrons and can form bonds by donating electron pairs

Nucleophiles attack positively charged atoms or regions of low electron density

Question 18

What is an electrophilic reagent?

Answer 18

An electron-deficient species that can accept electron pairs

Electrophiles typically attack negatively charged regions

Question 19

What is the significance of reaction intermediates?

Answer 19

They are formed in one step and consumed in a later step of the reaction mechanism

Understanding intermediates helps clarify the steps of the overall reaction

Question 20

What is the rate-determining step in a reaction mechanism?

Answer 20

The slowest step in the mechanism

This step limits the overall rate of the reaction

Question 21

What does tetravalent mean in relation to carbon?

Answer 21

Carbon can form four covalent bonds with other atoms such as hydrogen, oxygen, nitrogen, and with itself.

Question 22

What types of molecular structures can carbon form?

Answer 22

• Linear
• Branched
• Cyclic

Question 23

What happens to the diversity of molecular structures when carbon forms single, double, and triple bonds?

Answer 23

It can form more diverse molecular structures.

Question 24

Who were the two chemists that recognized carbon’s tetravalency?

Answer 24

Kekulé and Couper.

Question 25

What is the significance of noble gases in Lewis’s theory?

Answer 25

Noble gases have completely filled valence shells, indicating a high degree of stability.

Question 26

What is the purpose of the Lewis structure?

Answer 26

To unify many observations about the chemical reactions of the elements.

Question 27

Fill in the blank: An atom becomes negatively charged (-) when it ______.

Answer 27

loses an electron.

Question 28

Fill in the blank: An atom becomes positively charged (+) when it ______.

Answer 28

gains an electron.

Question 29

What type of bond is formed when two atoms share electrons?

Answer 29

Covalent bond.

Question 30

What is an ionic bond?

Answer 30

A bond formed when an atom loses or gains an electron.

Question 31

What differentiates a polar covalent bond from a non-polar covalent bond?

Answer 31

Polar covalent bonds involve unequal sharing of electrons, while non-polar covalent bonds involve equal sharing.

Question 32

How do you determine the number of electrons to be used in connecting atoms in a molecule?

Answer 32

By adding all the numbers of valence electrons of the atoms in the molecule.

Question 33

How many valence electrons does carbon have?

Answer 33

4.

Question 34

How many valence electrons does oxygen have?

Answer 34

6.

Question 35

What is the total number of electrons in the Lewis structure of carbon dioxide (CO2)?

Answer 35

16.

Question 36

What is the Lewis dot symbol for Lithium?

Answer 36

Li .

Question 37

What is the Lewis dot symbol for Oxygen?

Answer 37

::O:

Question 38

What is the Lewis dot symbol for Neon?

Answer 38

::Ne::