Chap 2: Covalent Compounds

Question 1

What is a bond pair?

Answer 1

Pair of valence electrons that is shared between atoms in a covalent bond

Question 2

What is Covalent bonding?

Answer 2

bonding resulting from the sharing of electrons between non-metal atoms

Question 3

How is a covalent bond formed?

Answer 3

A covalent bond is formed when non-metallic atoms share electrons in order to fill their valence shell.

The sharing is according to the octet rule.

Question 4

What is the octet rule?

Answer 4

States that atoms are most stable with 8 electrons in their outer shell

Question 5

What is the Lewis Structure?

Answer 5

Illustrate the number of valence electron that an aton has, represented by dots

Question 6

What does the Structural formula do?

Answer 6

Offer a clearer approach to representing molecules (lines) but do not provide information about valence electrons

Question 7

What does the molecular formula do?

Answer 7

Depicts the actual number of each type of element present in a compound, no information on bonding

Question 8

What is the number of bonds in a linear molecular bond?

Answer 8

0 lone pairs and 2 bonded pairs or 3 lone pairs and 1 bonding pair

Question 9

What is a lone pair?

Answer 9

The electron pairs of valence electrons not shared with another atom in a covalent bond

Question 10

What is the number of bonds in an inverted v-shaped molecular bond?

Answer 10

2 lone pairs and 2 bonded pairs

Question 11

What is the number of bonds in a tetrahedral molecular bond?

Answer 11

0 lone pairs and 4 bonded pairs

Question 12

What is the number of bonds in a pyramidal molecular bond?

Answer 12

1 lone bond and 3 bonded pairs

Question 13

What is a polar molecule?

Answer 13

• if the molecule is asymmetrical
• if the atoms are different

Question 14

What is a non-polar molecule?

Answer 14

• if the molecule is symmetrical
• if atoms are the same

Question 15

What is hydrogen bonding?

Answer 15

a special type of permanenet dipole-dipole attraction between molecules (not covalent) that results in from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom (FON)

Question 16

What is dispersion forces?

Answer 16

Dispersion forces are constantly moving, so there are moments when electrons in a molecule will concentrate in one region, creating a slightly negative and positive charge. This creates an instantaneous dipole.

Question 17

What are intermolecular forces?

Answer 17

Forces that attract adjacent molecules to each other

Question 18

What are intramolecular bonds?

Answer 18

bonding between atoms within a molecule

Question 19

What are permanent dipole-dipole attractions?

Answer 19

are a type of intermolecular force that are only formed from the electrostatic attraction between polar molecules

Question 20

What is the structure of diamonds?

Answer 20

Diamonds are made entirely out of a carbon covalent network lattice. Each carbon atom in the lattice is bonded to four other carbon atoms and organised into a 3D tetrahedral lattice stucture

Question 21

Why is a diamond hard and brittle?

Answer 21

The rigid 3D tetrahedral lattice structure of a diamond makes it hard, as when pressure is exerted on the structure, it is reduced by spreading it throughout the structure.

The rigid lattice structure will not allow a diamond to be bent.

Question 22

Why does diamond have a high melting point?

Answer 22

A lot of energy is required to disrupt the covalent bonds of the lattice

Question 23

Why does diamond not conduct electricity?

Answer 23

Each carbon takes part in four single covalent bonds. This means that there are no free electrons available to conduct electricity

Question 24

Why does a diamond have high thermal conductivity?

Answer 24

The strong covalent bonds can absorb a lot fo heat

Question 25

Why is a diamond insoluble?

Answer 25

The strength of the covalent bonds cannot be overcome by the intermolecular forces of a solvent like water

Question 26

What is the structure of graphite?

Answer 26

Graphite’s structure consists of layers of hexagonal, 2-dimensional carbon lattices held together by weak dispersion forces.

It is referred to as a covalent layer lattice

Question 27

Why does graphite have a high melting point?

Answer 27

A lot of energy is required to break the covalent bonds of the lattice

Question 28

Why does graphite have a high thermal conductivity?

Answer 28

When heat is applied the hexagonal lattice of covalently bonded atoms are able to vibrate about in a very strong fixed position passing on heat energy without having their covalent bonds broken

Question 29

Why does graphite have high electrical conductivity?

Answer 29

Graphite has delocalised electrons that can move through the structure and carry an electrical charge

Question 30

Why is graphite soft and slippery?

Answer 30

The layers of graphite held together by dispersion forces are not tightly packed as covalently bonded carbon atoms