L8 & 9: Covalent Bonding

Question 1

True or false: In covalent bonding, electron pairs are shared by both participating atoms

Answer 1

True

Question 2

True or false: Covalent bonds are directional

Answer 2

True

Question 3

True or false: Covalent bonds form between metals and non-metals

Answer 3

False. Covalent bonds form between the atoms of the same or different non-metal elements

Question 4

True or false: Covalent bonding is found in organic compounds

Answer 4

True

Question 5

True or false: When atoms interact to form molecules, the overall number of orbitals must remain the same

Answer 5

True

Question 6

What is a Lewis Structure?

Answer 6

A graphic representation of the valence electrons of an atom. Each electron is represented by dots and crosses.

Question 7

True or false: Covalent bonding is favoured by atoms with low ionisation energy

Answer 7

False. Covalent bonding is favoured by those with high ionisation energy

Question 8

True or false: Covalent bonding is favoured by atoms of equal electron affinity and equal electronegativity

Answer 8

True

Question 9

True or false: Covalent bonding is favoured by atoms with a high nuclear charge

Answer 9

True

Question 10

True or false: Covalent bonding is favoured by atoms with a large atomic size

Answer 10

False. Covalent bonding is favoured by atoms with a small atomic size

Question 11

True or false: Most MCQ options that say “always” or “never” are wrong

Answer 11

True

Question 12

Fill in the gap:

Covalent compounds are __________ electrical conductors.

Answer 12

poor

Question 13

Fill in the gap:

Covalent compounds tend to have ____(1)____ melting points and ____(2)_____ boiling points

Answer 13

(1) low

(2) low

Question 14

If covalent bonds are strong, why do covalent compounds have low melting and boiling points?

Answer 14

Although the molecules are strong, the non-covalent intermolecular forces that hold the covalent molecules together are weak

Question 15

True or false: Covalent compounds are insoluble

Answer 15

Sometimes soluble; sometimes insoluble - depends on the intermolecular bonding with solvent

Question 16

How do you get a polar covalent bond?

Answer 16

Between atoms that have a significant difference in electronegativity, but not enough to form an ionic bond.

Question 17

Covalent or ionic?

High melting point, high boiling point

Answer 17

Ionic

Question 18

Covalent or ionic?

Conduct electricity when melted

Answer 18

Ionic

Question 19

Covalent or ionic?

Many soluble in non-polar liquids but not in water

Answer 19

Covalent

Question 20

Covalent or ionic?

Poor electrical conductors in any phase

Answer 20

Covalent

Question 21

Covalent or ionic?

Solids, liquids or gases

Answer 21

Covalent

Question 22

Covalent or ionic?

Crystalline solids

Answer 22

Ionic

Question 23

Covalent or ionic?

Answer 23

Many soluble in water but not in non-polar solvents

Question 24

True or false: When one atom donates both electrons to a covalent bond, it is known as a dative covalent bond

Answer 24

True. The atom that supplies the shared pair of electrons is known as the donor and the other atom is the acceptor - simples!

Question 25

Which 3 polyatomic ions are found with dative covalent bonding?

Answer 25

1) Transition metal complex ions 2) Nitrogen-containing complexes (such as the ammonium ion) 3) Hydroxonium ion

Question 26

True or false: Carbon monoxide and nitric acid display dative covalent bonding

Answer 26

True

Question 27

What are the 2 key requirements for a dative covalent bond to form?

Answer 27

1) The donor must have a lone pair of e- | 2) The acceptor must have a vacant orbital to house the donated pair

Question 28

How is ammonium formed?

Answer 28

Ammonia forms a dative covalent bond with H+. Ammonia is the donor and H+ is the acceptor

Question 29

How are complex ions formed?

Answer 29

When transition metal ions and Al3+ are dissolved in water

Question 30

Are the melting and boiling points of a co-ordinate compound higher or lower than that of a purely covalent compound?

Answer 30

Higher

Question 31

Are the melting and boiling points of a co-ordinate compound higher or lower than that of an ionic compound?

Answer 31

Lower

Question 32

Are co-ordinate compounds electrical conductors?

Answer 32

No

Question 33

What physical states can co-ordinate compounds exist in?

Answer 33

Solid, liquid, or gas

Question 34

What is the solubility of co-ordinate compounds?

Answer 34

Soluble in non-polar solvents; less soluble in polar solvents (can react with water)

Question 35

Where do dative bonds occur in biology?

Answer 35

When biological molecules bind to metal ion-containing cofactors

Question 36

The function of the drug dimercaprol depends on its ability to form dative covalent bonds. What is the function of dimercaprol?

Answer 36

Treats mercury and arsenic poisoning

Question 37

The function of the drug desferoxamine depends on its ability to form dative covalent bonds. What is the function of desferoxamine?

Answer 37

Treats iron overdose

Question 38

The function of the drug d-penicillinamine depends on its ability to form dative covalent bonds. What is the function of d-penicillinamine?

Answer 38

Treats copper and arsenic poisoning

Question 39

The function of the drug cis-platin depends on its ability to form dative covalent bonds. What is the function of cis-platin?

Answer 39

Anticancer agent

Question 40

True or false: Valence Shell Electron Pair Repulsion (VESPR) theory can predict the shape of a molecule

Answer 40

True

Question 41

If a molecule has only bonding pairs of electrons, what are the 5 shapes the molecule could assume? What are the bond angles of each shape?

Answer 41

1) Linear (180) 2) Trigonal planar (120) 3) Tetrahedral (109.5) 4) Trigonal bipyramidal (90 and 120) 5) Octahedral (90)

Question 42

How do you predict whether a molecule is polar?

Answer 42

1) Are the bonds polar? If not, the molecule will not be polar 2) What shape is the molecule? Do the dipole cancel each other out?