L8 & 9: Covalent Bonding Flashcards

1
Q

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

A

True

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2
Q

True or false: Covalent bonds are directional

A

True

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3
Q

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

A

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

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4
Q

True or false: Covalent bonding is found in organic compounds

A

True

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5
Q

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

A

True

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6
Q

What is a Lewis Structure?

A

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

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7
Q

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

A

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

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8
Q

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

A

True

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9
Q

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

A

True

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10
Q

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

A

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

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11
Q

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

A

True

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12
Q

Fill in the gap:

Covalent compounds are __________ electrical conductors.

A

poor

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13
Q

Fill in the gap:

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

A

(1) low

(2) low

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14
Q

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

A

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

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15
Q

True or false: Covalent compounds are insoluble

A

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

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16
Q

How do you get a polar covalent bond?

A

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

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17
Q

Covalent or ionic?

High melting point, high boiling point

A

Ionic

18
Q

Covalent or ionic?

Conduct electricity when melted

A

Ionic

19
Q

Covalent or ionic?

Many soluble in non-polar liquids but not in water

A

Covalent

20
Q

Covalent or ionic?

Poor electrical conductors in any phase

A

Covalent

21
Q

Covalent or ionic?

Solids, liquids or gases

A

Covalent

22
Q

Covalent or ionic?

Crystalline solids

A

Ionic

23
Q

Covalent or ionic?

A

Many soluble in water but not in non-polar solvents

24
Q

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

A

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

25
Q

Which 3 polyatomic ions are found with dative covalent bonding?

A

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

26
Q

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

A

True

27
Q

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

A

1) The donor must have a lone pair of e-

2) The acceptor must have a vacant orbital to house the donated pair

28
Q

How is ammonium formed?

A

Ammonia forms a dative covalent bond with H+.

Ammonia is the donor and H+ is the acceptor

29
Q

How are complex ions formed?

A

When transition metal ions and Al3+ are dissolved in water

30
Q

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

A

Higher

31
Q

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

A

Lower

32
Q

Are co-ordinate compounds electrical conductors?

A

No

33
Q

What physical states can co-ordinate compounds exist in?

A

Solid, liquid, or gas

34
Q

What is the solubility of co-ordinate compounds?

A

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

35
Q

Where do dative bonds occur in biology?

A

When biological molecules bind to metal ion-containing cofactors

36
Q

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

A

Treats mercury and arsenic poisoning

37
Q

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

A

Treats iron overdose

38
Q

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

A

Treats copper and arsenic poisoning

39
Q

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

A

Anticancer agent

40
Q

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

A

True

41
Q

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?

A

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

42
Q

How do you predict whether a molecule is polar?

A

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?