Topic 3 - Chemical Bonding Flashcards

1
Q

What are ionic compounds?

A

Oppositely charged ions held together by electrostatic attractions.

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2
Q

Can ionic compounds conduct electricity?

A

Only in aqueous solution or when molten.

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3
Q

What are the melting points of ionic compounds like?

A

High.

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4
Q

Why do ionic compounds have high melting points?

A

Many, strong electrostatic forces between oppositely charged ions that need lots of energy to overcome.

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5
Q

Why do ionic compounds conduct electricity when molten?

A

The ions are free to move.

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6
Q

Why do ionic compounds conduct electricity when in aqueous solution?

A

Water molecules are polar and can attract the positive and negative ions and break the structure so the ions are free to move.

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7
Q

Why are ionic compounds brittle?

A

When struck, the layers slide and positive ions get next to positive ions and repel and break the structure.

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8
Q

What is a way to show evidence for charged particles?

A

Electrolysis of copper(II)chromate(VI) on wet filter paper.

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9
Q

What color is copper(II)chromate(VI)?

A

Green.

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10
Q

What happens when a drop of green copper(II)chromate(VI) is placed on wet filter paper and electricity is passed through it?

A

The ions start to separate.

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11
Q

What is the charge on a copper(II) ion?

A

2+

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12
Q

Where do the Cu2+ ions go?

A

They move toward the negative cathode.

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13
Q

What color is the Cu2+ solution?

A

Blue.

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14
Q

What is the charge on a chromate(VI) ion?

A

2-

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15
Q

Where do the CrO4^2- ions go?

A

The move towards the positive anode.

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16
Q

What color is the CrO4^2- solution?

A

Yellow.

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17
Q

What is covalent bonding?

A

The sharing of electrons in order for the atoms to obtain a full outer shell.

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18
Q

Where is the electrostatic attraction in a covalent bond?

A

Between the shared electrons and the positive nucleus.

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19
Q

How many types of covalent bonds are there, and what are they?

A

3
Single, double, and triple bonds.

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20
Q

What is a dative covalent bond?

A

Where one atom donates 2 electrons to an atom or ion to form a bond.

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21
Q

What is an alternate name for a dative covalent bond?

A

Coordinate bond.

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22
Q

How is a coordinate bond represented in a diagram?

A

An arrow.

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23
Q

What is bond enthalpy?

A

The strength of the bond.

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24
Q

What is the relationship between bond enthalpy and the length of the bond?

A

The shorter the bond the higher the bond enthalpy.

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25
Q

Why does a shorter bond length lead to higher bond enthalpy?

A

Greater electron density between atoms = stronger attractive force = atoms are pulled closer together = shorter bond length = higher bond enthalpy.

26
Q

What causes bond length?

A

Attractive forces and repulsive forces.

27
Q

What two things determine the shape of a molecule?

A

The number of bond pairs and lone pairs of electrons.

28
Q

What is the bond angle in a tetrahedral molecule?

A

109.5*

29
Q

What is the general rule for no. of lone pairs and bond angles?

A

For each lone pair added, reduce the bond angle by 2.5*.

30
Q

What shape and bond angles will a molecule with 4 bond pairs and no lone pairs of electrons have?

A

Tetrahedral. 109.5*.

31
Q

What is the shape and bond angles of a molecule with 2 bond pairs and no lone pairs of electrons?

A

Linear. 180*.

32
Q

What shape and bond angles will a molecule with 3 bond pairs and no lone pairs of electrons have?

A

Trigonal Planar. 120*.

33
Q

What shape and bond angles will a molecule with 5 bond pairs and no lone pairs of electrons have?

A

Trigonal Bipyramidal. 90* and 120*.

34
Q

What shape and bond angles will a molecule with 6 bond pairs and no lone pairs of electrons have?

A

Octahedral. 90*.

35
Q

What shape and bond angles will a molecule with 3 bond pairs and 1 lone pairs of electrons have?

A

Pyramidal. 107*.

36
Q

What shape and bond angles will a molecule with 2 bond pairs and 2 lone pairs of electrons have?

A

Bent. 104.5*.

37
Q

What shape and bond angles will a molecule with 3 bond pairs and 2 lone pairs of electrons have?

A

Trigonal Planar. 120*.

38
Q

What shape and bond angles will a molecule with 4 bond pairs and 2 lone pairs of electrons have?

A

Square Planar. 90*.

39
Q

What are two examples of giant covalent structures?

A

Graphite and diamond.

40
Q

Why does graphite have a high melting point?

A

Lots of strong covalent bonds.

41
Q

Why do graphite layers slide easily?

A

Weak forces between the layers.

42
Q

Can graphite conduct electricity?

A

Yes

43
Q

Why can graphite conduct electricity?

A

Delocalized electrons float between the layers and can carry a charge.

44
Q

Why does graphite have a low density?

A

The layers are far apart in comparison to covalent bond length.

45
Q

Is graphite soluble or insoluble?

A

Insoluble.

46
Q

Why can diamond conduct heat well?

A

Tightly packed, rigid arrangement.

47
Q

Why does diamond have a very high melting point?

A

Lots of strong covalent bonds.

48
Q

Is diamond soluble or insoluble?

A

Insoluble.

49
Q

Can diamond conduct electricity?

A

No

50
Q

Why can’t diamond conduct electricity?

A

No delocalised electrons.

51
Q

What other substance has a similar shape and properties to diamond?

A

Silicon(IV) dioxide.

52
Q

What is a sigma bond?

A

When two orbitals overlap.

53
Q

What are pi bonds?

A

The parallel overlap of 2 p orbitals.

54
Q

What bonds does a double bond contain?

A

A sigma and a pi bond.

55
Q

What is benzene?

A

A cyclic, planar molecule with the formula C6H6.

56
Q

What is electronegativity?

A

The ability for an atom to attract electrons towards itself in a covalent bond.

57
Q

Where are the most electronegative elements found in the periodic table?

A

Top righthand corner.

58
Q

What is the most electronegative element in the periodic table?

A

Fluorine.

59
Q

What is the Pauling Scale?

A

A scale that quantifies how electronegative something is with a higher number meaning more electronegativity.

60
Q
A