1.3 Bonding Flashcards

1
Q

What is ionic bonding

A

Strong electrostatic forces of attraction between oppositely charged ions held in lattice

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2
Q

Give an example of an ionically bonded substance

A

NaCl

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3
Q

How high are ionically bonded substances bp and mp? Why?

A

High as it takes lots of energy to break strong electrostatic forces of attraction between oppositely charged ions

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4
Q

Do ionic compounds conduct electricity? why?

A

Yes when molten/in solution as the ions are free to move and carry charge (don’t when solid)

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5
Q

What is simple molecular covalent bonding?

A

Strong covalent bonds between atoms, weak VDW forces of attraction between molecules

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6
Q

Are there any lone electrons in simple covalent bonding?

A

No - all involved in bonding

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7
Q

Can simple molecular covalent molecules conduct electricity? Why?

A

No all electrons used in bonding and aren’t free to move

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8
Q

Do simple molecular substances have a high/low mpt and bpt? Why?

A

Low- weak VDW forces of attraction between molecules that don’t take much energy to overcome (these are overcome rather than covalent bonds)

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9
Q

Describe macromolecular covalent bonding

A

Lattice of many atoms held together by strong covalent bonds

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10
Q

Do substances with macromolecular covalent bonds have high/low mpt and bpts? Why?

A

High, as it takes a lot of energy to overcome many strong covalent bonds

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11
Q

Do substances with macromolecular covalent bonds conduct electricity?

A

Most don’t as all electrons are used in bonding

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12
Q

Draw and describe structure of a diamond

A

3D tetrahedral structure of C atoms , with each C atom bonded to four others

Slide 26

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13
Q

Draw and describe structure of graphite

A

Similar to diamond - macromolecular covalent- but each C atom is only bonded to 3 others, so it is in layers

Weak VDW forces of attraction between layers mean they can slide over each other —> soft, slippery

One electron from each carbon is delocalised and can carry charge —> conducts electricity

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14
Q

Describe and draw metallic bonding

A

Lattice of positive metal ions strongly attracted to a sea of delocalised electrons.

Layers can slide over each other - malleable

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15
Q

Do metallic compounds have high/low bpt and mpts? Why?

A

High as strong forces of attraction between positive metal ions and negatively charged sea of delocalised electrons

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16
Q

Do metallic compounds conduct electricity? Why?

A

Yes as delocalised electrons can move throughout the metal to carry charge

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17
Q

How does the strength of metallic bonds change across the periodic table? Why?

A

Increases —> higher melting and boiling points, stronger

Higher charge on metal ions

More delocalised electrons per ion

Stronger forces of attraction between them

18
Q

Define electronegativity

A

The ability of an atom to attract the pair of electrons (electron density) in a covalent bond

19
Q

What affects electronegativity

A

Nuclear charge

Atomic radius

Electron shielding

20
Q

What is the most electronegative element?

A

Fluorine as it has the largest nuclear charge for its electron shielding, small atomic radius

21
Q

How do you get a non polar bond?

A

Both bonding elements have the same electronegativities

22
Q

When do you get a polar bond?

A

Bonding atoms have different electronegativities

23
Q

What is the strongest type of inter-molecular force?

A

Hydrogen bonding

24
Q

What is the weakest type of inter-molecular force?

A

VDW forces

25
Q

Describe VDW forces of attraction

A

Temporary dipoles are created by the random movement of electrons —> induces dipole in neighbouring molecules —> temporary induced dipole-dipole attraction aka VDW forces of attraction

26
Q

Are VDW forces greater in smaller or larger molecules?

A

Larger - more electrons

27
Q

Describe permanent dipole-dipole attraction

A

Some molecules with polar bonds have permanent dipole —> forces of attraction between those dipoles and those of neighbouring molecules

28
Q

What conditions are neeeded for hydrogen bonding to occur?

A

O-H, N-H, F-H bond, lone pair of electrons on O,F,N

Because O,N,F are highly electronegativite, H nucleus is left exposed

Strong forces of attraction between H nucleus and lone pair of electrons on O, N, F

29
Q

Draw a diagram of hydrogen bonding

A

Slide 60

30
Q

Why is ice less dense than liquid water?

A

In liquid water, hydrogen bonds constantly break and reform as molecules move about

In ice the hydrogen bonds hold the molecules in fixed positions this makes them slightly further apart than in liquid water

31
Q

What is a dative/Co-ordinate covalent bond? When is it formed?

A

Formed when an electron deficient atom/ion accepts a lone pair of electrons from an atom/ion with a lone pair of electrons (not used in bonding)

32
Q

Draw the formation of a dative covalent bond in ammonia

A

Slide 65

33
Q

What does the shadow of molecules depend on?

A

Number of electrons in the valence shell of the central atom

Number of these electrons which are on bonded or lone pairs

34
Q

What does the electron pair repulsion theory state?

A

That electrons pairs will take up positions as far away from each other as possible, to minimise the repulsive forces between them

35
Q

Which experience the most repulsion?

Lone pair - lone pair
Bonded pair - bonded pair
Lone pair - bonded pair

A

LP- LP repulsion strongest

LP-BP repulsion middle

BP-BP repulsion weakest

36
Q

What is the shape, diagram and bond angle in a shape with 2 bonded pairs and 0 lone pairs?

A

Linear

180

37
Q

What is the shape, diagram and bond angle in a shape with three bonding pairs and 0 lone pairs?

A

Trigonal planar

120

38
Q

What is the shape diagram and bond angle in a shape with 4 bonded pairs and 0 lone pairs?

A

Tetrahedral

109.5

39
Q

What is the shape diagram and bond angle in a shape with 5 bonded pairs and 0 lone pairs?

A

Trigonal bipyramid

90 and 120

40
Q

What is the shape diagram and bond angle in a shape with 6 bonded pairs and 0 lone pairs?

A

Octahedral

90