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Chemistry revision > Bonding > Flashcards

Bonding Flashcards

1
Q

What is ionic bonding?

A

strong electrostatic forces of attraction between oppositely charged ions held in a lattice

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2
Q

Give an example of an

ionically bonded substance

A

NaCl (sodium chloride - salt)

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3
Q

How high are ionically

bonded substances’ bp and mp? Why?

A

High - 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 van der Waals 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 van der Waals 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

Describe the structure

of diamond

A

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

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13
Q

Describe the 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 van der Waals 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 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

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 force of attraction between them

18
Q

Define electronegativity

A

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

19
Q

What affects electronegativity? (3)

A

Nuclear charge
Atomic radius
Electron shielding

20
Q

What is the most

electronegative element?

A

Fluorine (4.0 on Pauling’s scale) → largest nuclear charge for its electron shielding, small atomic radius

21
Q

How do you get a nonpolar 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 IMF?

A

Hydrogen bonding

24
Q

What is the weakest type of IMF?

A

van der Waals forces

25
Q

Describe van der Waals’ forces of attraction.

A

Temporary dipoles are created by the random movement of electrons → induces dipole in neighbouring molecule → temporary induced dipole-dipole attraction aka van der Waals forces of attraction

26
Q

Are Van der Waals 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 dipoles → forces of attraction
between those dipoles and those of neighbouring molecules

28
Q

What conditions are needed for hydrogen bonding to occur?

A

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

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

29
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

30
Q

What is a dative

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)

31
Q

What does the shape of molecules depend on?

A

Number of electrons in the valence shell of the central atom.
Number of these electrons which are in bonded or lone pairs

32
Q

What does the Electron Pair Repulsion Theory state?

A

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

33
Q

Which experience the most repulsion?

LP-LP, LP-BP, BP- BP

A

LP-LP repulsion strongest
LP-BP repulsion middle
BP-BP repulsion weakest

34
Q

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

A

Linear

180°

35
Q

What is the shape, and bond angle in a shape

with 3 bonding pairs and 0 lone pairs?

A

Trigonal planar

120°

36
Q

What is the shape, and bond angle in a shape

with 4 bonded pairs and 0 lone pairs?

A

Tetrahedral

109.5°

37
Q

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

A

Trigonal bipyramid

90° and 120°

38
Q

What is the shape, and bond angle in a shape

with 6 bonded pairs and 0 lone pairs?

A

Octahedral

90°

Chemistry revision (46 decks)

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