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

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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4
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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5
Q

Are there any lone electrons in simple covalent bonding?

A

No- all involved in bonding

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6
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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7
Q

Do simple molecular substances have a high/low melting point and boiling point? 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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8
Q

How high are ionically bonded substances’ boiling point and melting point? Why?

A

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

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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 melting point and boiling points? 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 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 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 boiling point and melting points? 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 inter-molecular force?

A

Hydrogen bonding

24
Q

What is the weakest type of inter-molecular force?

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 stronger 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

Strong force of attraction between H nucleus and Lone pair of electrons on O, N, F

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/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)

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?

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 bonded 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°