Bonding - Physical 1 Flashcards

1
Q

what is a covalent bond between?

A

non metal and non metal

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1
Q

What is an ionic bond between?

A

metal and non metal

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2
Q

What is ionic bonding?

A

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

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3
Q

Give an example of an ionically bonded substance

A

NaCl (sodium chloride - salt)

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4
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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5
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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6
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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7
Q

Are there any lone electrons in simple covalent bonding?

A

No- all involved in bonding

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8
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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9
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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10
Q

Describe macromolecular covalent bonding

A

Lattice of many atoms held together by 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

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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13
Q

Draw and describe structure of diamond

A

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

check pic on google

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14
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 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

check pick on google

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15
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

check pic on google

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16
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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17
Q

Do metallic compounds conduct electricity? why?

A

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

18
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

19
Q

Define electronegativity

A

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

20
Q

What affects electronegativity? (3)

A

Nuclear charge Atomic radius Electron shielding

21
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

22
Q

How do you get a nonpolar bond?

A

Both bonding elements have the same electronegativities

23
Q

When do you get a polar bond?

A

Bonding atoms have different electronegativities

24
Q

What is the strongest type of inter-molecular force?

A

Hydrogen bonding

25
Q

What is the weakest type of inter-molecular force?

A

van der Waals forces

26
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

27
Q

Are Van der Waals forces greater in smaller or larger molecules?

A

Larger- more electrons

28
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

Key Points. Dipole-dipole interactions occur when the partial charges formed within one molecule are attracted to an opposite partial charge in a nearby molecule

29
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

30
Q

Draw a diagram of hydrogen bonding

A

please check on google

31
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

32
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)

33
Q

Draw the formation of a dative covalent bond in ammonia

A

check on google

34
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

35
Q

how do you work out what shape the molecule is?

A

add outer shell electron number of main atom to number of bonds etc then divide by 2

adjust accordingly for ions

36
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

37
Q

Which experience the most repulsion?
Lone pair-lone pair Lone pair-bonded pair Bonded pair- bonded pair

A

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

38
Q

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

A

Linear 180° - check for picture

39
Q

What is the shape, diagram and bond angle in a shape with 3 bonding pairs and 0 lone pairs?

A

Trigonal planar 120° - check for picture

40
Q

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

A

Tetrahedral 109.5° - check for picture

41
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° - check for picture

41
Q

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

A

Octahedral 90° - check for picture