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Chemistry A-Level OCR > 2.2.2 structure and bonding > Flashcards

2.2.2 structure and bonding Flashcards

1
Q

an ionic bond is…

A

a strong electrostatic force of attraction between oppositely charged ions

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2
Q

state and describe the structure of ionic compounds

A

giant ionic lattice where the positive ions attract the negative ions and are surrounded by them and vice versa

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3
Q

state and explain whether ionic compounds have a high or low melting and boiling points

A

high, the attraction between ions is very strong which means lots of energy is needed to overcome this force

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4
Q

state and explain the conduction of ionic compounds in both solid and liquid states

A

when solid there are no free ions to conduct electricity so the compound is a poor conductor

when molten the ions are free to move and conduct electricity so the compound is a good conductor

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5
Q

a covalent bond is…

A

a shared pair of electrons (the strong electrostatic force of attraction between a shared pair of electrons and the nuclei of the bonded atoms)

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6
Q

a dative covalent bond is…

A

formed when the shared pair of electrons in a covalent bond come from only one of the bonding atoms

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7
Q

a dative covalent bond could also be called…

A

co-ordinate bonding

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8
Q

give the names of the two covalent structures

A

giant covalent / macromolecular

simple molecular

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9
Q

describe the simple molecular structure

A

individual molecules with weak forces between them with atoms being joined by covalent bonds

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10
Q

state and explain wether simple molecular substances have a high or low melting and boiling points

A

low, there are weak London forces between molecules that need little energy to overcome

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11
Q

describe a giant covalent structure

A

lattice structure in which all atoms are joined to others by covalent bonds

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12
Q

state and explain whether simple molecular substances are good or poor conductors

A

poor, there are no free electrons to move and conduct electricity

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13
Q

state and explain whether giant covalent substances have high or low melting and boiling points

A

high, strong covalent bonds need lots of energy to overcome

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14
Q

state and explain whether giant covalent substances are poor or good conductors

A

poor, in most giant covalent substances there are no free electrons that can move and conduct electricity except in graphite where there are 3 carbon to carbon bonds with each 4th outer electron being able to move and conduct electricity

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15
Q

explain why graphite is malleable

A

graphite is formed in layers that are able to slide over each other easily

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16
Q

a metallic bond is…

A

the electrostatic force of attraction between positive metal ions and a sea of delocalised electrons

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17
Q

state and describe the structure of metallic substances

A

giant metallic, lattice structure of metal ions with outer shell electrons free to move through structure

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18
Q

state and explain whether metallic substances have high or low melting and boiling points

A

high, there is strong electrostatic force of attraction between the positive metal ions and sea of delocalised electrons that means lots of energy is needed to overcome this

19
Q

state and explain whether metallic substances are poor or good conductors

A

good, the sea of delocalised electrons are free to move through the structure and conduct electricity

20
Q

explain why metallic substances are malleable

A

the positive ions are all identical and formed in layers that allow the ions to slide easily over one and other

21
Q

from highest to lowest order the following by their repulsion
• lone pair to bond pair
• bond pair to bond pair
• lone pair to lone pair

A 
highest  
              lone pair to lone pair
              lone pair to bond pair
              bond pair to bond pair
lowest
22
Q

each lone pair reduces the bond angle by…

A

2.5°

23
Q

name the shape of a molecule with 2 bond pairs and 0 lone pairs and give the bond angle

A

linear 180°

24
Q

name the shape of a molecule with 3 bond pairs and 0 lone pairs and give the bond angle

A

trigonal planar 120°

25
Q

name the shape of a molecule with 4 bond pairs and 0 lone pairs and give the bond angle

A

tetrahedral 109.5°

26
Q

name the shape of a molecule with 3 bond pairs and 1 lone pair and give the bond angle

A

trigonal pyramidal 107°

27
Q

name the shape of a molecule with 2 bond pairs and 2 lone pairs and give the bond angle

A

bent 104.5°

28
Q

name the shape of a molecule with 5 bond pairs and 0 lone pairs and give the bond angle

A

trigonal bypyramidal 120° & 90°

29
Q

name the shape of a molecule with 6 bond pairs and 0 lone pairs and give the bond angle

A

octahedral 90°

30
Q

name the shape of a molecule with 2 bond pairs and 1 lone pair and give the bond angle

A

bent 118°-119°

31
Q

name the shape of a molecule with 4 bond pairs and 1 lone pair and give the bond angle

A

distorted 89° & 119°

32
Q

name the shape of a molecule with 3 bond pairs and 2 lone pairs and give the bond angle

A

t-shaped 89°

33
Q

name the shape of a molecule with 2 bond pairs and 3 lone pairs and give the bond angle

A

linear 180°

34
Q

name the shape of a molecule with 5 bond pairs and 1 lone pair and give the bond angle

A

square pyramidal 89° & 90°

35
Q

name the shape of a molecule with 4 bond pairs and 2 lone pairs and give the bond angle

A

square planar 90°

36
Q

give the workings out for how to work out the shape

A

group of central atom + no. of atoms around central atom = x
x + charge of compound = y
y / 2 = z
z - no. of atoms around central atom = no. of lone pairs

37
Q

give the four elements that are exceptions when trying to find out the shape of a compound

A

when combined with oxygen nitrogen, carbon, sulphur and chlorine will need to be drawn via dot and cross diagram to work out the shape

38
Q

electronegativity is …

A

the relative tendency of an atom in a covalent bone in a molecule to attract electrons in a covalent bond to itself

39
Q

name two reasons electronegativity increases or decreases and explain why

A
  • number of protons increase so atomic radius increases and electrons in the same shell are pulled in more
  • decreases down the group as distance between the nucleus and outer electrons so shielding of inner shell electrons increases
40
Q

name the four most electronegative atoms from lowest to highest

A

N & Cl
O
F

41
Q

name the three types of intermolecular force

A
  • induced dipole-dipole / london force
  • permanent dipole-dipole
  • hydrogen bonding
42
Q

explain why induced dipole-dipole is formed

A

• electrons are moving constantly and randomly causing electron density to fluctuate and some of the molecules to become more or less negative to form dipoles that can cause dipoles to form in neighbouring molecules

43
Q

explain the effect of increasing electrons on boiling points

A

the more electrons the higher the chance temporary dipoles will form so the induced dipole-dipole interactions are stronger between molecules so boiling point increases

44
Q

how do you predict the bond angle of C, S, N and Cl with oxygen

A

draw a dot and cross diagram

Chemistry A-Level OCR (28 decks)

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