Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry A Level > Bonding and Structure > Flashcards

Bonding and Structure Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

In the process of bonding…

A

… electrons move from a higher energy level to a lower energy level to form a more stable structure; achieved by a transfer or a sharing of electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do sections of the periodic table hold their valence electrons?

A
  • metals hold their valence electrons weakly
  • non-metals have a strong pull on their valence electrons

Therefore, there is a tendency for metal atoms to transfer electrons to jon-metal atoms, forming an électropositive metal ion and ah electronegative non-metal ion in a stable octet structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Electron density maps

A
  • found by deflecting X-rays off solids, causing X-day diffraction
  • show lines which represent areas of equal electron density
  • the cation can distort the electric field of the anion, turning the outer circles more square
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Strength of the ionic bonding depends upon

A

Charge density

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Charge density depends upon

A
  • charge of the ion

* radius of the ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Ionic radius going down a group

A
  • ions have the same charge
  • atoms become larger; so too do ions
  • ionic radius increases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Isoélectronic ions

A
  • ions that have the same number of electrons

* ionic radius is determined by nuclear charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Physical properties as evidence for ions

A
  • high melting and boiling points indicate strong electrostatic attraction between oppositely charged ions in ionic compounds
  • ability to conduct when aqueous or molten indicates the presence of mobile, charge-carrying particles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Electrolysis as evidence for ions - set up

A
  • shows ion migration
  • soak a rectangle of filter paper in water
  • place on a slide
  • connect électrodes and power pack
  • place à crystal of ionic material between electrodes o
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Electrolysis as evidence for ions - potassium manganate (VII)

A
  • potassium ions are colourless
  • manganate(VII) ions are purple
  • purple colour shoes negative manganate(VII) ions migrate towards positive electrode
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Electrolysis as evidence for ions - copper (II) chromate

A
  • copper (II) ions are blue
  • chromate (VI) ions are yellow
  • blue colour shows the positive copper(II) ions migrate towards the negative electrode
  • yellow colour shows negative chromate (VI) ions migrate towards positive electrode
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Bonding pair

A
  • the pair of electrons which are shared between electron deficient atoms to form molecules
  • can form simple molecules, polymers or giant molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Covalent bonding

A
  • short covalent bond means electron pairs are closer to nucleus; stronger
  • higher bond energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Bond energy

A
  • measure of how strong a bond is

* amount of energy given out as a bond forms/ amount of energy required to break a bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Sigma bond

A
  • lies directly between two atoms
  • symmetrically on the axis, joining the two nuclei
  • overlap is end-on; large
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Pi bond

A
  • forms when a double bond is present
  • forms alongside the atoms in two halves
  • overlap is parallèl; small
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Expansion of the octet

A
  • the octet is not the only stable molecular structure
  • atoms in period 3 and greater can increase the number of single electrons (number of covalent bonds to can form) by splitting a lone electron pair
  • splitting an electron pair costs energy because an electron is being promoted to the d sub-shell (higher energy level)
  • elements in period 2 can never have an oxidation level higher than 2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Dative covalent bonding

A
  • aka co-ordinate bonding
  • electrostatic attraction between the protons in the nuclei and the shared pair of electrons between them, both of these electrons having come from one atom
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Shapes of molecules

A
  • depends on electronic structure

* valence e-s girl bonds which determine molecular shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Electrons take up positions to…

A

… minimise répulsion between them; electron pair repulsion theory

Lone pairs have a greater repulsion than bonding pairs
Pushes the binding pairs closer together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Linear

A
  • 180°
  • 2 bonding pairs
  • 0 lone pairs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Trigonal planar

A
  • 120°
  • 3 bonding pairs
  • 0 lone pairs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Tetrahedral

A
  • 109.5°
  • 4 bonding pairs
  • 0 lone pairs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Trigonal pyramidal

A
  • 107.5
  • 3 bonding pairs
  • 1 lone pair
25
Q

Trigonal bipyramidal

A
  • 90°, 120°
  • 5 bonding pairs
  • 0 lone pairs
  • caused by expansion of the octet
26
Q

Octahedral

A
  • 90°
  • 6 bonding pairs
  • 0 lone pairs
  • caused by expansion of the octet
27
Q

Bent

A
  • 104.5°
  • 2 bindings pairs
  • 2/1 lone pair(s)
28
Q

Electronegativity

A

The ability of an atom with a covalent bind mind to attract the bonding pair of electrons

29
Q

Perfect covalent bond

A
  • bonding electron region is shared equally by each atom
  • atoms have same electronegativity
  • e.g. O2, Br2, N2
30
Q

Distorted covalent bond

A
  • in most molecules, one atom has a greater electronegativity
  • distorts electron region; polarisation
  • depends on the difference in electronegativity
31
Q

Polarisation

A
  • causes the region surrounding the more electronegative atom to become partially negative; creates a polar bond
  • δ+ / δ-
32
Q

Intermediate bonding

A

• when a covalent molecule has a polar bond, it gains ionic character

33
Q

Electronegativity values…

A

give an approximation of the predominant bonding type in a binary compound; type of bonding is a continuum

34
Q

Polarity

A
  • the presence of a polar bond may or may not lead to the formation of a polar molecule; it depends on the location of the charge centres
  • if there is no separation of charge (they are in the same place), the molecule is not polar
35
Q

Deflecting jets are used to…

A

… test of a molecule is polar

36
Q

Cyclohexane as a deflecting jet

A

Does not deflect the jet from the burette nozzle because it is not polar, so it does not interact with the charged polythene

37
Q

Propanone or ethanol as a deflecting jet

A

Because oxygen is electronegative, there is a dipole, causes δ+ carbon to be attracted to he negative polythene rod, deflecting the jet towards the rod

38
Q

Dipole

A

The separation of charge that exists in a polar molecule

39
Q

Dipole-dipole attractions

A

In polar materials, the positive charge in one molecule is attracted to the negative charge in another

40
Q

London forces

A
  • aka Van der Waals’, dispersion, idids
  • v. weak, become larger in larger molecules
  • increase as molecular mass increases due to greater chance of electron imbalance
  • present in all molecules
  • arise from electron imbalance due to the constant movement of e-s in atoms and molecules
  • the region to the atom or molecule at an instant where there is more electrons develops δ-
  • thus causes repulsion to electrons in the adjacent atom or molecule; inducing a dipole
41
Q

Noble gases

A

As molecular mass increases, so does boiling point, because the string London forces means molecules are harder to separate

42
Q

Hydrogen bonding

A
  • strongest
  • occurs when hydrogen is directly bonded to N, O or F
  • occurs because hydrogen shares its only electron in covalent bonding; high electronegativity draws the electron pair away, exposing hydrogen proton
  • lone pairs in N, O and F are attracted to this proton
  • 180° to minimise repulsion to electron pairs in hydrogen and covalent bonds
43
Q

Boiling points of alkanes

A
  • increase with molecular mass due to increased idids
  • inductive effect of idids increases with proximity; the closer the molecules can get, the stronger the force
  • branching decreases induction by decreasing possible contact area, lowering BO
44
Q

Water’s hydrogen bonding

A
  • can form 2 hydrogen bonds per molecule; melting and boiling points are high relative to molecular mass
  • during freezing, hydrogen bonds pull water molecules into fixed positions in a comparatively open lattice; ice is less dense than water -> it floats
  • entropy is low
  • Ice slows down the freezing process via insulation
45
Q

Solubility

A

A solvent will dissolve a substance that contains similar intermolecular forces

46
Q

Ionic compound solubility

A
  • water molecules are highly polar, and are therefore attracted to the ions
  • Oδ- in water is attracted to cations, Hδ+ is attracted to anions
  • hydration of ions
  • due to the vibration of water molecules, they shake the ions free from the lattice as they bind
  • some do not dissolve because the electrostatic attraction between the ions is too great for the water molecules to overcome
47
Q

Hydration of ions

A

Water molecules linking to ions

48
Q

Organic compound solubility

A
  • alcohols can form hydrogen bonds -> soluble
  • organic compounds that cannot form hydrogen bonds with water are insoluble
  • no interaction between hydrogen bonds within water have too strong an attraction
49
Q

Dissolving

A

Molecules of dissolving substance to intersperse themselves between solvent molecules

50
Q

Non-aqueous solvents

A
  • non-polar solvents dissolve non-polar materials

* allows easily interaction and therefore solubility

51
Q

Delocalised electrons region

A

Visualise as a cloud

52
Q

Malleability, ductility

A

Absence of fixed bonds allows ions to move; layers slide

53
Q

Factors affecting strength of metallic bonding

A

1) more valence electrons = stronger bonding

2) smaller metal ion = stronger bonding

54
Q

Why does having more valence electrons increase the strength of metallic bonding?

A
  • higher charge on the cations
  • higher charge density
  • higher charge in the electron field
  • electrostatic attraction increases
55
Q

Why does having a smaller metal ion increase the strength of metallic bonding?

A
  • charge density of cation increases

* electrostatic attraction increases

56
Q

More valence electrons =

A

Better conductivity

57
Q

Diamond

A
  • each C is connected to 4 other Cs
  • tetrahedral units
  • strong covalent bonds; high MP, BP and SP
  • hardest natural substance; drills
  • non-conductor (all e-s are taken up)
58
Q

Graphite

A
  • each C is connected to 3 other Cs (3 of 4e-s taken up)
  • remaining electron is delocalised; conductor
  • bond angles are 120°; hexagonal arrangement that joins in a plane to form a sheet
  • later structure is held together by idids
  • covalent bonds give high MP, BP and SP
  • malleable, solid lubricant
  • can be used in electrolysis; inert conductor
59
Q

Graphène

A
  • 200x stronger than steel
  • one atom thick (single hexagonal layer) -> 2D
  • most conductive material
  • stretchable, transparent, impermeable, flexible, strong
  • used for lightweight aircraft material, touch-screens

Chemistry A Level (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions