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A level Chemistry > Chapter 5 - Electron Bonding & Structure > Flashcards

Chapter 5 - Electron Bonding & Structure Flashcards

1
Q

shells are regarded as

A

energy levels

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2
Q

the energy increases as

A

shell no. increases

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3
Q

what is the principal quantum no.

A

the shell no. or energy level number

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4
Q

equation of number of electrons in a shell?

A

2 n (^2)

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5
Q

what is an atomic orbital?

A

a region around a nucleus that can hold up to 2 electrons, with opposite spins

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6
Q

an atomic orbital can hold a maximum of

A

2 electrons

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7
Q

4 different types of orbital are?

A

s,p,d,f

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8
Q

s orbital

A
  • sharp
  • the shape of a sphere
  • each shell from n = 1 contains 1 s orbital
  • the greater the shell no, the greater the radius of the s orbital
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9
Q

p orbital

A
  • principal
    -dumb-bell shaped
  • there are 3 seperate p orbitals at right angels to each other - p p p
    x y z
  • each shell from n = 2 contains 3 p orbitals
  • the greater the shell no., the further the p orbital from the nucleus
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10
Q

d orbitals, f orbitals

A

diffuse, fundamental

  • each shell from n=3 contains 5 d orbitals
  • each shell from n = 4 contains 7 f orbitals
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11
Q

what is a sub shell?

A

within a shell, orbitals of the same type are grouped together as sub-shells

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12
Q

filling of orbitals rule

A

orbitals fill in order of increasing energy

note: 3d is a higher energy level than the 4s subshell, so 4s fills first

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13
Q

electrons pair with _____ spins

A

opposite

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14
Q

what is the point of opposite spins?

A

the opposite spins help counteract the repulsion between the negative charges of the 2 electrons

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15
Q

name of model used to show the electrons

A

electrons-in-box model

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16
Q

shorthand electron configurations

A

elec congigs can be expressed more simply in terms of the previous noble gas plus the outer electron sub shells

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17
Q

when forming ions,

A

the highest energy subshells lose or gain electrons

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18
Q

4s subshell fills before the 3d subshell but it also

A

empties before the 3d subshell

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19
Q

the Heisenberg uncertainty principle states that?

A

it is impossible to certainly say where an electron is and where it will be going

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20
Q

each sub shell is composed of how many types of orbitals?

A

only 1

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21
Q

Aufbau principles?

A
  • shells and subshells are filled according to a set no. of rules
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22
Q

how are electrons added?

A

1 by 1, the paired

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23
Q

Ar Equation

A

total of (% x mass no.)

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24
Q

special cases for electron config

A

Chromium (Cr) & Copper (Cu)

- electron moves from 4s orbital to 3d orbital reduces repulsion between electrons

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25
Q

What is an ionic bond?

A

strong Electrostatic attraction between positive and negative ions

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26
Q

Forming an ionic bond?

A
  • between metal & non metal

- elements seek to gain a full outer shell of electrons

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27
Q

Dot and cross diagrams show the _______ __ __________?

A

Origin of electrons

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28
Q

Ionic structures?

A
  • Exist in giant ionic lattices
  • each ion is surrounded in all directions
  • 3D lattice
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29
Q

Why do ionic substances have high melting and boiling points?

A
  • solid at room temp e.g. salt NaCl
  • because ionic bonds are strong electrostatic forces of attraction and so large amounys or energy are needed to break these bonds
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30
Q

What is a polar solvent?

A

A dolbeny which contains polar bonds

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31
Q

Ionic substances are soluble in?

A

Polar solvents e.g. water

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32
Q

Why do polar bonds occur?

A
  • are a result if the unequal distrubution of sharing of electrons within a bond
  • results in atoms having a slight charge
  • these slightly charged atoms can attract the charged ions within ionic lattices
  • the lattice becomes disrupted
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33
Q

Ionic substances - electrical conductivity?

A

They are electrolytes
When this happens the previously solid lattice breaks down and the ions are now free to move
- solid = ions fixed in place = no mobile chartge carriers
- liquid - lattice breaks down = ions free to move = mobile charge carriers

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34
Q

What is an electrolyte?

A

They can conduct electricity when melted or dissolved in water

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35
Q

Which 2 key factors determine the strength of an ionic bond?

A
  • charge on the ions

- distance between the ions

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36
Q

Ions with greater charges will have ….

A

Greater electrostatic attractions between them and so form stronger bonds

37
Q

Smaller ions…

A
  • Have a smaller internuclear distance, meaning the electrostatic force of attraction is stronger
    ➡️ smaller ions firm stronger ionic bonds in more closely packed lattices
38
Q

What is a covalent bond?

A

Strong electrostatic force of attraction between a shared pair of electrons and the nuclei of the bonded atoms

39
Q

Covalent bonds….

A

Occur between 2 non metals - e.g Cl 2

40
Q

Single covalent bond?

A
  • involves ONE shared pair of electrons

- e.g. Cl 2, H 2 O

41
Q

Multiple covalent bonding?

A

Involves more than 1 shared pair of electrons

  • e.g. O 2 - 2 shared pairs, double bond
  • e.g. - N 2 - 3 shared pairs - triple bond
42
Q

Dative covalent bond?

A
  • when both electrons in a bond are donated by the same atom.
  • equivalent to other covalent bonds
  • e.g NH 4
43
Q

Simple molecular substances?

A
  • Made up of small molecules
  • in solid state, exist as a lattice
  • simple molecules
  • within each molecule, the atoms are tightly held together by covalent bonds
  • weak intermolecular forces act betwern mols
44
Q

Properties of simple molecular substances?

M.p, B.P

A
  • Low - weak intermolecular forces of attraction between mols
  • small amount of energy needed to disrupt thse forces
45
Q

Simple molecular- solubility

A
  • soluble in non polar solvents
  • ‘like dissolves like’
  • weak intermolecular forces between molecules of non polar solvent are similar to that in simple molecular substances, ➡️ these forces these forces are able to act between the molecules of simple molecular substance and the solvent
46
Q

Simple molecular - conductivity

A
  • non conductors

- no charged particles are free to move and carry charge

47
Q

Giant covalent substances?

A
  • atoms are joined to adjacent atoms by strong covalent bonds
  • network of covalent bonds
  • giant lattice is formed
  • lots of covalsnt bonds throughout structure
  • e.g. diamond, graphite, silicon dioxide
48
Q

Giant covalent substances- M.P & B.P

A
  • strong covalent bonds exist throughout lattice

- lots of enerhy required to break thse bonds

49
Q

Giant covalent- solubility?

A
  • insoluble in polar & non polar solvents

- strong covalent bonds are not disrupted by either type of solvent

50
Q

Giant covalent - conductivity

A
  • non conductors- no charged particles that are free to move and carry current
  • EXCEPTION: GRAPHITE- between layers of the lattice, delocalised electrons r able to move , when voltage is applied these electrobs are free to move parallel to the layers
51
Q

The shape of a compound or ion is dictated by?

A
  • Number of electron pairs around the central atom

- the nature of these pairs- bonding or lone

52
Q

Electron pair repulsion- bonding pairs

A

Pairs of electrons that are involved in bonding

These repel each other equally

53
Q

Electron pair repulsion- lone pairs

A
  • pairs of electrons that are not involved in bonding
  • lone pairs repeal each other more than bonding pairs because thy are more elecrron dense
    ☆ each lone pair reduces the bond angle by about 2.5 °C
54
Q

The Octet rule?

A
  • through chemical bonding, elements usually achieve a noble gas configuration - a full outer shell
  • Octet rule suggests 8 electrons in pairs will exist in the full outer shell where 4 electrons form full outer shells
55
Q

Why is it not always possible to get 8 electrons in pairs in the outer shell?

A

There may be:

  • too few electrons to form an octet
  • more than enough electrons to form an octet
56
Q

Not enough electrons- shrinking the octet?

A
  • neither beryllium nor Boron have enough electrons to form an octet
  • the unpaired electrons will pair up
  • the element will not achieve an octet
57
Q

Expanding the octet

A
  • the bonding atom will have more than 8 electrons in its outer shell
  • can occur in group 15- 17, from period 3 downwards
58
Q

what is a covalent bond?

A

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

59
Q

diagrams for ionic bonding remember?

A
  • don’t need to show transfers
  • square brackets with charge
  • valence shell electrons only
60
Q

[ionic] the ions attract each other from all directions and form a ____ _____ ______

A

giant ionic lattice

61
Q

metallic bonding definition?

A

metallic bonding is the strong electrostatic attraction between the cations and delocalised electrons

62
Q

[metallic bonding] diagrams?

A
  • metal ATOMS are close enough for outer shells to overlap and electrons can move throughout the outer shells of all atoms
  • write charge on ion
  • particles NEED to be TOUCHING
63
Q

Why aren’t they metal ions?

A

electrons are delocalised, not lost so not an ion

64
Q

covalent bonding definition: atom?

A

smallest particle that makes up an element that can show the element’s chemistry. Contains protons, neutrons, electrons

65
Q

covalent bonding definition: electron?

A

a negatively charged subatomic particle with a relative mass of 1/1836 orbiting the nucleus in a shell.

66
Q

covalent bonding definition: nucleus?

A

structure at the centre of the atom with an overall positive charge that contains protons & neutrons.

67
Q

covalent bonding definition: : molecule?

A

a particle that has 2 or more non metal atoms bonded together covalent. Can be the same or different e.g. oxygen, CO2

68
Q

covalent bonding definition: Ion?

A

an atom or group of atoms that has lost or gained electrons to have a + or - charge

69
Q

covalent bonding definition: intermolecular forces

A

are BETWEEN molecules

- e.g. hydrogen bonds, permanent dipole forces or induced dipole forces

70
Q

covalent bonding definition: intramolecular forces

A

are WITHIN a molecule i.e. covalent bond

71
Q

dative covalent bonds involve?

A

ab lone pair of electrons and an empty orbital

72
Q

how are dative covalent bonds shown?

A

➡

73
Q

the average bond enthalpy is?

A
  • the average energy needed to break 1 mole of covalent bonds forming gaseous atoms
74
Q

s block ?

A

highest energy electrons in the s subshell

- left block of two groups

75
Q

p block?

A
  • highest energy electrons in the p subshell

- right block of 6 groups

76
Q

d block?

A
  • highest energy electrons in the d subshell

- centre blocks of 10 groups

77
Q

why does 4s empty before 3d as well?

A
  • energies of 4s and 3d subshells are very close together

- once filled, 3d energy level falls bellow 4s energy level

78
Q

which ionic structures not be very soluble (in polar substances)?

A
  • in a compound made of ions with large charges, the ionic attraction may be too strong for water to be able to break down the lattice structure.
79
Q

solubility requires which 2 main processes?

A
  • ionic lattice must be broken down - relative strngths of attractions within lattice
  • water molecules must attract and surround the ions
80
Q

summary of properties of ionic compounds?

A
  • high MP &BP
  • tend to dissolve in polar solvents such as H2O
  • only coduct in liquid state or aqueous solution
81
Q

a covalent bond is localised

A

acting solely between the shared pair of electrons and the nuclei of the 2 bonded atoms.

82
Q

expansion of the octet is only possible from?

A

the n=3 shell, where a d subshell becomes available for expansion

83
Q

dative covalent bond a.k,a

A

coordinate bond

84
Q

in a dative covalent bond, the shared pair was orginally a ?

A

lone pair of electrons on one of teh bonded atoms

85
Q

solubility of non polar simple molecular substances?

A

when in non polar solvent = intermolecular foces form between molecules & solvent
- the interactions weaken the IMF in the simple molecular lattice. the IMF break & compound dissolves

86
Q

non polar simple molecular substance solubility in polar solvents?

A
  • little interaction between molecules in lattice & solvent molecules
  • inter molecular bonding within the polar solvent is too strong to be broken
87
Q

solubility of polar simple molecular in polar solevents?

A
  • may dissolve in polar solvents
  • ## solubility depends on strength of dipole
88
Q

melting points of individual metals depends on?

A

no. of delocalised electrons per atom

- metals with more delocalised electrons will have a higher MP

89
Q

2 properties of metals?

A
  • malleability - metals can be hammered into different shapes
  • ductility - metals can be drawn out or stretched

A level Chemistry (39 decks)

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