Foundations In Chemistry 2 Flashcards

1
Q

What is first ionisation energy

A

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ atoms

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2
Q

Factors affecting ionisation energy

A

Atomic radius, greater the atomic radius, smaller the nuclear attraction
Nuclear charge, greater nuclear charge, greater attraction
Electron shielding, repulsion of outer electrons by inner electrons ( more inner shells= greater shielding effect)

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3
Q

What is an atomic orbital

A

Electrons inhibit regions of space known as orbitals

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4
Q

What is the heinsenburg uncertainty principle

A

You cannot know with certainty both where an electron is and where its going next
It is impossible to define with absolute precision, at the same time, both the position and the momentum of an electron

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5
Q

What orbitals are available at the first energy level

A

1s orbital

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6
Q

What orbitals are available at the second energy level

A

2p , 2s

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7
Q

How many electrons are in each orbital

A

2

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8
Q

What is the aufbau principle

A

Electrons fill low energy orbitals before they fill higher energy ones

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9
Q

What is a shell

A

A group of atomic orbitals with the same principle quantum number , n

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10
Q

What is ionic bonding

A

The electrostatic attraction between positive and negative ions

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11
Q

What is electronegativity?

A

The ability of an atom to attract the pair of electrons in a covalent bond

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12
Q

What happens when two atoms have the same electronegativity

A

The pair of electrons in the covalent bond are equally attracted to the nuclei

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13
Q

What happens when one atom is more electronegative than the other ?

A

the electron pair in the covalent bond are close to the more electronegative atoms nucleus

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14
Q

What is the most electronegative element?

A

FLUORINE

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15
Q

What 3 factors does electronegativity depend on?

A
  1. Size of the positive charge on the nucleus
  2. Atomic radius
  3. Shielding of the nucleus by electrons in inner shells
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16
Q

How does electronegativity depend on the size of the positive charge on the nucleus?

A

moving left to right across the period, the number of protons in the nucleus increases
increased positive charge increases the attraction between the nucleus and the pair of electrons in the covalent bond

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17
Q

How does electronegativity depend on atomic radius?

A

Smaller the atomic radius, the closer the bonding electrons will be to the nucleus of the atom
As we move from down to up across periods the atomic radius increases
As we move across groups the atomic radius decreases

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18
Q

How does the shielding of the nucleus by electrons in inner shells effect electronegativity?

A

electrons in inner shells screen electrons in the outer shell from the positive charge of the nucleus
Greater number of electrons= lower in electronegativity

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19
Q

What is a dipole?

A

When an electron pairs much closer to one atom than the other, the separation of charge is called a dipole .
The separation of charge is then called a polar covalent bond.

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20
Q

What are intermolecular forces

A

Weak forces that act between molecules

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21
Q

What are the three types of intermolecular forces?

A

Induced dipole- dipole interactions
Permanent dipole- dipole interactions
Hydrogen bonds

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22
Q

What are induced dipole dipole interactions?

A

Dipoles that are induced from an instantaneous dipole where their is random movements of electrons, causing there to be a slight negative charge on one side compared to the other

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23
Q

What does the strength of London forces depend on?

A

Number of electrons

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24
Q

What is a permant dipole?

A

Where two atoms that are bonded have different electronegativities, a polar bond forms. The more electronegative atom draws more of the negative that he towards itself and away the other atom .

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25
Q

Examples of giant covalent structures

A

Diamond
Graphene
Graphite

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26
Q

Diamond structure and properties

A

-atoms arranged in a tetrahedral structure
- bond angle of 109.5
-large melting and boiling points due to the large amount of energy required to break the covalent bonds
-does not conduct electricity, every electron is in a covalent bond
-insoluble, solvents cannot disrupt the large number of strong covalent bonds

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27
Q

Graphite structure and properties

A

-carbon atoms form only 3 bonds, delocalised electrons
-bond angle of 120
-delocalised electrons act as mobile charge carriers
-good conductor of electricity

28
Q

Graphene structure and properties

A

-single layer of graphite
-slippery
-also delocalised electrons
-thin sheets
-good conductor of electricity

29
Q

What is hydrogen bonding

A

When the lone electrons are attracted to the slightly positive atom

30
Q

What is the strongest type of intermolecular force.

A

Hydrogen bonds

31
Q

What are 2 conditions of hydrogen bonding

A
  • hydrogen atom bonded to a strongly electronegative element
  • the electronegative atom must have at least one lone pair of electrons
32
Q

What is hydrogen bonding in water?

A
  • water molecules undergo hydrogen bonding
  • when we boil water, it takes a great deal of energy to break the hydrogen bonds
  • relatively high melting snd boiling points
  • solid ice is less dense than water
33
Q

Why is ice less dense than water

A

As we reach freezing point the water molecule arranges themselves into an ordered structure which is stabilised by the network of hydrogen bonds. In ice, the water molecules are further apart then in liquid water, making it less dense

34
Q

What happens to the atomic radius as you move across a period

A

It increases top to bottom, moving down a group
Number of electrons increases as you move down a group
Outer electron shell is further from the nucleus
Each element has one more full outer shell
Increases amount of shielding between the nucleus and outer electron
Less attraction between outer electron and nucleus

35
Q

How does atomic radius differ from across the periods (left to right)

A

Decreases
Each element has one more proton in its nucleus than the element before.
Positive charge increases across the period, increased attraction between the nucleus and electrons
- draws the electrons closer to the nucleus, causes the atomic radius to decrease across the group

36
Q

What is first ionisation energy

A

Energy needed to remove one mole of electrons from one mole of gaseous atoms to from one mole of gaseous 1+ ions

37
Q

Why does first ionisation energy increases across the as we move across a period?

A

The positive charge in the nucleus increases, as the number of protons increases
The increases the attraction between the nucleus and the electrons
Atomic radius decreases across a period
Both the increased nuclear charge and the decreases atomic radius mean the outer electrons are more attracted to the nucleus

38
Q

Why does ionisation energy decrease as we go down a group?

A

Atomic radius decreases
-outer electrons shell are further away from the nucleus
Number of internal electron shells increases
- there is more shielding between the nucleus and the outer electrons

39
Q

What is metallic bonding

A

Negative delocalised electrons ate strongly attracted to the positive cations by electrostatic attraction

40
Q

What are the key features of giant metallic lattice

A

Cations are fixed in place

Delocalised electrons are free to move, can conduct electricity in solids and liquids
Relatively high melting and boiling points
Delocalised electrons have a strong attraction to cations, requires a lot of energy to overcome
Do not dissolve
Brittle

41
Q

What is the principle quantum number

A

The number each shell is given
Example, first shell has a principe quantum number of 1

42
Q

How to work out maximum number of electrons

A

2n2

43
Q

What are atomic orbitals

A

A region around the nucleus that can hold up to 2 electrons with opposite spins

44
Q

What is an electron

A

A cloud of negative charge

45
Q

What are the different types if atomic orbitals

A

S
P
D
F

46
Q

What shape is the s orbital

A

Spherical

47
Q

What shape is the p orbital

A

Dumb bell

48
Q

What are the rules of electron configuration

A

Orbitals with the lowest energies are filled first
Can have up to 2 electrons in the same orbital but must have opposite spins
Orbitals with the same orbital, individually fill first with electrons then pair . Electrons in the same orbital repel

49
Q

When is the 3d sub shell more stable

A

When it is half full or completely full

50
Q

What is electron repulsion theory

A

Pairs of electrons repel all the outer shells
Electron pairs now move as far apart as possible to minimise repulsion

51
Q

How are shapes of molecules determined

A

Electrons pairs surrounding central atom

52
Q

Liner molecule

A

Bond angle of 180
0 lone pairs
2 bonding pairs

53
Q

Tetrahedral molecule

A

Bond angle of 109.5
0 lone pairs
4 bonding pairs

54
Q

Trigonal planar

A

Bond angle of 120
0 lone pairs
3 bonding pairs

55
Q

Trigonal bipyramidal

A

Bond angle of 120 / 90
0 lone pairs
5 bonding pairs

56
Q

Octahedral

A

Bond angle of 90
0 lone pairs
6 bonding pairs

57
Q

How much do you decrease a bond angle by with each lone pair

A

2.5 degrees, lone pairs repel more strongly than bonding pairs

58
Q

Name all the shapes of molecules that have 0 lone pairs

A

Linear molecule
Octahedral
Trigonal planar
Trigonal bipyramidal
Tetrahedral

59
Q

Pyramidal

A

Bond angle of 107
1 lone pair
3 bonding pairs

60
Q

Non linear

A

Bond angle of 104.5
2 lone pairs
2 bonding pairs

61
Q

Name the only 2 shapes of molecules that have lone pairs

A

Pyramidal
Non linear

62
Q

What is covalent bonding

A

When a non metal reacts with a metal creating a shared pair of electrons

63
Q

What are lone pairs

A

Any electrons that are not user to form a covalent bond

64
Q

What is a dative bond

A

When an ion no longer has electrons to share so teh atom it is attempting to share with uses its lone pair of electrons to form a covalent bond

65
Q

What are the two main points about dative bonds

A

In order for dative bonds to form, the acceptor atom must be electron deficient, must be available orbitals for the electron to occupy
Dative bonds are exactly the same as normal covalent bonds

66
Q

What are the properties of ionic bonding

A

Giant ionic lattice=
Every ion is attracted to every oppositely charged ion causing the electrostatic forces of attraction
Very high melting and boiling points
Tend to be soluble in polar solvents
Do not conduct electricity ehen solid
If charges on ion increase, solubility often decreases as the water molecules cannot overcome the electrostatic forces of attraction

67
Q

What is an ionic bond

A

Transfer of electrons from one metal to the non metal