Electrons, Bonding and Structure Flashcards
(100 cards)
1
Q
How many electrons can be in shell 1?
A
2
2
Q
How many electrons can be in shell 2?
A
8
3
Q
How many electrons can be in shell 3?
A
18
4
Q
How many electrons can be in shell 4?
A
32
5
Q
What is an electron shell?
A
Group of atomic orbitals with the same principle quantum number, n
6
Q
What is n (principle quantum number)?
A
A number representing the overall energy level of the orbital.
7
Q
What is an orbital?
A
A region of high probability within an atom that can hold up to 2 electrons with opposite spin
8
Q
What does it mean if n (principle quantum number) is bigger?
A
The bigger the number, the further the distance between the energy level and atomic nucleus
9
Q
How man electrons do orbitals hold?
A
2
10
Q
What must electrons in the same orbital have?
A
Opposite spin
11
Q
What are the 4 orbitals?
A
S-orbital
P-orbital
D-orbital
F-orbital
12
Q
Where is s-orbital present?
A
n=1 upwards
13
Q
Where is p-orbital present?
A
n=2 upwards
14
Q
Where is d-orbital present?
A
n=3 upwards
15
Q
Where is f-orbital present?
A
n=4 upwards
16
Q
How many s-orbitals does a shell contain?
A
1
17
Q
How many p-orbitals does a shell contain?
A
3
18
Q
How many d-orbitals does a shell contain?
A
5
19
Q
How many f-orbitals does a shell contain?
A
7
20
Q
What is the shape of a s-orbital?
A
Sphere
21
Q
What is the shape of a p-orbital?
A
Dumbbell
22
Q
What is the order that you fill orbitals?
A
1s 2s 2p 3s 3p 4s 3d 4p
23
Q
What are the two exceptions when it comes to filling orbitals?
A
Cu
Cr
24
Q
What does Cu do?
A
1s2 2s2 2p6 3s2 3p6 4s1 3d10
25
What does Cr do?
1s2 2s2 2p6 3s2 3p6 4s1 3d5
26
What do CU and Cr do this?
Because they can become stable from full and half full 3d sub shells
27
How can you shorten filling orbitals?
By using the noble gases
28
What are the three noble gases that you can use?
He 1s2
Ne 1s2 2s2 2p6
Ar 1s2 2s2 2p6 3s2 3p6
29
What is a lattice?
A regular repeated three dimensional arrangement of atoms, ions or molecules in a metal or other crystalline solid
30
What is ionic bonding?
Ions of opposite charge held together by electrostatic attraction
31
What is ionic bonding between?
Metal and non metal
32
What are the properties of ionic bonding?
High melting and boiling points
Can conduct in liquid/aqueous state but not in a solid state
Soluble in polar solvents
33
Why does it have high meting and boiling points?
Because a large amount of energy is needed to overcome strong electrostatic attraction
34
Why is the melting point higher in certain ionic bonds?
Greater ionic charge in lattice = higher melting point
35
What must happen for ionic bonds to dissolve in polar solvents?
Ionic lattice must be broken down
| Water molecules must attract and surround the lattice
36
What is an example of a polar solvent?
Water
37
What does solubility depend on in ionic bonding?
An attraction between the ions and water molecules
38
What happens as the ionic charge increases?
The solubility decreases
39
Why can ionic bonds conduct electricity when liquid or molten?
Because ions are free to move therefore there is charge carries so it can conduct electricity
40
Why can't sometimes ionic bonds be dissolved in water?
Because the ionic attraction is too strong
41
What is covalent bonding?
Atoms that share a pair of electrons held together by intermolecular forces
42
What is it called when a pair of electrons aren't shared with the other element?
Lone pair
43
What is it called when a covalent bond does that have a full amount of electrons?
Electron defieicent
44
What is an example of an electron deficient covalent bond?
Borontrifluoride BF3
45
What rule is broken when a covalent bond is electron deficient?
Octet rule
46
When is it okay for the octet rule to be broken?
When there is more than 8 electrons in the covalent bond because the 3rd shell can hold 18
47
What is a dative bond?
A bond formed when both electrons in the share are donated by one atom
48
What is an example of a dative bond?
When ammonia acts as a base and reacts with H+ so donates both its electrons to the H+ to form ammonium
49
When drawing covalent ions what do you represent the extra electron as?
A little triangle
50
What are the properties of covalent bonding?
Low melting and boiling points
Insoluble in polar solvents
Doesn't conduct electricity
51
Why does covalent bonds have a low melting and boiling points?
Small covalent molecules
| Weak intermolecular forces
52
Why are covalent bonds insoluble in polar solvents but are in non-polar solvents?
Because london forces form between the solvent and the molecules
53
Why does covalent bonds not conduct electricity?
Because there is no mobile charges so no charge carries so can't conduct
54
What is the VSEPR Theory?
The shape of a molecule/ion is determined by the no. of electron pairs in the outer shell of the central atom, repelling as far away as possible
55
What does VSEPR stand for?
```
Valence
Shell
Electron
Pair
Repulsion
```
56
What shape is formed when there is two regions?
Linear
57
What is the bond angle of a linear molecule?
180 degrees
58
What is the shape formed when there is three regions>/
Trigonal planar
59
What is the bond angle of a trigonal planar molecule?
120 degrees
60
What shape is formed when there is four regions?
Tetrahedron
61
What is the bond angle of a tetrahedron molecule?
109.5 degrees
62
What shape is formed when there is six regions?
Octahedron
63
What is the bond angle of an octahedron molecule?
90 degrees
64
What is the shape formed when there is 5 regions?
Trigonal bi-pyramid
65
What is the bond angles of a trigonal bi-pyramid?
90 and 120 degrees
66
What shape is formed when there is 3 bonding pairs and 1 lone pair?
Pyramidal
67
What shape would you think it would be there was 3 BP and 1 LP and why does this shape not form?
Tetrahedron as there is 4 electron pairs
| But the lone pair aren't attracted to the nuclei so they repel a further 2.5 degrees
68
What is the bond angle of a pyramidal molecule?
107 degrees
69
Why doe lone pairs have a greater repulsion?
Because there aren't attracted to the nuclei
70
How much does lone pairs reduce the bond angle by?
2.5 degrees
71
What shape is formed when there is 2 bonding pairs and 2 lone pairs?
Non-linear
72
What is the bond angle of a non-linear molecule?
104.5 degrees
73
What is electronegativity?
A measure of the tendency of an atom to attract a bonding pair of electrons within a covalent bond
74
What happens to electronegativity across a period?
It increases
75
Why does electronegativity increase across a period?
Nuclear charge increases so there is a greater nuclear attraction so electronegativity increases
76
What happens to electronegativity down a group?
It decreases
77
Why does electronegativity decrease down a group?
The size of the atom increases so shielding of the outer shell increases so nuclear attraction reduces so electronegativity decreases
78
What happens in a bond between different atoms when one element is more electronegative?
The electrons will attracts towards the more electronegative element
Will have a S- charge
79
What happens to the other element in the bond when the other is more electronegative?
It will lose a small amount of electron density
| Will have a S+ charge
80
What is S-?
A (slight charge) delta
81
When are molecules polar?
When the dipoles are in the same direction
82
When are molecules non-polar?
When dipoles are symmetrical (opposite direction) so they cancel each other out
83
What does it mean when there is no difference between electronegativity?
It is a non-polar covalent bond
84
What does it mean when there is a small difference between electronegativity?
It is a polar covalent bond
85
What does it mean when there is a large difference between electronegativity?
It is an ionic bond
86
What is the size of a small difference?
0-1.8
87
What is the size of a large difference?
>1.8
88
What are intra-molecular forces?
Strong bonds inside of molecules
89
What are intermolecular forces?
Forces that act between different molecules and are much weaker than covalent bonds
90
What are the three types of forces and their relative strength?
London forces - 1
Hydrogen forces - 50
Permanent dipole-dipole - 10
91
What is a dipole-dipole force?
A weak attractive force between permanent dipoles in neighbouring polar molecules
92
Where does dipole-dipole happen?
Attraction between two delta charges of elements
93
How do london forces work?
Moving electrons = changing dipole
Instantaneous dipole induces dipole on neighbouring molecule
Induced dipole induces further dipole
They attract each other
94
What happens to london forces as the no.of electrons increase?
Strength of london forces increase due to the larger instantaneous dipole created
95
What are the anomalous properties of water?
```
Elevated melting + boiling point
Ice floats (solid is less dense than the liquid)
```
96
Why does water have an elevated boiling + melting point?
Because of strong hydrogen bonds
97
Why does ice float?
Because when water freezes its molecules arrange themselves in a "more open, regular, lattice structure"
98
Where does the hydrogen bond form?
Between the S+ and S- of two dipoles
99
What are you doing when you're boiling/melting water?
Breaking the hydrogen bonds
100
When can hydrogen bonding only happen?
When hydrogen is covalently bonded to fluorine, nitrogen or oxygen
