Unit 1 Flashcards
1
Q
Steps to Reacting Masses Calculations
A
Identify two chemicals and write mole statement, convert moles to GFM and use proportion to calculate answer
2
Q
Reaction rates can be ______ by chemists
A
Controlled
3
Q
Rates of reaction can be affected by changes in…
A
Pressure, Particle Size, Temperature, Catalysts and Concentration
4
Q
If reaction rates are too low a manufacturing process will not be ______
A
Economically Viable
5
Q
If reaction rates are too high there’s a high risk of _____
A
Thermal Explosion
6
Q
Where’s a reactions rate the quickest and why?
A
At the start of the reaction and as there’s the highest concentration of reactants
7
Q
Calculating Average Rate
A
Change in concentration or mass or volume/ Time OR 1/Time
8
Q
Collision Theory
A
States that reactants must collide with correct geometry and posses a minimum energy (Activation Energy) before a successful reaction occurs
9
Q
In a dilute solution, particles are __A__ apart, meaning ___B___ likely to collide and react
A
A= Further B= Less
10
Q
In a concentrated solution, ___A___ particles are present in the same volume. They are __B__ likely to meet and react
A
A = More B = More
11
Q
(Using the Collision Theory) Explain why increasing the concentration increases the rate
A
It increases the number of particles, meaning more successful collisions
12
Q
(Using the Collision Theory) Explain why increasing the pressure of a gas increases the rate
A
This increases the concentration of the gas, meaning more successful collisions
13
Q
(Using the Collision Theory) Explain why decreasing the particle size increases the rate
A
This increases the surface area of the reactant, meaning more successful collisions
14
Q
Temperature
A
A measure of the average kinetic energy of the particles of a substance
15
Q
Why does a 10 Degree rise in temperate double a reaction?
A
The average kinetic energy of the colliding particles increases. Meaning more particles collide with >/= Activation energy. Resulting in more successful collisions
16
Q
Kinetic Energy
A
Movement
17
Q
Catalysts
A
Increase the rate of a reaction by providing an alternative pathway with a lower activation energy
18
Q
Temperate is a __A__ of the average __B__ of the particles of a substance
A
A= Measure B= Kinetic Energy
19
Q
The activation energy is the __A__ energy required by __B__ before the reaction will occur
A
A= Minimum Energy B= Colliding Particles
20
Q
What can be used to explain the effect of changing temperature on the kinetic energy of particles?
A
An energy distribution diagram
21
Q
Potential energy diagrams show the __A__ change that occurs in a reaction and the __B__
A
A= Enthalpy B= Activation energy
22
Q
Catalysts __A__ up a reaction by __B__ the activation energy
A
A= Speed B= Lowering
23
Q
Activated Complex
A
High energy with a unstable arrangement of atoms
24
Q
Where’s the activated complex located?
A
Top of the activation energy barrier
25
Two types of catalysts
Heterogeneous and Homogeneous
26
Heterogeneous Catalysts
Catalysts that exist in a different state to the reactants
27
Homogeneous Catalysts
Catalysts that exist in the same state to the reactants
28
Exothermic reactions have a __A__ change as the products have __B__ energy as the reactants
```
A= Negative Enthalpy
B= Less
```
29
Endothermic reactions have a __A__ change as the products have __B__ energy as the reactants
```
A= Positive Enthalpy
B= More
```
30
To find Enthalpy change
Energy of products - Energy of reactants
31
To find Activation Energy
Activation Energy - Energy of Reactants
32
What happens when a catalyst is added to a reaction (According to potential energy diagrams)
Enthalpy stays the same, Activation energy is lowered
33
Elements are arranged in order of ...
Increasing atomic mass and number
34
Periodicity
The regular recurrence of similar properties when elements are arranged in order of increasing atomic number
35
Explain what happens to the pattern in atomic size going across a period
The covalent atomic radius decreases because the nuclear charge increases, attracting the outer electrons more strongly, pulling them closer without any additional shielding.
36
Shielding
The electrons shells between the outer shell and the nucleus "Shield" (The outer electron from the nuclear charge)
37
Explain the pattern in atomic size going down a group
The covalent radius increases (atoms get larger) because of the addition of extra electron shells
38
First ionisation energy
The energy required to remove one mole of electrons from one mole of atoms in the gaseous state
39
Second ionisation energy
The energy required to remove one mole of electrons from one mole of 1+ ions in the gaseous state
40
The ____ group has the higher 1st ionisation energy
Noble gases
41
The ___ group has the lowest 1st ionisation energy
Alkali Metals
42
As you go across each period the ionisation energy ____
Increases
43
Why does the 1st ionisation energy increases going across a period?
Nuclear charge increases, attracting the outer electrons more strongly, meaning more energy is needed to remove the outer electron.
44
As you go down a group the first ionisation energy ____
Decreases
45
Why does the 1st ionisation energy decreases going down a group?
The energy level is further away so the electron is attached to it more strongly, meaning less energy to remove it and the outer electrons are more shielded from the nucleus
46
Why does the ionisation energy increases as more electrons are removed from an element?
Because of the larger attraction of the nucleus for the remaining electrons
47
Electronegativity
A measure of the attraction of an atom for the electrons in a bond
48
Across a period the electronegativity _____
Increases
49
Looking down a group the electronegativity _____
Decreases
50
Why is there no electronegativity value for the Noble gases?
They don't form bonds
51
Intramolecular Bonds
Bonds formed between atoms to get a full outer shell
52
Main types of intramolecular bonds
Metallic, Ionic, Covalent (Network and Discrete)
53
Only ____ group can't form intramolecular bonds
The noble gases
54
Structure of Metallic Bonds
Giant metallic lattice of positive ions in a sea of delocalised outer electrons
55
Delocalised
Free to Move
56
Definition of Metallic Bonds
Electrostatic attraction between positive ions and delocalised outer electrons
57
Metallic bonds are found in ....
Liquid and Solid Metals
58
Strength of Metallic Bonds
Varies but mostly strong
59
Metallic bonds get __A__ as you go down a group because the electrons are __B__ from the nuclear charge and are __C__ strongly attracted
```
A= Weaker
B= Further
C= Less
```
60
Properties of Metallic Bonds
- Conducts electricity because delocalised electrons are free to move
- Most have high mpts and bpts due to strong metallic bonds
61
Structure of ionic bonds
Lattice of positive and negative ions
62
Definition of ionic Bonds
The electrostatic attraction between positive and negative ions
63
Ionic bonds are found in....
Compounds containing metal/ammonium and a non-metal
64
Strength of Ionic bonds
Very strong bonds leading to high mpts and bpts
65
Properties of ionic bonds
- Conducts when molten in 'aq' solution as the ions are free to move
- Soluble in water
66
The formula of ionic bonds
Ratio of -
| 1 grain of salt : 2+ and negative ions
67
Structure of covalent network bonds
A giant lattice of covalently bonded atoms
68
Diamond is a covalent network bond. Properties:
Very Hard
69
Graphite is also a covalent network bond. Properties:
Weak forces between the layers make it soft and flaky
70
Properties of covalent network bonds
- Used as abrasives as they're very hard
- Most are non-conductors (Except graphite)
- Very high mpts and bpts
71
Only three elements with covalent network structures
- Boron
- Carbon(Graphite and Diamond)
- Silicon(Silicon Carbide and Silicon Dioxide)
72
Structure of Covalent Discrete Bonds
Discrete molecules held together by weak intermolecular forces
73
Most covalent substances are made up of covalent __A__ molecules. These can be compounds involving __B__
```
A= Discrete
B= Non- Metals
```
74
Discrete
There is a definite number of atoms bonded together in a molecule
75
Properties of a covalent discrete bond
- Low mpt and bpt
| - Non-Conductor
76
Ionic Character
The greater the difference int he electronegativity, the more ionic character it has
77
Pure covalent bond
The electronegativities of both atoms are identical and the bonding electrons are shared equally between both atoms.
78
Polar Covalent Bonds
When there is small difference between the electronegativites of both non-metal atoms in the covalent bond
79
Order of ionic character between pure covalent bonds, ionic bonds and polar covalent bonds
Pure covalent bonds, polar covalent bonds and ionic character.
80
The three Van Der Waals Forces
- Ldf Forces
- Permanent dipole-Permanent dipole interactions
- Hydrogen Bonding
81
London Dispersion forces
The result of electrostatic attraction between temporary dipoles and induced dipoles and are caused by the continual movement of electrons in atoms and molecules
82
How ldf arise
- The electron cloud around the molecule or atom won't be symmetrical. Meaning a more negative charge on one side of a molecule giving it a temporary dipole
- This dipole then induces dipoles in neighbouring molecules or atoms. The small positive end attracts to the small negative end of the induced dipole
83
Ldf are the only bond found between __A__. Polar molecules can have __B__ intermolecular forces between them.
```
A= Non- Polar Molecules
B= Additional
```
84
Ldf are _____ than covalent bonds
Weaker
85
Why is it that the larger the molecule of atom, the stronger the ldf?
The electron cloud is larger and has a higher number of temporary dipoles available to induce dipoles in neighbouring molecules or atoms
86
The higher the ldf, the ___ the boiling point
Higher
87
As you go down group 7, the molecule __A__ and the strength of the ldf __B__
A & B= Increases
88
Permanent dipole - permanent dipole interactions
Additional electrostatic forces of attraction between polar molecules
89
To find out if a molecule has permanent dipole-permanent dipole interactions
- Use electronegativities to see whether they are pure or polar covalent
- Work out the GFM
90
Hydrogen Bonds
Intermolecular forces which are formed between molecules in which hydrogen is bonded to a strongly electronegative atom like fluorine, oxygen or nitrogen
91
When hydrogen bonds are present, the substance will have a __A__ mpt and bpt than another substance of __B__ mass
```
A= Higher
B= Similar
```
92
Hydrogen bonds are the ___ intermolecular bond
Strongest
93
Properties of water that are affected by hydrogen bonding
- High mpt and bpt
- Surface tension
- It's more viscous than ethanol
- Water is miscible with methanol but immiscible with tetrachloromethane
- The density of ice is less than water at low temperatures
- Water is less volatile
94
Why is there high mpts and bpts in water
There's a lot of strong hydrogen bonds between the molecules and must be broken before ice can melt and water can boil
95
Why has water got surface tension
Because of hydrogen bonds
96
Why is water more viscous than ethanol
As it has more hydrogen bonds between the molecules
97
Surface tension
Acts as if it's surface is encloses in an elastic skin
98
Viscous
It's molecules can't flow over one another as easily, making it thicker
99
As the number of O-H groups increases, the amount of hydrogen bonds __A__ and the viscosity __B__
A & B = Increases
100
Miscible
Mixes
101
Immiscible
Doesn't mix
102
Why is water more miscible with methanol than with tetrachloromethane?
It has the same type of intermolecular forces
103
Water is _____ with liquids with weak intermolecular forces
Immiscible
104
What type of liquid would be miscible with tetracholoromethane?
Another non-polar covalent molecule
105
Why does ice float on water?
Ice is less dense than water because in ice the water molecules form an open lattice structure held together by lots of hydrogen bonds
106
Why is water less volatile than ethanol?
Water forms more hydrogen bonds, meaning more energy is needed for the molecules to separate
107
Volatile
Evaporates less easily
108
What molecules or compounds dissolve best in polar solvents like water and alcohols?
- Ionic compounds
| - Polar Molecules
109
What dissolves best in non-polar solvents?
Non-polar compounds
110
What needs to happen for a solute to dissolve in a solvent?
Enough energy must be releases when new bonds form between the solvent and solute to break the bonds between the solute particles
111
How are all acids formed
By dissolving polar covalent molecules in water
112
Hydrogen Chloride (HCl) dissolves to form...
Hydrochloric Acid
113
Hydrogen Nitrate (HNO3) dissolves to form...
Nitric Acid
114
Hydrogen Sulphate (H2SO4) dissolves to form...
Sulphuric Acid
115
Why can an ionic compound dissolve in water
The attraction between the ions and the polar bonds in water molecules release enough energy to break up the ionic lattice
116
Why can a polar covalent compound dissolve in water?
The attraction between the polar molecule and water molecules release enough energy to break up the covalent bonds in the molecule
117
Why are ionic compounds insoluble in non-polar solvents?
The non-polar molecules mean they can't attract ions strongly to break up the ionic lattice
118
Why are non- polar substances insoluble in water?
There's no strong attraction between non-polar molecules and water, so there's not enough energy released to break the covalent bonds within it
119
Why are non- polar substances soluble in non-polar solvents?
When new ldf form between the two molecules, enough energy is released to break the ldf between the non-polar substances
120
Elements with high mpt and bpt have....
Strong metallic or covalent (Network) bonds
121
Elements with low mpt and bpt have...
Ldf
122
In general the mpt and bpt of elements __A__ across period 2 and 3 reaching a __B__ at group 4
```
A= Increases
B= Peak
```
123
Why does the metallic bonds increases going across a period?
- The charge of the ion increases
| - The number of outer electrons which become delocalised increases
124
What happens to the mpt and bpt in Group 4?
It has the highest mpt and bpt because lots of covalent bonds have to be broken when it melts or boils
125
Why is H and He in period 1 and elements in group 5 to 0 have low mpt and bpt?
- In group 0, weak ldf must be broken between the atoms
| - H2, Group 5,6, and 7 elements must have broke ldf between the molecules
126
Explain the mpt and bpt going down group 1
It decreases because the metallic bonds get weaker
127
Explain the mpt and bpt as you go down group 7
The mpt and bpt increase because the molecules get larger, increasing the surface area and strength of ldf
128
Sublime
They change directly from a solid into a gas
129
Which elements are in sublime
Carbon and Arsenic
