Lecture 4 - The chemistry of life Flashcards
1
Q
What is matter
A
Occupies physical space and has a mass
Generally seen, smelled and felt - physical presence
Moved around by energy
2
Q
What 3 states does matter exist in
A
Solid
Liquid
Gas
3
Q
Solid
A
Definite shape and volume
Bones,teeth ( not much water, a lot of salts )
4
Q
Liquid
A
Definite volume, flows to fill space
Blood plasma
5
Q
Gas
A
No defined shape nor volume
Air we breath in and out
6
Q
What is energy
A
Ability to put matter into motion - capacity to do Work
- Tangible, no mass, does not take up space
- Form of movement
7
Q
Kinetic energy
A
Is that which moves things. From the constant movement of tiny bits of matter; atoms. To the movement of a bouncy ball.
e.g. bike moving up hill
8
Q
Potential energy
A
Stored energy. Inactive energy, that has potential to do work. When the energy is
released, it becomes kinetic energy.
e.g. stopped bike on top of hill
9
Q
What are the 4 forms of energy
A
- Chemical energy
- Electrical energy
- Mechanical energy
- Radiant energy
10
Q
What is chemical energy
A
Stored in chemical bonds between atoms in compound. Chemical reactions rearrange atoms. Energy in our bodies is stored as useful potential energy in ATP.
11
Q
What is electrical energy
A
Movement of charged particles through, or along cell membranes.
Nervous system - action potential
12
Q
What is mechanical energy
A
Energy directly involved in moving matter.
13
Q
What is radiant energy
A
Energy that travels in waves.
14
Q
Law of energy
A
Energy can neither be created nor destroyed
15
Q
Energy conversions
A
- With few exceptions, energy is easily converted between the different forms of energy.
- Need energy transfer to create something new = reactions
16
Q
How are energy conversions inefficient
A
Energy is always ‘lost’ to environment - this is heat ( from bond making )
It is only ‘lost’ from that system into another.
17
Q
Elements
A
- All matter is composed of elements
18
Q
Can elements be broken down into smaller substances
A
No
it is the smallest building block
19
Q
How many elements are there
A
118……
92 in nature
26 - in particle accelerator - smash elements together and see what they create
20
Q
What 4 elements make up most of our body weight
A
C , O , H , N
21
Q
What is each element composed of
A
An atom
22
Q
Size range of atoms
A
Smallest < 0.1nm
Largest ~0.5nm
23
Q
Physical properties of elements
A
Detected with sense ie colour, taste
Measurable ie boiling point
24
Q
Chemical properties of elements
A
How elements interact with
each other
25
Charge and mass of proton
positive
| 1
26
Charge and mass of neutron
neutral
| 1
27
Charge and mass of electron
Negative
| 1/1,840
28
What do electrons do and what does it allow
Orbit the nucleus
Spin on outside = allows it to interact with other things in environment
- Charge difference holds it together
29
What makes up nucleus
Protons and neutrons
30
Charge of nucleus
Positive
31
What are atoms charge
Electrically neutral = same number of protons and electrons
| i.e. 1 e- added = 1 proton also added
32
How do elements differ from each other
By number of protons, neutrons and electrons
33
What do the number of protons, neutrons and e-'s give rise to
Variation in chemical and physical properties of the elements.
34
What are isotopes
Structural variants of elements
| Electrons and protons remain constant in number. Different number of neutrons
35
What are radioisotopes
Isotopes formed from radioactivity e.g. C14
36
What is radioactivity
Atomic decay - releases forms of energy - mini explosion - destroys cells - radiation bad -energy source
37
Process of radioactivity
- Heavier variants of elements are unstable. ( because more neutrons than protons/e's
- Atoms will spontaneously decompose into stable forms.
- Process of atomic decay is radioactivity
38
What is the mini explosion and what is released
Atomic decay
- alpha particles (2p + 2n) - helium
- beta particles (electron-like particles)
- gamma rays (electromagnetic energy)
39
What happens to energy released during radioactive decay
Transformed into different element
40
What is molecule of element
When atoms of same element combine
41
What is molecule of compound
Different kinds of atom combine
42
How does neutrons affect atomic decay
More neutrons = more atomic weight
43
Do atoms exist in free state
Not usually
| They are often chemically combined with other atoms
44
Why form compounds or elements
To become stable
45
Why are atoms not in a free state
Unstable
46
What are mixtures
2+ components physically intermixed
| - Same matter, don't particularly interact
47
Where is most matter found
In mixtures
48
What are the 3 types of mixtures
- Solutions
- Colloids
- Suspensions
49
Solutions
- Tiny solute particles
| - Do not settle out or scatter
50
Example of solution
Mineral water
51
Colloids
- Larger solute particles than solution
- Scatter light
- Do not settle out
52
Example of colloid
Jelly
53
Suspension
- Very large solute particles
- Settle out
- May scatter light
54
Example of suspension
Blood
55
Mixtures vs compounds
There is NO chemical bonding between components of a mixture
atomic properties do not change in a mixture
Mixtures can be separated physically by straining, evaporating, filtering
Compounds need chemical binds to be broken to separate
Mixtures can be heterogeneous or homogenous. Compounds are always homogenous.
56
What are chemical bonds
Energy relationships between electrons of the reacting atoms
57
What happens to chemical bonds
Made or broken quickly ( otherwise slow metabolism )
58
What are the types of covalent bonds
- Ionic
- Covalent
- Hydrogen
59
Where do electrons orbit
Electron shells ( from nucleus )
60
What does each shell represent
Different energy level
| Each shell can only hold certain number of e-'s
61
What type of energy do electrons have
Potential energy
62
Which electrons have most potential energy and why
Electrons furthest from +ve nucleus
| Need more energy to position so far away from +ve field
63
What electrons take part in chemical bonding
Electrons in outermost energy level
64
What is outer shell called
Valence shell
| Each element has different valence shell depending on number of electrons
65
What does chemical inert mean
```
When the outermost energy level is full
Unreactive
Stable
Not react easily with other elements due to full outer shell
Noble gases
```
66
What happens to atoms with less than 8 electrons in their 2nd shell
Tend to gain, lose or share electrons with other atoms to achieve stability = form chemical bonds
67
What happens to atoms with more than 8 electrons in their 2nd shell
Atoms interact and stabilize with 8 electrons in valence shell
Rule of 8
68
What do atoms without 8 electrons in their valence shell do
Interact to leave 8 in their valence shell and are then stable.
69
What are Ionic bonds
Electrons donated from one atom to another to make full outer shell = stable
70
What happens to electrons in ionic bonds
Lost or gained
71
What is electron donor
Cation
| Positive
72
What is electron acceptor
Anion
| Negative
73
What is formed from transfer of electrons
Ions
| Lost or gained electrons
74
How does ionic bond form
Two oppositely charged ions attract
| chemical bond
75
What is covalent bond
Electrons can be ‘shared’ between two atoms
76
How does atoms stabilise
If both atoms now have 8 electrons in valence shell
77
What are the types of covalent bonds
Single bonds - 2 e-'s shared ( 1 bond )
Double bonds - 4 e-'s shared ( 2 bonds )
Triple bonds - 6 e-'s shared ( 3 bonds )
78
How is covalent bond formed
Electrons orbit both valence shells - e- clouds overlap - orbit both nuclei at same time = share
79
What are non - polar molecules
If the electrons are shared equally between both atoms
| No charge difference = charge balanced
80
What doesnt allow equal share of electrons sometimes
3D shape of molecules or electron sharing ability = polar molecules - dipoles
81
Example of non - polar molecule
CO2 - liner and symmetrical
82
What are the electron sharing abilities of atoms
electronegativity
(6-7 valence shell electrons)
electro positivity
(1-2 valence shell electrons)
83
What are polar molecules
Unequal sharing of electrons, slight negative charge at one end, slight positive charge at other end of molecule
84
Example of polar molecule
Water
85
What is weakest bond
Hydrogen bond
86
When does hydrogen bond form
-H is already covalently bonded to an electronegative atom (N or O)
-Another electron hungry atom
attracts the H
-The gap is ‘bridged’
87
Where is hydrogen bonding common
Between dipoles
| e.g. H20
88
What is hydrogen bond
Attraction between a H atom carrying partial +ve charge and an electronegative atom
2 molecules attracted to each other - not sharing e-'s
89
What is strongest bond and why
Covalent
| Electrons interact with each other = sharing electrons = neither of them want to give up electrons = tightly bound
90
When do chemical reactions occur
When electrons are gained or lost
91
Why is matter in constant motion
Due to kinetic energy
92
What happens in solid
vibrations ( slight movement between atoms )
93
What happens in liquids and gases
Dart around and can collide. This interaction can initiate a chemical reaction.
94
What happens during chemical reaction
Chemical bonds are altered...
- formed ( break existing bonds )
- rearranged ( same molecule )
- broken ( need energy )
95
What are the types of chemical reactions
- Synthesis: react molecules together
- Decomposition: bonds broken from larger to smaller molecules
- Exchange/displacement: Bonds both made and broken
96
What type of reactions are oxidation - reduction reactions
Decomposition reaction and an exchange reaction
Ionic reaction or covalent bonding
Basis for all food fuel breakdown reactions
97
Oxidation
One reactant loses electrons - electron donor
98
Reduction
One reactant gains electrons - electron acceptor
99
How is a substance oxidised
Losing a H or gaining an O
| Electrons that ‘belonged’ to the substance are lost
100
Example of oxidation - reduction reaction
Respiration
| C6H2O6 + 6O2 -> 6CO2 + 6H2O + ATP
101
What are chemical bonds
Stored potential energy
102
What are types of chemical reactions
- Exergonic
- Endergonic
In cells exergonic and endergonic tend to go hand in hand.
ie we do not want to lose energy from the system as heat, so we harness it.
103
Exergonic
Release energy - catabolic or oxidative - break molecule
104
Endergonic
Absorb energy - anabolic or reduction - need energy to form chemical bonds
105
What are factors that influence chemical reaction rates
Temperature
Concentration
Particle size
Catalysts (enzymes
106
How does temp affect rate of chemical reaction
higher temp = more energy = more chance of energy occuring
107
How does concentration affect reaction rate
increase conc of molecules - increase collisons - more energy transferred from one molecule to another = increase chance of reaction occuring
108
How does particle size affect reaction rate
increase particle size = more likely to collide = larger atom = more potential energy = increase chance of reaction occurring
109
How does catalysts affect reaction rate
catalysts increase reaction rate
| Bring 2 molecules together, create right conditions
110
Organic compounds
Contain carbon
| Covalently bonded
111
Inorganic compounds
Doesnt contain carbon
112
Example of inorganic compounds
Water, salts, acids, bases
113
Which bonding in organic compounds
Covalent bonds
114
Water
- high heat capacity - store lots of heat between molecules
- high heat of vaproisation - turn into liquid
- ‘Universal’ solvent – due to being a dipole - polar solvent
- essential reactant in many reactions - condensation and hydrolysis
- water is compressible - cushioning for body cells
115
How much water in cells
60 - 80%
116
What are salts
Ionic compounds
| Does not include those that have H+ or OH-
117
What happens when salts are dissolved in water
They dissociate into component ions = bonds broken
118
What are ions in solution
Electrolytes
119
Uses of salts
- Electrolyte properties of Na and K are essential in nerve impulse transmission
and muscle contraction
-Bones are calcified with calcium salts (calcium phophates)
120
Acids and bases
- These are also electrolytes
| - Dissociate into ions in water and conduct electricity
121
What are acids
- Releases H+ (hydrogen ions) = Proton donors
- When dissolved in water the release hydrogen ions (protons), and anions.
- HCL H+ + Cl-
122
What are bases
- Bind H+ (hydrogen ions) = Proton acceptor
- Hydroxides
- These also dissociate in water = hydroxyl ions and cations
- NaOH Na+ + OH-
- The hydroxyl is then free to bind to free protons
- H+ + OH- H2O
- This means bases can reduce the acidity of a solution by reducing hydrogen ions.
123
What is acidity
Free H+ ions in solution
124
Buffers
-Living cells are sensitive to changes in pH
-Homeostasis of acid-base balance is maintained by the kidneys (urinary system) and lungs (respiratory system)
- And by chemicals – proteins or other molecules that act as buffers
- These bind or release
H ions quickly.
- Consist of weak acid
and weak base
125
`Example of buffer
Bicarbonate
126
What does universe consists of
Matter
127
What is the difference between all three states
Amount of energy put into system - heat
128
What has smallest unit of molecule of that compound
Compounds
Different properties of whole compound compared to the individual atoms they contain
e.g. NaCl = compound = salt = :)
BUT Na = individual atom = shiny white metal = cant eat = :(
Cl = individual atom - posionous green gas = :(
129
Which type of chemical reactions is anabolic
Synthesis
130
Which type of chemical reactions is catabolic
Decomposition
