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Biological Sciences > Lecture 4 - The chemistry of life > Flashcards

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

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2
Q

What 3 states does matter exist in

A

Solid
Liquid
Gas

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3
Q

Solid

A

Definite shape and volume

Bones,teeth ( not much water, a lot of salts )

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4
Q

Liquid

A

Definite volume, flows to fill space

Blood plasma

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5
Q

Gas

A

No defined shape nor volume

Air we breath in and out

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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
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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

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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

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9
Q

What are the 4 forms of energy

A
  • Chemical energy
  • Electrical energy
  • Mechanical energy
  • Radiant energy
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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.

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11
Q

What is electrical energy

A

Movement of charged particles through, or along cell membranes.
Nervous system - action potential

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12
Q

What is mechanical energy

A

Energy directly involved in moving matter.

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13
Q

What is radiant energy

A

Energy that travels in waves.

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14
Q

Law of energy

A

Energy can neither be created nor destroyed

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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
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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.

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17
Q

Elements

A
  • All matter is composed of elements
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18
Q

Can elements be broken down into smaller substances

A

No

it is the smallest building block

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19
Q

How many elements are there

A

118……
92 in nature
26 - in particle accelerator - smash elements together and see what they create

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20
Q

What 4 elements make up most of our body weight

A

C , O , H , N

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21
Q

What is each element composed of

A

An atom

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22
Q

Size range of atoms

A

Smallest < 0.1nm

Largest ~0.5nm

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23
Q

Physical properties of elements

A

Detected with sense ie colour, taste

Measurable ie boiling point

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24
Q

Chemical properties of elements

A

How elements interact with

each other

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25
Q

Charge and mass of proton

A

positive

1

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26
Q

Charge and mass of neutron

A

neutral

1

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27
Q

Charge and mass of electron

A

Negative

1/1,840

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28
Q

What do electrons do and what does it allow

A

Orbit the nucleus
Spin on outside = allows it to interact with other things in environment
- Charge difference holds it together

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29
Q

What makes up nucleus

A

Protons and neutrons

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30
Q

Charge of nucleus

A

Positive

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31
Q

What are atoms charge

A

Electrically neutral = same number of protons and electrons

i.e. 1 e- added = 1 proton also added

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32
Q

How do elements differ from each other

A

By number of protons, neutrons and electrons

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33
Q

What do the number of protons, neutrons and e-‘s give rise to

A

Variation in chemical and physical properties of the elements.

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34
Q

What are isotopes

A

Structural variants of elements

Electrons and protons remain constant in number. Different number of neutrons

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35
Q

What are radioisotopes

A

Isotopes formed from radioactivity e.g. C14

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36
Q

What is radioactivity

A

Atomic decay - releases forms of energy - mini explosion - destroys cells - radiation bad -energy source

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37
Q

Process of radioactivity

A
  • 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
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38
Q

What is the mini explosion and what is released

A

Atomic decay

  • alpha particles (2p + 2n) - helium
  • beta particles (electron-like particles)
  • gamma rays (electromagnetic energy)
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39
Q

What happens to energy released during radioactive decay

A

Transformed into different element

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40
Q

What is molecule of element

A

When atoms of same element combine

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41
Q

What is molecule of compound

A

Different kinds of atom combine

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42
Q

How does neutrons affect atomic decay

A

More neutrons = more atomic weight

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43
Q

Do atoms exist in free state

A

Not usually

They are often chemically combined with other atoms

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44
Q

Why form compounds or elements

A

To become stable

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45
Q

Why are atoms not in a free state

A

Unstable

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46
Q

What are mixtures

A

2+ components physically intermixed

- Same matter, don’t particularly interact

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47
Q

Where is most matter found

A

In mixtures

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48
Q

What are the 3 types of mixtures

A
  • Solutions
  • Colloids
  • Suspensions
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49
Q

Solutions

A
  • Tiny solute particles

- Do not settle out or scatter

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50
Q

Example of solution

A

Mineral water

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51
Q

Colloids

A
  • Larger solute particles than solution
  • Scatter light
  • Do not settle out
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52
Q

Example of colloid

A

Jelly

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53
Q

Suspension

A
  • Very large solute particles
  • Settle out
  • May scatter light
54
Q

Example of suspension

A

Blood

55
Q

Mixtures vs compounds

A

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
Q

What are chemical bonds

A

Energy relationships between electrons of the reacting atoms

57
Q

What happens to chemical bonds

A

Made or broken quickly ( otherwise slow metabolism )

58
Q

What are the types of covalent bonds

A
  • Ionic
  • Covalent
  • Hydrogen
59
Q

Where do electrons orbit

A

Electron shells ( from nucleus )

60
Q

What does each shell represent

A

Different energy level

Each shell can only hold certain number of e-‘s

61
Q

What type of energy do electrons have

A

Potential energy

62
Q

Which electrons have most potential energy and why

A

Electrons furthest from +ve nucleus

Need more energy to position so far away from +ve field

63
Q

What electrons take part in chemical bonding

A

Electrons in outermost energy level

64
Q

What is outer shell called

A

Valence shell

Each element has different valence shell depending on number of electrons

65
Q

What does chemical inert mean

A 
When the outermost energy level is full
Unreactive
Stable
Not react easily with other elements due to full outer shell
Noble gases
66
Q

What happens to atoms with less than 8 electrons in their 2nd shell

A

Tend to gain, lose or share electrons with other atoms to achieve stability = form chemical bonds

67
Q

What happens to atoms with more than 8 electrons in their 2nd shell

A

Atoms interact and stabilize with 8 electrons in valence shell
Rule of 8

68
Q

What do atoms without 8 electrons in their valence shell do

A

Interact to leave 8 in their valence shell and are then stable.

69
Q

What are Ionic bonds

A

Electrons donated from one atom to another to make full outer shell = stable

70
Q

What happens to electrons in ionic bonds

A

Lost or gained

71
Q

What is electron donor

A

Cation

Positive

72
Q

What is electron acceptor

A

Anion

Negative

73
Q

What is formed from transfer of electrons

A

Ions

Lost or gained electrons

74
Q

How does ionic bond form

A

Two oppositely charged ions attract

chemical bond

75
Q

What is covalent bond

A

Electrons can be ‘shared’ between two atoms

76
Q

How does atoms stabilise

A

If both atoms now have 8 electrons in valence shell

77
Q

What are the types of covalent bonds

A

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
Q

How is covalent bond formed

A

Electrons orbit both valence shells - e- clouds overlap - orbit both nuclei at same time = share

79
Q

What are non - polar molecules

A

If the electrons are shared equally between both atoms

No charge difference = charge balanced

80
Q

What doesnt allow equal share of electrons sometimes

A

3D shape of molecules or electron sharing ability = polar molecules - dipoles

81
Q

Example of non - polar molecule

A

CO2 - liner and symmetrical

82
Q

What are the electron sharing abilities of atoms

A

 electronegativity
(6-7 valence shell electrons)
 electro positivity
(1-2 valence shell electrons)

83
Q

What are polar molecules

A

Unequal sharing of electrons, slight negative charge at one end, slight positive charge at other end of molecule

84
Q

Example of polar molecule

A

Water

85
Q

What is weakest bond

A

Hydrogen bond

86
Q

When does hydrogen bond form

A

-H is already covalently bonded to an electronegative atom (N or O)
-Another electron hungry atom
attracts the H
-The gap is ‘bridged’

87
Q

Where is hydrogen bonding common

A

Between dipoles

e.g. H20

88
Q

What is hydrogen bond

A

Attraction between a H atom carrying partial +ve charge and an electronegative atom
2 molecules attracted to each other - not sharing e-‘s

89
Q

What is strongest bond and why

A

Covalent

Electrons interact with each other = sharing electrons = neither of them want to give up electrons = tightly bound

90
Q

When do chemical reactions occur

A

When electrons are gained or lost

91
Q

Why is matter in constant motion

A

Due to kinetic energy

92
Q

What happens in solid

A

vibrations ( slight movement between atoms )

93
Q

What happens in liquids and gases

A

Dart around and can collide. This interaction can initiate a chemical reaction.

94
Q

What happens during chemical reaction

A

Chemical bonds are altered…

  • formed ( break existing bonds )
  • rearranged ( same molecule )
  • broken ( need energy )
95
Q

What are the types of chemical reactions

A
  • Synthesis: react molecules together
  • Decomposition: bonds broken from larger to smaller molecules
  • Exchange/displacement: Bonds both made and broken
96
Q

What type of reactions are oxidation - reduction reactions

A

Decomposition reaction and an exchange reaction
Ionic reaction or covalent bonding
Basis for all food fuel breakdown reactions

97
Q

Oxidation

A

One reactant loses electrons - electron donor

98
Q

Reduction

A

One reactant gains electrons - electron acceptor

99
Q

How is a substance oxidised

A

Losing a H or gaining an O

Electrons that ‘belonged’ to the substance are lost

100
Q

Example of oxidation - reduction reaction

A

Respiration

C6H2O6 + 6O2 -> 6CO2 + 6H2O + ATP

101
Q

What are chemical bonds

A

Stored potential energy

102
Q

What are types of chemical reactions

A
  • 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
Q

Exergonic

A

Release energy - catabolic or oxidative - break molecule

104
Q

Endergonic

A

Absorb energy - anabolic or reduction - need energy to form chemical bonds

105
Q

What are factors that influence chemical reaction rates

A

Temperature
Concentration
Particle size
Catalysts (enzymes

106
Q

How does temp affect rate of chemical reaction

A

higher temp = more energy = more chance of energy occuring

107
Q

How does concentration affect reaction rate

A

increase conc of molecules - increase collisons - more energy transferred from one molecule to another = increase chance of reaction occuring

108
Q

How does particle size affect reaction rate

A

increase particle size = more likely to collide = larger atom = more potential energy = increase chance of reaction occurring

109
Q

How does catalysts affect reaction rate

A

catalysts increase reaction rate

Bring 2 molecules together, create right conditions

110
Q

Organic compounds

A

Contain carbon

Covalently bonded

111
Q

Inorganic compounds

A

Doesnt contain carbon

112
Q

Example of inorganic compounds

A

Water, salts, acids, bases

113
Q

Which bonding in organic compounds

A

Covalent bonds

114
Q

Water

A
  • 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
Q

How much water in cells

A

60 - 80%

116
Q

What are salts

A

Ionic compounds

Does not include those that have H+ or OH-

117
Q

What happens when salts are dissolved in water

A

They dissociate into component ions = bonds broken

118
Q

What are ions in solution

A

Electrolytes

119
Q

Uses of salts

A
  • Electrolyte properties of Na and K are essential in nerve impulse transmission
    and muscle contraction
    -Bones are calcified with calcium salts (calcium phophates)
120
Q

Acids and bases

A
  • These are also electrolytes

- Dissociate into ions in water and conduct electricity

121
Q

What are acids

A
  • Releases H+ (hydrogen ions) = Proton donors
  • When dissolved in water the release hydrogen ions (protons), and anions.
  • HCL  H+ + Cl-
122
Q

What are bases

A
  • 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
Q

What is acidity

A

Free H+ ions in solution

124
Q

Buffers

A

-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
Q

`Example of buffer

A

Bicarbonate

126
Q

What does universe consists of

A

Matter

127
Q

What is the difference between all three states

A

Amount of energy put into system - heat

128
Q

What has smallest unit of molecule of that compound

A

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
Q

Which type of chemical reactions is anabolic

A

Synthesis

130
Q

Which type of chemical reactions is catabolic

A

Decomposition

Biological Sciences (27 decks)

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