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Biology 12U > 1.1 Fundamental Chemistry of Life > Flashcards

1.1 Fundamental Chemistry of Life Flashcards

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1
Q

Element definition

A

An element is a pure substance that cannot be broken down into simpler substances using ordinary chemical or physical techniques.

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2
Q

The smallest particle of an element is an ____.

A

atom

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3
Q

Chemical compound definition

A

A chemical compound is a stable combination of
different elements that are held together by chemical bonds.

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4
Q

Which four elements make up
96% of the weight of a living organism?

A

Carbon, hydrogen, oxygen and nitrogen

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5
Q

Definition of trace elements

A

Elements that are required by organisms and are found in such small amounts

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6
Q

A deficiency in any trace element can lead to _________ _________.

A

health problems

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7
Q

Why does an atom have no net charge?

A

An atom has no net charge because the number of protons is equal to the number of electrons.

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8
Q

Isotope definition

A

Isotopes are different forms of the
same element, with different atomic masses.

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9
Q

Because isotopes of the same element
have the same number of protons and electrons, they behave _______ ______ _____ in a
chemical reaction.

A

exactly the same

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10
Q

Radioisotope definition

A

A radioactive isotope of an element

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11
Q

Radioactive decay continues at a ______ rate, with a constant proportion of radioisotope atoms breaking down during a given time interval.

A

steady

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12
Q

The rate of decay of a radioisotope is _________ of chemical reactions or environmental conditions,
such as ________ or _______.

A

independent; temperature; pressure

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13
Q

Radioisotopes generally behave the _______ way in cells as non-radioactive isotopes of the same element.

A

same

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14
Q

True or false:

Radioisotopes are used to study many biochemical reactions and to perform basic
techniques, such as DNA sequencing.

A

true

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15
Q

How does the arrangement of electrons determine the chemical properties of an atom?

A

Only electrons are usually directly involved in a chemical reaction.

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16
Q

Orbital definition

A

A region of space that is occupied by electrons located around the nucleus of an atom

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17
Q

True or false:

Even though one or two electrons may occupy a given orbital, the least stable and balanced condition occurs when the orbital contains two electrons.

A

False

The MOST stable and balanced condition occurs when the orbital contains 2 electrons

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18
Q

Electron orbitals are grouped into energy levels, which are sometimes called ________ ______.

A

energy shells

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19
Q

The lowest energy shell of an atom is
______ to the nucleus.

A

closest

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20
Q

True or false:

The second and third energy shells hold up to eight and 18 electrons, respectively.

A

True

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21
Q

The farther away the electron is from the nucleus, the ________ its energy.

A

greater

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22
Q

Valence electrons definition

A

Valence electrons are the electrons in an atom’s outermost energy shell, or valence shell.

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23
Q

Atoms with an outermost energy shell that is not completely filled with electrons tend to be chemically __________ atoms.

A

reactive

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24
Q

Atoms with a completely filled outermost
energy level are chemically ________.

A

inactive (inert)

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25
Q

Atoms can also become more _______ when they share electrons in such away that their
_________ orbitals are filled.

A

stable; valence

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26
Q

The _______ of electrons in the valence shells of atoms creates what are called _________ electron orbitals.

A

sharing; hybridized

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27
Q

In a hybridized electron orbital, there is a
direct ________ of the valence electron orbitals of the two atoms, so the orbital is a __________ of two different orbitals.

A

overlap; combination

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28
Q

Sharing electrons is the most common way for atoms to _______ and form __________ molecules.

A

bond; biological

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29
Q

Atoms of reactive elements combine with each other to form compounds, these atoms form a _______ attraction to one another called a _________ ________.

A

stable; chemical bond

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30
Q

Ionic bond definition

A

a bond that results from the attraction between two oppositely charged atoms or molecules

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31
Q

Cation vs. Anion

A

Cation - an ion that has a positive charge

Anion - an ion that has a negative charge

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32
Q

Ions are very strongly attracted to ______ molecules. As a result, ionic compounds tend to __________ and dissolve in water, forming ___________ ions.

A

water; dissociate; hydrated

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33
Q

True or false:

Covalent bonds form when atoms share two or more pairs of valence electrons.

A

False

Covalent bonds form when atoms share ONE or more pairs of valence electrons

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34
Q

The strength of a covalent bond
depends on the _____________ of the atoms involved in the sharing of the electron pair.

A

electronegativity

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35
Q

Electronegativity definition

A

Electronegativity is the measure of an atom’s attraction for additional electrons.

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36
Q

The number of covalent bonds that an atom can form is usually equal to the number of additional _________ needed to fill its __________ shell.

A

electrons; valence

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37
Q

True or false:

The number and tetrahedral arrangement of the bonds around a carbon atom allow carbon atoms to link together in more complicated biological compounds.

A

True

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38
Q

You can predict the arrangement of the bond angles around an atom using the ___________________________ theory

A

valence shell electron pair repulsion (VSEPR)

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39
Q

The VSEPR theory states that because electrons
are _______ charged, valence electron pairs ______ one another and move as far apart
from one another as possible.

A

negatively; repel

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40
Q

The more electronegative an atom is, the more
___________ it attracts electrons.

A

strongly

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41
Q

Electronegativity _________ as the distance between the electrons and the nucleus ___________.

A

increases; decreases

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42
Q

The unequal sharing of electrons between two atoms with different electronegativity
results in a _______ ________ bond.

A

polar covalent

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43
Q

The atom that attracts the valence electrons more strongly carries a partial ________ charge, which results in the other atom carrying a partial ______ charge.

A

negative; positive

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44
Q

True or false:

The more electronegative oxygen pulls the electrons closer, so the oxygen atom has a partial positive charge.

A

False

The oxygen atom has a partial NEGATIVE charge

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45
Q

Polar molecules _________ and align themselves to other polar molecules and tend to be _______ in water.

A

attract; soluble

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46
Q

Intermolecular force definition

A

The force of attraction between two molecules

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47
Q

Van der Waals forces definition

A

Very weak attractions between two molecules, or
parts of molecules, when they are close together

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48
Q

Hydrogen bond definition

A

The attractive force between a partially positively charged hydrogen atom and a partially negatively charged atom in another molecule

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49
Q

True or false:

Hydrogen bonds are the strongest and most biologically significant form of van der Waals forces.

A

True

50
Q

Although most of the strongest bonds in living organisms are covalent, weaker hydrogen bonds
are crucial to the function of _____ and __________ __________

A

cells; cellular processes.

51
Q

The weaker attractive force of hydrogen bonds makes them much easier to _____ than covalent or ionic bonds, especially when there is an increase in __________, which increases the __________ of the molecules.

A

break; temperature; movement

52
Q

Long linear ______ molecules have numerous OH functional groups and are able to form very _______ solid fibres.

A

cellulose; strong

53
Q

Globular shaped molecules such as ________ have fewer accessible atoms for van der Waals forces and therefore tend to form less ______ solids.

A

starches; rigid

54
Q

All chemical reactions involve the _______ and formation of chemical bonds, thereby changing the ________ of atoms and ions.

A

breaking; arrangements

55
Q

What are the four major types of chemical reactions that are common in biological processes?

A

Dehydration, hydrolysis, neutralization, and redox reactions.

56
Q

Dehydration reaction

A

Also called condensation reactions, consist of the removal of an -OH and an -H from two reactant molecules

The -OH and -H form a water molecule, while the two reactant molecules are joined together

57
Q

Dehydration reactions are the most common method used by cells to _____ smaller molecules and assemble extremely large _____________, such as complex carbohydrates and proteins.

A

join; macromolecules

58
Q

Hydrolysis reaction definiton

A

A chemical reaction in which water is used as a reactant to split a larger molecule into smaller
subunits

59
Q

Neutralization reaction definition

A

A reaction in which an acid and a base combine to create a salt and water

60
Q

Redox reaction definition

A

During a redox reaction (named for “reduction” and “oxidation”), electrons are lost from one atom and gained by another atom.

61
Q

Oxidation refers to the ______ of electrons. The result is an ________ molecule or atom.

A

loss; oxidized

62
Q

The oxidation of one molecule is always linked to the _________ of another molecule.

A

reduction

63
Q

The term reduction refers to the _____ of electrons. In a redox reaction, the oxidizing
agent is the molecule or atom being ________.

A

gain; reduced

64
Q

What is the reducing agent in a redox reaction?

A

The reducing agent is the molecule
or atom being oxidized.

65
Q

The term “oxidation” also refers to the transfer of entire _______ atoms (and their electrons) from ______ electronegative atoms to _____
electronegative atoms.

A

hydrogen; less; more

66
Q

True or false:

During oxidation reactions in biological systems, the electrons involved are more strongly attracted to the oxidizing agent.

A

True

67
Q

Redox reactions involve electrons moving from where they are ______ held to where they are
more ______ held.

A

weakly; strongly

68
Q

Redox reactions are responsible
for most of the _______ _______ within cells.

A

energy transfer

69
Q

Differences in electronegativity result in _______ ________.

A

bond polarity

70
Q

Hydrolysis occurs when a bond in a large molecule is _______, and ______ is added to the resulting subunits.

A

broken; water

71
Q

How do bonding arrangements in a molecule affect the shape of the molecule?

A

To minimize their energy, electron pairs in atoms move as far away from each other as possible, which causes the bonds to be at different angles from one another.

72
Q

Compare ionic bonds with covalent bonds.

A

Ionic bonds form when an electron is transferred from one atom to another, and the resulting ions are attracted to each other.

Covalent bonds form when atoms share electrons to fill their valence shell.

73
Q

How can the atomic composition of a molecule affect its polarity?

A

For a molecule to be polar it must contain atoms that differ in electronegativity and the resulting electronegative bonds must be arranged asymmetrically in the molecule.

74
Q

How can the shape of a molecule affect its polarity?

A

The asymmetrical shape of a molecule containing polar bonds can result in an overall unbalanced
distribution of charge, making the molecule as a whole polar.

75
Q

What effect do the polarity, size, and shape of a
molecule have on the physical properties of the
molecule?

A

Polarity, size, and shape can affect the solubility, melting and boiling points, and brittleness
of molecules.

76
Q

How does polarity, size, and shape of a
molecule influence intermolecular forces?

A

Larger molecules have greater number of intermolecular forces, so the molecule is held more tightly to another molecule.

Linear molecules also have greater intermolecular forces than globular molecules because of their ability to get closer together.

Polar molecules have stronger forces of attraction between them.

77
Q

How do polar covalent bonds and non-polar
covalent bonds differ?

A

Electrons are not shared equally in a polar covalent bond while electrons are shared relatively equally in non-polar covalent bonds

78
Q

In a bond between nitrogen and hydrogen (N-H),
which atom will the electrons be closer to?

A

Nitrogen has a higher electronegativity than hydrogen, so the electrons will be closer to the
nitrogen atom

79
Q

Oxygen plays a major role in biological molecules. Explain how oxygen plays a role in polarity, bond shape, and redox reactions.

A

Oxygen has a very high electronegativity, so it strongly attracts electrons of other elements and forms polar bonds.

Oxygen has two pairs of non-bonding electrons in its out orbital and therefore forms two bonds that are not aligned—oxygen produces
“bent” molecules.

Oxygen also plays a role in redox reactions. It is frequently the oxidizing reagent because of its strong electronegativity in a reaction.

80
Q

In what ways do hydrogen bonds produce
attractive forces between molecules?

A

Hydrogen bonds produce attractive forces by lining up partially positively charged hydrogen atoms with a partially negative charged atoms of different molecules.

81
Q

How do hydrogen bonds influence the physical
properties of water?

A

Hydrogen bonds give water a high heat capacity, high melting and boiling points, and high
surface tension, cohesion and adhesion.

82
Q

Describe dehydration and hydrolysis. How are these two types of reactions related?

A

Dehydration is the removal of –OH and –H from two reactant molecules, which allows the
reactant molecules to form a bond, as well as creating water.

Hydrolysis is the breaking of a bond between two subunits and the addition of water in the form of –OH and –H to the subunits.

Dehydration is the reverse of hydrolysis, and vice versa.

83
Q

Can a reduction reaction occur independently
of an oxidation reaction, or vice versa? Why or
why not?

A

The reduction or oxidation of one molecule always implies the oxidation or reduction of
another molecule; they cannot occur independently.

84
Q

All organic compounds inside of living organisms are made of _ _ _ _

A

C, H, O, N

85
Q

Matter is made up of small units called ______ which combine to form more complex structures called __________

A

atoms; molecules

86
Q

elements are _____________ that can’t be broken down into simpler substances

A

pure substances

87
Q

all organic compounds contain _______ atoms and may also contain ________ and ________

A

carbon, hydrogen, oxygen

88
Q

which elements are included in the 96% composition of living things?

A

carbon, oxygen, hydrogen and nitrogen

89
Q

which elements are included in the 4% composition of living things?

A

calcium, phosphorus, potassium, sulphur, sodium, chlorine, magnesium

90
Q

which elements are trace elements?

A

iodine and iron

91
Q

what does the number of protons determine?

A

the type of element

92
Q

why are atoms neutral?

A

they have the same number of protons as electrons

93
Q

atomic mass

A

the weight of protons and neutrons (electrons are so small we ignore their mass)

94
Q

isotope

A

a form of an element that has the same number of protons but different number of neutrons

(behave exactly the same in chemical reactions)

95
Q

radioisotopes

A

unstable isotope that decays giving off radiation

-transforms into an atom of another element

96
Q

example of a radioisotope

A

14C is unstable and one neutron splits into an electron
and a proton.

When this happens 14C decays into 14N

97
Q

radioactive decay

A

occurs at a steady and
measurable rate

can be used to determine the
age of rocks and fossils.

98
Q

radioactive tracers

A

radioisotopes can be used
to trace the path of atoms throughout the body.

99
Q

ionic bonds

A

bond that forms between two oppositely charged atoms/molecules

-positive cation and negative anion

100
Q

covalent bonds

A

when atoms share valence electrons

101
Q

electronegativity

A

the measure of an atom’s attraction to shared electrons

102
Q

high electronegativity= _____ attraction of electrons

A

strong

103
Q

low electronegativity= _____ attraction of electrons

A

weak

104
Q

why is oxygen slightly more negative in an H2O molecule?

A

oxygen has a stronger pull on electrons and becomes slightly more negative

105
Q

why is hydrogen slightly more positive in an H2O molecule?

A

hydrogen has a weaker pull on electrons and becomes slightly more positive

106
Q

polar covalent bond

A

an unequal sharing of electrons

107
Q

_____ molecules are generally water soluble

A

polar

108
Q

_____ molecules are generally NOT water soluble

A

non-polar

109
Q

intermolecular forces

A

forces of attraction between molecules

110
Q

hydrogen bonds

A

attractive force between slightly positive hydrogen atoms and a slightly negative atom in another molecule

-e.g. water

111
Q

dipole dipole force

A

attractive force between slightly positive atoms (not hydrogen) and a slightly negative atom in another molecule

112
Q

van der Waal forces

A

very
weak attractions between two
molecules, or parts of molecules
when they are close together

Larger molecules have larger
forces of attraction than smaller
molecules

113
Q

how do van der Waal forces form

A

Form from the momentary
attractions of electrons to nuclei
of other molecules

114
Q

dehydration rxn is also known as …

A

condensation rxn

115
Q

dehydration rxn

A

Involves the joining of two molecules through the
removal of water

116
Q

In which reaction does one molecule lose a Hydrogen atom while the other loses an –OH group?

A

dehydration/condensation rxn

117
Q

hydrolysis rxn

A

involves splitting a larger
molecule apart by adding a water molecule

118
Q

Which reaction involves adding an –OH group to one molecule and a
Hydrogen atom to the other?

A

hydrolysis rxn

119
Q

neutralization rxn

A

a reaction in which
an acid and a base combine to create a salt and
water

120
Q

redox rxn

A

electron transfer rxn

121
Q

reduction

A

gaining of electrons

122
Q

oxidation

A

loss of electrons

Biology 12U (45 decks)

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