Chapter 2 life chemistry and water Flashcards

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1
Q

element

A

a pure substance that cannot be broken into simpler substances by ordinary chemical or physical techniques

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2
Q

trace elements (2)

A
  1. an element that occurs in organisms in very small quantities (less than 0.01%) ;
  2. in nutrition, a mineral required by organisms only in small amounts
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3
Q

Avogadro’s number

A

the number 6.022 X 10~23 derived by dividing the atomic weight of any element by the weight of an atom of that element

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4
Q

molecule

A

a unit composed of atoms combined chemically in fixed numbers and ratios

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5
Q

formula

A

the name of a molecule written in chemical shorthand

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6
Q

compounds

A

a molecule whose component atoms are different

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7
Q

isotopes

A

a distinct form of atoms of an element, all with the same number of protons but a different number of neutrons and therefore a different mass/ nucleon number

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8
Q

Daltons (Da)

A

a standard unit of mass, about 1.66 x 10~-24 grams

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9
Q

molarity (M)

A

the number of moles of a substance dissolved in 1 litre of solution

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10
Q

pH scale

A

the numerical scale from 0 to 14 used by scientists to measure acidity

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11
Q

weight

A

a measure of the pull of gravity on an object

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12
Q

radioactivity

A

the giving off of particles of matter and energy by decaying nuclei

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13
Q

radioisotope

A

an unstable, radioactive isotope

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14
Q

radiometric dating

A

a dating technique that uses the clockwork decay of unstable isotopes to estimate the age of organic material, rocks, or fossils that contain them

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15
Q

orbital (2)

A
  1. the region of space where the electron occupies most of the time.
  2. a region of space around the nucleus of an atom that can be occupied by one or two electrons
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16
Q

shells/ energy levels

A

regions of space within an atom where electrons are found

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17
Q

valence electron

A

an electron in the outmost energy level of an atom

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18
Q

base

A

proton acceptor that reduces the H+ concentration of a solution

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19
Q

ionic bond

A

a bond that results from electrical attractions between atoms that gain or lose valence electrons completely

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20
Q

ion

A

a positively or negatively charged atom

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21
Q

anion

A

a negatively charged ion

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22
Q

ice lattice

A

a rigid, crystalline formed when a water molecule in ice forms 4 hydrogen bonds with neighboring molecules

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23
Q

non-polar covalent bond

A

bond in which electrons are shared equally or nearly equally; the atoms have NO charge

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24
Q

reactants

A

the atoms or molecules entering a chemical reaction

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25
Q

non-polar association

A

association that occurs when non-polar molecules clump together

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26
Q

hydrophilic

A

polar molecules that associate readily with water

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27
Q

hydrophobic

A

non-polar molecules/substances that are excluded by water and other polar molecules

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28
Q

hydrogen bond

A

non-covalent bond formed by unequal electron sharing between hydrogen atoms and oxygen , nitrogen, or sulfur

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29
Q

solute

A

the molecules of a substance dissolved in water.

30
Q

concentration

A

the number of molecules or ions of a substance in a unit volume of space

31
Q

molecular weight

A

the weight of a molecule in grams, equal to the total mass number of its atoms

32
Q

heat of vaporization

A

the heat required to give water molecules enough energy of motion to break loose from liquid water and form a gas

33
Q

water lattice

A

an arrangement formed when a water molecule in liquid establishes an average of 3.4 hydrogen bonds with its neighbors

34
Q

kilocalorie (kcal)

A

the amount of heat required to raise 1 kg of water by 1 degree Celsius, the scientific unit equivalent to a Calorie and equal to a 1000 small calories

35
Q

matter

A

anything that occupies space and has mass

36
Q

atom

A

the smallest unit that retains the chemical and physical properties of an element

37
Q

atomic nucleus

A

the nucleus of a atom, which consists of sub-atomic particles called protons and neutrons

38
Q

proton

A

a subatomic particle situated in the nucleus of an atom that carries one unit of charge

39
Q

neutron

A

uncharged subatomic particle in the nucleus of an atom

40
Q

electron

A

negatively charged particle situated outside the nucleus of an atom

41
Q

atomic number

A

the number of protons in the nucleus of each kind of atom

42
Q

mass number

A

the total number of protons and neutrons in the atomic nucleus

43
Q

mass

A
  1. the amount of matter in an object.

2. my definition: the degree to which a body is reluctant to a change in motion

44
Q

tracer

A

isotope used to label molecules so that they can be tracked as they pass through biochemical reactions

45
Q

chemical bond

A

link formed when atoms of reactive elements combine into molecules

46
Q

cation

A

a positively charged ion

47
Q

polar covalent bond

A

bond in which electrons are shared unequally

48
Q

electronegativity

A

the measure of the tendency of an atom to attract electrons to itself in a chemical bond ( that is, to become negative)

49
Q

polar association

A

association that occurs when polar molecules attract and align themselves with other polar molecules and with charged ions and molecules

50
Q

van der waal’s forces

A

weak molecular attractions over short distances

51
Q

molecular geometry

A

the 3-dimensional arrangement of atoms in a molecule, in other words, its shape

52
Q

reactant

A

the atoms or molecules entering a chemical reaction

53
Q

product

A

an atom or molecule leaving a chemical reaction

54
Q

chemical equation

A

a chemical reaction written in balanced form

55
Q

specific heat

A

the amount of heat required to increase the temperature of a given quantity of water

56
Q

cohesion

A

the high resistance of water molecules to separation

57
Q

surface tension

A

the force that places surface water molecules under tension, making them more resistant to separation than the underlying water molecules

58
Q

bilayer

A

a membrane with 2 molecular layers

59
Q

hydration layer

A

a surface coat of water molecules that covers other polar molecules and charged molecules and ions

60
Q

solution

A

substance formed when molecules and ions separate and are suspended individually , surrounded by water molecules

61
Q

solvent

A

the water in a solution in which the hydration layer prevents polar molecules or ions from re-associating

62
Q

solute

A

the molecules of a substance dissolved in water

63
Q

atomic weight

A

the weight of an element in grams, equal to the mass number

64
Q

molecular weight

A

the weight of a molecule in grams, equal to the total mass number of its atoms

65
Q

mole (mol)

A

amount of substance that contains as many atoms or molecules as there are atoms in exactly 12g of carbon-12, which is 6.022 x 10~23

66
Q

dissociation

A

the separation of water to produce positively charged hydrogen ions and hydroxide ions

67
Q

reversible

A

the term indicating that a reaction may go from left to right or from right to left, depending on conditions

68
Q

acid

A

proton donor that releases H+ ions (and anions) when dissolved in water

69
Q

base

A

proton acceptor that reduces the H+ concentration of a solution

70
Q

acidity

A

the concentration of H+ ions in a water solution, compared with the concentration of OH- ions

71
Q

acid precipitation

A

rainfall with low pH, primarily created when gaseous sulfur dioxide (SO2) dissolves in water vapor in the atmosphere, forming sulfuric acid