Ch. 2 The Nature Of Molecules And The Properties Of Water Flashcards
1
Q
_______ have a nucleus made of _______ and ______ which is surrounded by orbiting ______. The numbers of these particles determine the character of an element.
A
Atoms; protons; neutrons; electrons
2
Q
What’s the charge of each sub-atomic particle? Protons? Neutrons? Electrons?
A
Positive, neutral (no charge), negative
3
Q
Any substance in the universe that has mass and occupies space is defined as ______
A
Matter
4
Q
All matter is composed of extremely small particles called ________
A
Atoms
5
Q
Different atoms are defined by the # of protons, a quantity called the ________ ________
A
Atomic number
6
Q
An _______ is any substance that cannot be broken down to any other other substance by ordinary chemical means
A
Element
7
Q
The ________ of an atom is equal to the sum of the masses of its protons and neutrons.
A
Atomic mass
8
Q
The mass of atoms and subatomic particles is measured in units called _________
A
Daltons
9
Q
Electrons are located in regions called _________ along atom _________
A
Orbitals; shells
10
Q
An atom with an unequal amount of protons and electrons is known as a(n) _______
A
Ion
11
Q
Atoms with more protons than electrons, being positively charged are called ________
A
Cations
12
Q
Atoms with more electrons than protons, being negatively charged are called ______
A
Anions
13
Q
Atoms of a single element with different numbers of neutrons are called _______
A
Isotopes
14
Q
Decay time is expressed as ________
A
Half-life
15
Q
No orbital can contain more than _______ electrons
A
Two
16
Q
The loss of an electron is called ______, the gain of an electron is called _______
A
Oxidation; reduction
17
Q
When oxidation + reduction occur at the same time
A
Redox reactions
18
Q
Electrons on outermost energy level/shell
A
Valence electrons
19
Q
Electrons possessing all eight electrons in their outer most energy level are _______, these elements are known as ________
A
Nonreactive; noble gasses
20
Q
A group of atoms held together by energy is called a ______
A
Molecule
21
Q
Molecules contains atoms of more than one element are called _______
A
Compounds
22
Q
Atoms within molecules are joined by _______
A
Chemical bonds
23
Q
_______ bonds occur when opposite charges attract each other (Na- Cl+)
A
Ionic
24
Q
________ bonds occur when atoms share one or more pair of valence electrons (sharing) H2O
A
Covalent
25
Atoms differ in their affinity for electrons, a property called ________
Electronegativity
26
The strength of covalent bonds is dependent on the number of shared _______
Electrons
27
Bonds between identical atoms, with the affinity for electrons being the same are termed ________
Non polar
28
Atoms that differ greatly in electronegativity, where electrons can not be shared as easily/equally are termed _______
Polar
29
When drawing polar molecules, partial charges are symbolized by the lowercase Greek letter _________
Delta (S)
30
The formation and breaking of chemical bonds is termed a _______
Chemical reaction
31
Original molecules________, result from reaction _________
Reactants; products
32
What 3 factors increase the rate of a reaction?
Heat/Temperature; concentration of reactants/products (more reactants available=more frequent collisions); catalysts i.e. enzymes
33
Many reactions in nature are _______, meaning _________ may also be __________
Reversible; products; reactants
34
How is a covalent bond different from an ionic bond?
An ionic bond results when there is a complete ' ' transfer of electrons between atoms, resulting in positive and negative ions that are attracted to each other. Covalent bonds are the result of two atoms sharing electrons. Polar covalent bonds involve unequal sharing of electrons, producing regions of partial charge. (Draw examples)
35
_________ bonds form between the partially negative O atoms and the partially positive H atoms of two water molecules
Hydrogen Bonds
36
Water likes substances with which it can form hydrogen bonds. _______ is responsible for ___________. (The polarity of water causes it to be attracted to other polar molecules as well)
Adhesion; Capillary action
37
The polarity of WATER allows WATER molecules to be attracted to one another, this property is known as _________. _______ is responsible for __________.
Cohesion; surface tension
38
Hydrogen bonds absorb heat when they break and release heat when they form, minimizing temp changes.
High specific heat
39
Water stabilizes the temp of organisms and the environment
High specific heat
40
Many hydrogen bonds must be broken for water to evaporate
High heat of vaporization
41
Evaporation of water cools body surfaces
High heat of vaporization
42
Water molecules in an ice crystal are spaced relatively far apart because of hydrogen bonding
Lower density of ice
43
Due to the ___________, lakes do not freeze solid, allows fish & other life in lakes to survive the winter
Lower density of ice
44
Polar water molecules are attracted to ions and polar compounds, makings these compounds _________
Soluble; solubility
45
Many kinds of molecules may move freely in cells, permitting a diverse array of chemical reactions
Solubility
46
________ molecules shrink from contact with water. Water molecules act to exclude them.
Hydrophobic; water-hating
47
Polar molecules, which readily form hydrogen bonds with water are considered ________
Hydrophilic; water-loving
48
A _______ is defined as the weight of a substance in grams that corresponds to the atomic masses of all the atoms in a molecule of that substance
Mole
49
The concentration of hydrogen + hydroxide ions in a solution is described using _______
Acidity & basicity
50
The pH scale is________, a difference of 1 on the scale represents a 10-fold change in ___.
Logarithmic; H+
51
Any substance that dissociates in water to increase the ____ & ______ the pH is called an _______
H+; lower; acid
52
Any substance that combines with ____ when dissolved in water, lowering the ____ is called a ______
H+; H+; base
53
The _______ an ______ is, the more _______ ions it produces and the ________ its pH
Stronger; acid; hydrogen; lower
54
A ______ is a substance that resists change in pH.
Buffer
55
_______ act by _________ hydrogen ions when a base is added and __________ hydrogen ions when acid is added, with the overall effect of keeping _______ relatively constant.
Buffers; releasing; absorbing; H+
56
__________ bonds involve unequal sharing of electrons, producing regions of partial charge.
Polar covalent
57
Any substance that has mass + occupies space
Matter
58
All matter is composed of small particles called ______
Atoms
59
At the center ______, made up of _______ + _______
Nucleus;protons;neutrons
60
of protons, otherwise known as ________;
Atomic Number
61
Substance that cannot be broken down to other substance by normal means
Element
62
Proton (_); Electron (_); Electrically neutral if ______
Positive;Negative;Equal
63
Amount of a substance
Mass
64
Force gravity exerts on a substance
Weight
65
Sum of proton + neutron masses
Atomic Mass
66
Mass of atoms & subatomic particles expressed in ______
Daltons
67
Electrons are maintained in their _______ by their attraction to ______ charged nucleus
Orbitals;positively
68
Electrons not equally protons results in formation of
Ions
69
Protons>electrons
Cations (NA+)
70
Protons
Anions(Cl-)
71
Single element with dif # of neutrons results in
Isotopes
72
Unstable, ________ decay -> radioactive ________; decay expressed as ______
Radioactive;isotopes;half-life
73
No orbital can contain more than ______ electrons
Two
74
Atoms contain ________ _______ levels
Discrete;energy
75
Loss of electron = _______
Oxidation
76
Gain of electron =
Reduction
77
Loss & gain of electron =
Redox reaction
78
________ determine the chemical behavior of atoms
Electrons
79
____ of electrons increases as distance from nucleus ________
PE; increases
80
Periodic table based on interactions of _________ in the ________ energy level
Electrons;outermost/valence
81
Chemical behavior reflects how many of the _______ positions are filled
Eight
82
Majority of molecules that make up the body
Organic compounds
83
Elements with filled outermost energy levels are __________
Nonreactive
84
Group of atoms held together by energy
Molecules
85
Molecules with atoms of more than 1 element
Compound
86
Atoms in molecule are joined together by __________
Chemical bonds
87
__________ charges attract eachother = __________
Opposite;ionic bonds
88
Sharing of 1 or more pairs of electrons = ________
Covalent bonds
89
Strength of covalent bond depends on the _________ of shared _________
Number;electrons
90
Atoms differ in their affinity for electron =
Electronegativity
91
Electrons equally shared, similar electronegativity =
Nonpolar
92
Atoms unequally shared, differ greatly in electronegativity
Polar
93
Unequal distribution results in partial _________ charge near the ______ electronegative atom & regions of partial _______ charge near the less electronegative atoms = _______
Negative;more;positive;polar covalent bond
94
Greek letter to represent partial charge
Delta (S)
95
Formation + breaking of chemical bonds =
Chemical reaction
96
Original molecules in reaction =
Reactants
97
Results in chemical reaction =
Products
98
Factors influencing rate of reaction include ______,_______, and ________
Temp/heat;concentration of reactants;catalysts
99
Reactants & products can be ________
Reversible
100
Ionic bonds form _______
Crystals
101
Water facilitates __________ bonding
Hydrogen
102
Waters most important chemical property
Hydrogen Bonding
103
Weak chemical associations between water molecules
Hydrogen bonds
104
H bonds form between partially ________ O atoms and partially _________ H atoms of two water molecules
Negative;positive
105
The _________ of water allows water molecules to be attracted to one another = _________
Polarity;cohesion
106
Oxygen end(_); Hydrogen end(_)
-;+
107
Cohesion is responsible for ___________
Surface tension
108
Surface water molecules hydro bonded to molecules below them
Surface tension
109
Polarity allows water to be attracted to other polar molecules
Adhesion
110
Adhesion is responsible for __________
Capillary action
111
NaCl ________ with water due to water ability to form ________ bond with _________ molecules
Dissolves;hydrogen;polar
112
Water is the _______; sugar/table salt is the _______
Solvent;solute
113
Water molecules surround NaCl ions; prevents it from association with other sucrose materials
hydration shell
114
Water moderates _______ through 2 properties, ________ & _________
Temperature;high specific heat; heat of vaporization
115
1g of substance must absorb or lose to change its temp by 1C
High specific heat
116
Property that allows organisms to maintain a relatively constant internal temp
High specific heat
117
Amount of energy required to change 1g of a substance from a liquid to a gas
Heat of vaporization
118
Property responsible for sweating/evaporative cooling
Heat of vaporization
119
________ water is less dense than ______ water
Solid;liquid
120
Property responsible for ice floating, fish + animals from freezing
Ice less dense than liquid water
121
Water molecules gather ________ around any substance that bears an _________ charge
Closely;electrical
122
________ molecules ie. _____, are unable to form hydrobonds when placed in water
Non polar;oils
123
Water molecules act to exclude, non polar molecules aggregate/clump together
Hydrophobic
124
Polar molecules readily form _______ bonds = ________
Hydrogen;Hydrophilic
125
Concentration of hydrogen ions + hydroxide ions =
Acidity & basicity
126
Ph scale is _______, dif of 1 on scale is ________fold
Logarithmic;10fold
127
Any substance that dissociates in water to ___________ the H+ and _______ the pH is a(n)
Increase;lower;acid
128
Stronger the acid, ______ H+ is produces and _______ its pH
more;lower
129
A substance that ________ with H+ in water to _________ its own H+ is a _________
Combines;lower;base
130
Substance that resists pH change
Buffer
131
Release H+ for _____
Bases
132
Absorb H+ for ______
Acids
133
Tendency of non polar molecules to aggregate is known as _________
Hydrophobic exclusion
134
Spontaneous ion formation of water
Ionization
135
Weight of a substance in g; cooresponds to atomic mass of all atoms in a substance
Moles
136
When 2 atoms with different electronegative potentials engage in a covalent bond, it will result in a ________ charge
Partial
137
_>_>_=_
O;N;C;H
138
Why do water molecules stick to eachother
Water molecules are polar so the partially negative Oxygens are attracted to the partially positive Hydrogens
139
Weak association found with hydrogen in polar covalent bonds
Hydrogen bonds
140
In water, partially ________ Hydrogen is associated with partially _______ Oxygen; little _______
Positive;negative;magnets
141
Hydrogen bonds are _________ ________ bonds
Weak transient
142
Why is water a good solvent?
It’s ability to form hydrogen bonds with other molecules, ability to make weak associates, associate with other molecules
143
If something is soluble in water….
It can form a hydrogen bond
144
Why can’t oil dissolve in water?
Oil is hydrophobic, inability to form hydrogen bonds
145
Molecules that have charges that can form hydrogen bonds
Hydrophilic, water loving
146
Molecules that lack charges and cannot form hydrogen bonds
Hydrophobic
147
Electronegativity differs -> ______ charges -> ability to ______ ______ bonds
Partial;form;hydrogen
148
Bonding between unlike molecules, ex. _______
Adhesion;capillary action
149
Bonding between like molecules, ex. ________
Cohesion;surface tension
150
Density - ______>______>______
Water;ice;water vapor
151
Why is ice less dense?
Water molecules with ice crystalline matrix are further in distance from one another than in liquid water
152
What is an ionic bond?
Two atoms held together through opposite charges gained via the movement/transfer of an electron from one atom to another
153
What is a molecule?
Group of atoms bonded together, most fundamental unit of a chemical compound
154
What are the relative electronegativities of the four most abundant atoms found in living things?
155
What partial charge would be created by the exposed protons from the hydrogens?
Partial Positive
156
What partial charge would be created by the exposed electron pairs from the oxygen
Partial negative
157
What Greek letter is used to denote partial charges created by electronegativity?
Delta (S)
158
Why does table salt readily dissolve in water?
The negative Cl- is attracted to the positively charged Hydrogen atom of a water molecule, with the Na+ being attracted to the negatively charged Oxygen atom of the molecule
159
What property of water molecules makes it a solvent
Waters partial positive and negative charges determine its polarity, and its polarity along with its ability to form hydrogen bonds and break substances down makes it a good solvent
160
What is molecular cohesion and how does it relate to water?
Molecular cohesion is the attraction between the same kinds of molecules, water is strongly cohesive due to its ability to hydrogen bond.
161
What is molecular adhesion and how does it related to water?
Molecular adhesion is the attraction to different kinds of molecules, and water possesses this property due to its polarity
162
Why is oil insoluble in water?
Oils and fats are non polar so they are unable to break the hydrogen bonds of water. This causes the oil to stay separate and exclude itself from the water.
163
H+Cl- is the formula for hydrochloric acid. Why would this molecule make an acidic solution?
Hydrochloric acid is held together by ionic bonds and when placed into water, breaks away to form hydrogen ions, resulting in an acidic liquid. HCl has a very low pH, thus is very acidic.
164
H2O + H+Cl- -> _____ + _____
H3O+;Cl-
165
Na+OH- is the formula for sodium hydroxide, a strong base. What makes this molecule basic?
Sodium hydroxide is a strong base because it dissociates entirely in water to form sodium cations an hydroxide anions. The hydroxide anions make this solution a strong base.
166
If you add lemon to your tea how is the pH affected?
Lemon juice is acidic, so in adding lemon to your tea would lower its pH.
167
How does adding lemon to tea affect the proton/hydronic content of the tea?
Lemon juice is highly acidic thus having a very high amount of hydrogen ions. Adding lemon to your tea would not only lower its pH, but increase its H+ ions and concentration as well.
168
If you add milk to coffee, how is the pH of the coffee affected?
The pH of coffee is raised due to milks higher pH, making it slightly less acidic and more basic
169
How does adding milk to coffee affect the proton/hydronic content of the coffee?
Adding milk to coffee lowers the concentration of H+ ions in the coffee ….
170
If a proton attaches to water it forms a ________
Molecule
171
A molecule defined as a base removes _______ from a solution
Hydrogen ions
172
A molecule defined as an acid adds excess ______ to a solution
Hydrogen ions
173
PH is determined by the concentration of _______ in a solution
Hydrogen ions
174
What is a covalent bond?
Two atoms held together because they share a pair of electrons
175
What is a molecule?
Two or more atoms held together by a covalent bond
176
What is a hydrogen bond?
The electrostatic interaction between the partial positive charge of an exposed proton (hydrogen) in one molecule and the partial negative charge of outer shell electrons in the other
177
What is an ionic bond?
A transfer of electrons between oppositely charged attracted atoms
178
Why does table salt readily dissolve in water?
The full charges of the Na+ and Cl- attract the partial charges found on the water molecule
179
What property of water molecules makes it a solvent?
It’s ability to form hydrogen bonds with charged or partially charged atoms
180
What is a hydrophilic molecule?
A molecule with a partial or full charge that is attracted to water
181
What is a hydrophobic molecule?
A neutral molecule that is not attracted to water
182
What is molecular cohesion and how does it relate to water?
The attraction of like molecules to one another & water molecules are attracted to one another by way of partial charges
183
What is molecular adhesion and how does it relate to water?
The attraction of unlike molecules to one another, water molecules are attracted to any molecules with a full or partial charge, other polar molecules
184
Which is more dense and why, water vapor, water, or ice?
Liquid water is more dense than solid ice or water vapor because the molecules of liquid water are closer than those of ice or vapor
185
Why is oil insoluble in water?
Oil is a neutral molecule so there are no charges for water to attach
186
Why did we start a biology class by reviewing basic chemistry?
Living things themselves are made up of chemical composition. Our survival is dependent on the chemical reactions taking place inside our bodies.
187
Explain one way a covalent bond differs from a hydrogen bond
Covalent bonds differ in that they are sharing chemical bonds that are found due to the sharing of electrons between atoms, whereas hydrogen bonds are weak bonds formed by the partial attractions between H & O atoms of water molecules.
188
Explain why water has partial charges even though the molecule has a net equal number of electrons and protons, i.e. the overall charge of the molecule is neutral.
While water does have an equal number of electrons and protons, due to a difference in electronegativity, the electrons are unequally shared which results in these partial positive and partial negative charges seen with H and O.
189
Explain the role of hydrogen bonding in creating the properties of liquid water
Hydrogen bonds cause water to be strongly attracted to other water molecules, which gives way for its cohesive property and water being the ultimate solvent, being able to form hydrogen bonds with like molecules.
