BIOL152 Chapter 2
Cohesion
Water molecules stick to other water molecules through hydrogen bonding.
Water has a high specific heat
A large amount of energy is required to change the temperature of water. Why is this?
Kinetic Energy
Movement
Protons
Positively charged particles located in the nucleus.
Covalent bond Ionic bond Hydrogen bond Hydrophobic interaction Van der Waals attraction
Rank following from strongest to weakest -Ionic bond -Van der Waals interaction -Hydrophobic interaction -Hydrogen bond -Covalent bond
Terpenes
Some are components of important biological pigments.
Steroids
Some function as hormones in animals.
True
True/False In pure water, the concentration of hydrogen ions always equals the concentration of hydroxide ions.
False
True/False Breaking the hydrogen bond between two water molecules is called dissociation.
False, Oxygen
True/False Of the four most common elements found in living organisms, nitrogen has the highest electronegativity and, therefore, the greatest affinity for electrons.
True
True/False The hydroxide ion has an overall charge of -1.
increases
As the hydrogen ion concentration of a solution decreases, the pH _________
increases
As the pH of a solution increases, the concentration of hydroxide ions _________
Isotopes
Atoms of a single element that posses different numbers of neutrons.
Octet Rule
Atoms tend to establish completely full outer energy levels.
Ions
Atoms that have gained or lost electrons and therefore are no longer electrically neutral are called _____
Ions
Charged particles, unbalanced.
Concentration of a neutral aqueous solution
pH=1 x 10^-7
Mole
1 ______ = 6.02× 10^23 molecules
Acid
Any substance that increases the H+ concentration of a solution.
Basic solutions pH
Greater than 7
Compounds
Molecules containing more than one type of element.
1 x 10^-14
[OH-][H+]
Hydrophobic substance tend to do what?
-Be repelled by water -Assume shapes to minimize contact with water -Aggregate together when mixed with water in order to minimize contact with water
Ionic Bonds
A bond formed by the attraction of oppositely charged ions.
Aqueous solution
A solution in which water is the solvent.
Electronegativity
An atom's affinity for electrons.
Key components in human blood that maintain pH
Bicarbonate: reduces number of H+ when an acid is added Carbonic acid: increases number of H+ when a base is added
Isotopes
C-12, C-13, and C-14 have the same number of protons but different numbers of neutrons so they are ______________
Temperature Concentration of reactants/products Catalysts
Extent of chemical reactions are influenced by what three factors?
Anion
Fewer protons than electrons=net negative charge.
Covalent Bonds
Form when atoms share 2 or more valence electrons. -no net charge -satisfies octet rule -no unpaired electrons
Molecules
Groups of atoms held together in a stable association.
Hydronium Ion
H3O+, The water molecule that gains the extra proton.
Inert (non-reactive) elements
Have all eight electrons.
They are highly directional
Hydrogen bonds can help maintain the structures of large biological molecules because....
Denatured
If the interactions that maintain the 3-dimensional shape of a protein are disrupted so that the polypeptide chain completely unfolds it is described as....
List water states from most dense to least dense
Liquid, Solid, Gas
AT GC
Match the bases that pair in DNA Adenine Thymine Guanine Cytosine
Products
Molecules resulting from a reaction.
Cation
More protons than electrons=net positive charge.
pH
Negative logarithm of H+ concentrations, or ___=-log[H+]
Electrons
Negatively charged particles located in orbitals surrounding the nucleus.
Neutrons
Neutral particles located in the nucleus.
Electrons
Number of protons equals number of _________.
Hydroxide Ion
OH-, The water molecule that loses the proton.
Potential Energy
Stored energy based on position.
Compound
Substance consisting of two or more elements in a fixed ratio.
Element
Substance that cannot be broken down to other substances by chemical reactions.
Buffers
Substances that minimize changes in concentrations of H+ and OH- in a solution.
Atomic Mass
Sum of an elements protons and neutrons.
Oxygen, Carbon, Hydrogen, Nitrogen, Calcium, Phosphorus, Sulfur, Potassium, Sodium, Chlorine, Magnesium, Iron
The 12 elements found in living organisms in substantial amounts.
Water has a high heat of vaporization
The evaporation of water from a surface causes cooling of that surface.
Phospholipids
The main component of cell membranes.
negative logarithm
The pH of a solution is defined as the ____________________________ of the hydrogen ion concentration.
Solute
The substance that is dissolved in a solution.
Molecular mass
The sum of all masses of all atoms in a molecule.
False, The hydrogen atom can move back and forth between the two molecules.
True/False A hydrogen atom in a hydrogen bond between two water molecules cannot move again, and stays in the same position.
False
True/False Although C and H differ slightly in electronegativity, this small difference is negligible, and C-H bonds are considered polar.
False, affinity for electrons
True/False Atoms differ in their affinity for neutrons, a property called electronegativity.
True
True/False Most chemical reactions in organisms involve solutes dissolved in water.
Polar covalent bonds
Unequal sharing of electrons. (EX: Water)
Dynamic equilibrium, Same rate
Water is in a state of __________ _______________ in which water molecules dissociate at the _____ _____ at which they are reformed.
Adhesion
Water molecules stick to other polar molecules by hydrogen bonding
Polarity
What causes the dissolving of certain things in water?
Oxidation
Which loses an electron thus becoming more positively charged, a reduction or an oxidation?
Acidic solutions pH
Less than 7
True
True/False A water molecule is held together by two single polar covalent bonds.
True
True/False Concentrations of H+ and OH- are equal in pure water.
Energy levels
-Often drawn as circles around the nucleus -Consist of one or more orbitals -Indicate an electron's relative distance from the nucleus -Indicate the amount of potential energy an electron contains
Water molecules are attracted to...
-Other water molecules -Ions -Polar molecules -Substances that bear an electrical charge
Solution
A liquid that is a completely homogeneous mixture of substances.
Base
Any substance that reduces the H+ concentration of a solution.
Nonpolar, hydrophobic
Characteristics shared by all lipids.
pH scale
Describes whether a solution or compound is acidic or basic.
Hydrogen Ion
H+, The proton transferred from one water molecule to another.
Atoms
Held together in molecules or compounds by chemical bonds.
Amino Acids
Proteins are made up of one or more unbranched chains of...
Specific Heat
The amount of heat 1g of a substance must absorb to change its temperature by 1 C
Solvent
The dissolving agent of a solution.
Molarity
The number of moles of solute per liter of solution. (PAGE 4 of notes slide 1)
Phospholipids
They have a polar head and two nonpolar tails.
1.False 2.False 3.True
True/False 1. Most matter is composed of atoms but some is not. 2. Solid, and liquid matter is composed of atoms while gaseous matter is not. 3. All matter is composed of atoms.
True
True/False A covalent bond is formed when two atoms share one or more pairs of electrons.
A polar or ionic region
What does water need to be able to dissolve a protein?
Hydration Shell
When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules. What is this sphere called?
Fats
long-term energy storage.
Hydrophobic
"Water-fearing". Substance that does not have an affinity for water.
Hydrophilic
"Water-loving". Substance that has an affinity for water
Valence Electrons
Number of electrons in outermost energy level.
True
True/False Water dissociates into oppositely charged ions.
True
True/False When a hydrogen ion separates from a water molecule, it usually combines with another water molecule to form a hydronium ion.
Weight
Refers to the force gravity exerts on a substance.
Radioactive Isotopes
Unstable and emit radiation as the nucleus breaks up.
a large amount of energy is required to break the many hydrogen bonds that restrict the movement of individual water molecules.
Water boils at a higher temperature than a nonpolar solvent like ether because
Water organizes nonpolar molecules
Water causes hydrophobic molecules to aggregate or assume specific shapes.
Water is a good solvent
Water dissolves polar molecules and ions.
b and d
Water interacts with polar substances like -OH groups but not with nonpolar substances like methyl (-CH3) or ethyl groups (-CH2). Using this information, select the molecules that will easily dissolve in water based on polarity not on size. Check all that apply. Check All That Apply a) CH4 b) CH3OH c) CH3 CH3 d) CH3 CH2 CH2 OH e) CH3 CH2 CH2 CH2 CH2 CH3
Bohr Model
-Electrons in discrete orbits -Orbitals can't contain more than two electrons
Hydrogen Bonds
-Electropositive hydrogen from one polar molecule is attracted to electronegative atom that is often oxygen -Weak, transitory bonds -Responsible for water's many important physical properties
buffer
A(n) ______ acts to maintain a relatively stable concentration of hydrogen ions in a solution.
base
A(n) __________ acts to decrease the hydrogen ion concentration of a solution.
acid
A(n) ____________ acts to increase the hydrogen ion concentration of a solution.
Matter
Anything that takes up space and has mass.
Orbital
Area around nucleus where electrons are most likely to be located.
decreases
As the hydrogen ion concentration of a solution increases, the pH __________
ions
Atoms that have gained or lost electrons and are no longer electrically neutral are called _______
Solid water is less dense than liquid water
Bodies of water freeze from the top down.
element
C-12, C-13, and C-14 all have the same number of protons and are the same _________________
Further
Electrons (further/closer) to the nucleus have more energy.
Nonpolar covalent bonds
Equal sharing of electrons.
Fasle
True/False When water dissociates, an oxygen atom separates from the rest of the molecule.
The same
In a neutral atom atoms have ____________ number of electrons and protons.
Chemical Reactions
Involve the formation or breaking of chemical bonds
Reactants
Original molecules in a reaction.
Redox Reaction
Oxidation Reduction Reaction
Chemical Equilibrium
Reached when the forward and reverse reactions occur at the same rate.
Mass
Refers to the amount of substance.
1 Dalton
The approximate mass of a single neutron or a single proton.
six
The atomic number of carbon-13 is _______
True
True/False Within a water molecule, the bonds between oxygen and hydrogen are highly polar. Oxygen is much more electronegative than Hydrogen (partial electrical charges develop).
Carbon, Hydrogen, Oxygen, Nitrogen
The four elements that make up 96.3% of human body weight.
protons
The nucleus of an atom always contains one or more ___________
Atomic Number
The number of protons that describes an elements atoms.
electrons
The orbitals of an atom contain negatively charged particles called _____________
True
True/False Polar molecules are electrically neutral, but the distribution of charge within the molecule is not uniform.
Half-life
Time it takes for one-half of the atoms in a sample to decay.
True
True/False In a nonpolar covalent bond there is an equal sharing of electrons between two atoms while polar covalent bonds involve an unequal sharing of electrons.
False, 1x10^-7
True/False In pure water, the concentration of hydrogen ions is 1 x 10^7 molar.
False, the more electrons shared the stronger the bond
True/False A covalent bond with one pair of shared electrons is stronger than a bond with 3 pairs of shared electrons.
True
True/False A hydrogen ion is the same as a proton.
False, H3O+
True/False A hydronium ion has the formula H2O+.
False
True/False A single molecule of oxygen (O2) is held together by two double nonpolar covalent bonds.
True
True/False A slightly positive hydrogen atom on one water molecule can attract the slightly negative oxygen atom on a different water molecule, leading to the formation of a hydrogen bond.
True
True/False Because oxygen has a greater electronegativity than hydrogen, water molecules are polar with two partial negative charges near the oxygen atom and one partial positive charge near each hydrogen atom.
False, 3-dimensional
True/False Electrons are only orbiting nucleus in a single 2-dimensional path.
True
True/False Every atom of a particular element has the same number of protons.
False, increases up and to the right
True/False In general, electronegativity increases from left to right across each row of the periodic table and also increases down each column.
False
True/False In pure water, at 25°C, about 10% of the water molecules are dissociated at any given time.
False, the oxygen is δ- and the hydrogen is δ+
True/False In water the polarity causes Oxygen to be partially positive δ+, and Hydrogen to be partially negative δ-.
Electrical attraction of water molecules
What can disrupt the forces holding ions together?
Number of shared electrons
What does the strength of a covalent bond depend on?
Reduction
Which gains an electron thus becoming more negatively charged, a reduction or an oxidation?
Water transport in plants, since water is able to attach to itself and to other polar molecules it is able to travel upwards through plants, supplying them with water.
Why are cohesion and adhesion of water molecules important in life?