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?