Biology Exam 1: Chapters 1-4

what is matter

anything that takes up space and has mass

what is matter matter made up of

elements

what is an element

a substance that cannot be broken down to other substances by a chemical reaction

what does a molecule consist of

two or more atoms held together by covalent bonds

what is a compound

substance consisting of two or more elements in a fixed ratio

all compounds are molecules but

not all molecules are compounds

what are the big four elements in the human body

oxygen, carbon, hydrogen, nitrogen

human examples of toxic elements

lead, arsenic, mercury, cadmium

what is an atom

the smallest unit of matter that still remains the properties of an element

what will you find in the nucleus of an atom

protons and neutrons

what do positive protons give the nucleus

a positive charge

what are atoms composed of

subatomic particles

what are subatomic particles

neutrons, protons, electrons

a neutron has

no electrical charge

a electron has

a negative charge

what do atoms of various elements differ in

their number of subatomic particles

what is an elements atomic number

the number of protons in its nucleus

what is an elements mass number

the sum of protons + neutrons in the nucleus

all atoms of an element have the same number of protons but may differ in

the number of neutrons

what are isotopes

two atoms of an element the differ in the number of neutrons

what are radioactive isotopes

they decay spontaneously giving off particles and energy

a “parent” isotope decays into its “daughter” isotope at a fixed rate, expressed as the

half-life of the isotope

what is it called when scientists measure the ratio of different isotopes and calculate how many half-lives have passed since the rock was formed

radiometric dating

what is energy

the capacity to cause change

what is potential energy

the energy that matter possesses because of its location or structure

what does matter have a tendency to do

move toward the lowest possible state of potential energy

what is the chemical behavior of an atom determined by

distribution of electrons in the electron shells

elements with a full valence shell are

chemical inert

what does chemically inert mean

not reactive

atoms with incomplete valance shells can

share or transfer valence electrons with certain other atoms

these interactions usually result in atoms staying close together held by attractions called

chemical bonds

what is a covalent bond

the sharing of a pair of valence electrons by two atoms

what does a molecule consist of

two or more atoms held together by covalent bonds

a single covalent bond is the sharing of

one pair of valence electrons

a double covalent bond is the sharing of

two pairs of valence electrons

what is electronegativity

an atom’s attraction for the electrons in a covalent bond

in a non polar covalent bond

the atoms share an electron

in a polar covalent bond

one atom is more electronegative and the other atoms do not share the electron equally

polar covalent bonds with a water molecule generate

partial negative charge for the oxygen atom and a partial positive charge for the hydrogens

what is a positive charged ion called

a cation

a negatively charged ion is called a

anion

compounds formed by ionic bonds are called

ionic compounds or salts

anions and cations attract each other this attraction is called an

ionic bond

most of the strongest bonds in organisms are

covalent bonds that form a cells molecule

when does a hydrogen bond form

when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom

where are hydrogen bonds found

between water molecules

what are Van Der Waals interactions

attractions between molecules that are closer together as a result of these changes

what determines a molecules shape

the positions of it’s atoms orbitals

what are chemical reactions

the making and breaking of chemical bonds

what are reactants

the starting molecules of a chemical reaction

what are products

the resulting molecules of a chemical reaction

all chemical reactions are

reversible

what to the two opposite headed arrows indicate

that a reaction is reversible

in a water molecule the electrons of a _____ spend more time near the oxygen then the hydrogen

polar covalent bond

what is the overall charge for polar covalent bonds

unevenly distributed

allows water molecules to form hydrogen bonds with each other

polarity

what is it called when hydrogen bonds hold water molecules together

cohesion

what does cohesion result in

high surface tension

what is high surface tension

a measure of how difficult it is to stretch or break the surface of a liquid

what is adhesion

an attraction between different substances

water ____ heat from warmer air and ____ stored heat to cooler air

absorbs and releases

what is kinetic energy

the energy of motion

what is thermal energy

the kinetic energy associated with random motion of atoms or molecules

what does temperature represent

the average kinetic energy of the molecules in a body

what is heat

thermal energy in transfer from one body of matter to another

the calories on food packages are actually

kilocalories (kcal)

what is specific heat

the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1C

waters high specific heat can be traced to

hydrogen bonding

what is evaporation

the transformation of a substance from liquid to gas

what is heat vaporization

the heat of a liquid must absorb 1 g to be converted to gas

what is evaporative cooling

as a liquid evaporates its remaining surface cools

at 0 degrees water molecules are locked into a

crystalline lattice

what is a aqueous solution

when water is the solvent

what is a hydrogen shell

a sphere of water molecules surrounding ion’s in a ionic compound

what is a hydrophilic substance

has an affinity for water

what is a hydrophobic substance

one that does not have an affinity for water

oil molecules are hydrophobic because they have relatively

non polar bonds

what are the major ingredients of cell membranes

hydrophobic molecules related to oils

what is molecular mass

the sum of all masses of all atoms in a molecule

what is molarity (M)

the number of moles of suite per liter of solution

what is a hydrogen ion (H+)

the hydrogen atoms leaves its electron behind and is transferred

what is a hydroxide ion (OH-)

the molecule that lost the proton

what is a hydronium ion (H3O+)

the molecule with an extra proton and is normally written as H+

a change in H+ concentration affect results in what

ph change

concentrations of H+ and OH- are

equal in pure water

what is an acid

a substance that increases the H+ concentration of a solution

what is a base

a substance that reduces the H+ concentration of a solution

what are buffers

substances that minimize changes in concentrations of H+ and OH- in a solution

what is ocean acidification

CO2 dissolved in seawater forms carbonic acid

what is bicarbonate ions

when H+ ions combine with ions

carbon enters biosphere through action of

producers

what molecules are composed of carbon compounds

proteins, dna, and carbohydrates

what do living organisms consist mostly of

carbon based compounds

what is organic chemistry

the study of compounds that contain carbon

what do most organic compounds contain

hydrogen and carbon atoms

what do electron configurations determine

the kinds and numbers of bonds an atom will form with other atoms

what did Stanley millers experiment demonstrate

abiotic synthesis of organic compounds

in molecules with multiple carbons each carbon bonded to four other atoms has a

tetrahedral shape

number of unpaired e in the valence shell is equal to the atoms

valence

from the skeletons of most organic skeletons

carbon chains