[2] Vocabulary - The Chemical Context of Life

Question 1

cation

Answer 1

a positively charged ion

Question 2

scatter plot

Answer 2

a graph in which each piece of data is represented by a point, but individual points are not connected by lines

Question 3

solution

Answer 3

homogenous mixture of two or more substances

Question 4

chemical equilibrium

Answer 4

rate of forward reaction equals rate of reverse reaction, concentrations of reactants and products do not change over time

Question 5

anion

Answer 5

a negatively charged ion

Question 6

proton

Answer 6

a subatomic particle with a single positive electrical charge (mass approximately 1.7x10^-24 grams)

Question 7

atomic number

Answer 7

the number of protons in the nucleus of an atom, unique for each element and designated by a subscript

Question 8

mass number

Answer 8

the total number of protons and neutrons in an atom’s nucleus

Question 9

chemical reaction

Answer 9

the making and breaking of chemical bonds, leading to changes in the composition of matter

Question 10

matter

Answer 10

anything that takes up space and has mass

Question 11

energy

Answer 11

the capacity to cause change, especially to do work (to move matter against an opposing force)

Question 12

compound

Answer 12

a substance consisting of two or more different elements combined in a fixed ratio

Question 13

trace element

Answer 13

an element indispensable for life but required in extremely minute amounts

Question 14

pH

Answer 14

a measure of hydrogen ion concentration equal to -log[H+] and ranging in value from 0 to 14.

Question 15

polar molecule

Answer 15

a molecule (such as water) with an uneven distribution of charges in different regions of the molecule

Question 16

temperature

Answer 16

a measure in degrees of the average thermal energy of the atoms and molecules in a body of matter

Question 17

atomic mass

Answer 17

mass of an atom, equal to mass in grams of 1 mole

Question 18

essential element

Answer 18

A chemical element required for an organism to survive, grow, and reproduce.

Question 19

acid

Answer 19

substance that increases hydrogen ion concentration (pH=0-6.9)

Question 20

evaporative cooling

Answer 20

The process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest kinetic energy changing from the liquid to the gaseous state.

Question 21

regression line

Answer 21

a line that best describes the behavior of a set of data

Question 22

ocean acidification

Answer 22

The process by which the pH of the ocean is lowered (made more acidic) when excess CO2 dissolves in seawater and forms carbonic acid (H2CO3).

Question 23

thermal energy

Answer 23

Kinetic energy due to the random motion of atoms and molecules; energy in its most random form.

Question 24

ionic bond

Answer 24

a chemical bond resulting from the attraction between oppositely charged ions.

Question 25

electron

Answer 25

a subatomic particle with a single negative electrical change and a mass about 1/2000 that of a neutron or proton. One or more electrons move around the nucleus of an atom.

Question 26

mole (mol)

Answer 26

The number of grams of a substance that equals its molecular weight in daltons and contains Avogadro’s number of molecules.

Question 27

hydrogen ion

Answer 27

the cation H+ of acids consisting of a hydrogen atom whose electron has been transferred to the anion of the acid

Question 28

ionic compound

Answer 28

A compound resulting from the formation of an ionic bond; also called a salt.

Question 29

kinetic energy

Answer 29

the energy associated with the relative motion of objects--moving matter can perform work by imparting motion to other matter

Question 30

hydrogen bond

Answer 30

a type of weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule

Question 31

reactant

Answer 31

a starting material in a chemical reaction

Question 32

base

Answer 32

a substance that reduces the hydrogen ion concentration of a solution, a substance with a high pH

Question 33

valence electron

Answer 33

an electron in the outermost electron shell

Question 34

adhesion

Answer 34

the clinging of one substance to another, such as water to plant cell walls, by means of hydrogen bonds

Question 35

buffer

Answer 35

a solution that contains a weak acid and its corresponding base to minimize changes in pH when acids or bases are added to the solution

Question 36

nonpolar covalent bond

Answer 36

a type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity

Question 37

polar covalent bond

Answer 37

A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.

Question 38

element

Answer 38

any substance that cannot be broken down to any other substance by chemical reactions

Question 39

specific heat

Answer 39

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

Question 40

neutron

Answer 40

a subatomic particle having no electrical charge (electrically neutral) with a mass of about 1.7 x 10-24g, found in the nucleus of an atom

Question 41

molecular mass

Answer 41

the sum of the masses of all the atoms in a molecule; sometimes called molecular weight

Question 42

product

Answer 42

a material resulting from a chemical reaction

Question 43

valence

Answer 43

the bonding capacity of a given atom; the number of covalent bonds an atom can form, which usually equals the number of unpaired electrons in its outermost (valence) shell

Question 44

salt

Answer 44

a compound resulting from the formation of an ionic bond; also called an ionic compound

Question 45

surface tension

Answer 45

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

Question 46

molecule

Answer 46

two or more atoms held together by covalent bonds

Question 47

radioactive isotope

Answer 47

an isotope (an atomic form of a chemical element) that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy

Question 48

chemical bond

Answer 48

an attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells.

Question 49

hydrophilic

Answer 49

having an affinity for water

Question 50

molarity

Answer 50

a common measure of solute concentration, referring to the number of moles of solute per liter of solution

Question 51

kilocalorie

Answer 51

a thousand calories; the amount of heat energy required to raise the temperature of 1 kg of water by 1 C

Question 52

electron shell

Answer 52

an energy level of electrons at a characteristic average distance from the nucleus of an atom

Question 53

hydroxide ion

Answer 53

a water molecule that has lost a proton; OH-

Question 54

covalent bond

Answer 54

a type of strong chemical bond in which two atoms share one or more pairs of valence electrons

Question 55

van der Waals interactions

Answer 55

weak attractions between molecules or parts of molecules that result from transient local partial charges

Question 56

heat of vaporization

Answer 56

the quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state

Question 57

hydration shell

Answer 57

the sphere of water molecules around a dissolved ion

Question 58

ion

Answer 58

an atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge

Question 59

joule

Answer 59

a unit of energy: 1 J = 0.239 cal; 1 cal = 4.184 J

Question 60

electronegativity

Answer 60

the attraction of a given atom for the electrons of a covalent bond

Question 61

solvent

Answer 61

the dissolving agent of a solution. Water is the most versatile solvent known

Question 62

hydrophobic

Answer 62

having no affinity for water; tending to coalesce and form droplets in water

Question 63

atomic nucleus

Answer 63

an atom's dense central core, containing protons and neutrons

Question 64

valence shell

Answer 64

the outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom

Question 65

heat

Answer 65

thermal energy in transfer from one body of matter to another

Question 66

dalton

Answer 66

a measure of mass for atoms and subatomic particles; the same as the atomic mass unit, or amu

Question 67

potential energy

Answer 67

the energy that matter possesses as a result of its location or spatial arrangement (structure)

Question 68

cohesion

Answer 68

the linking together of like molecules, often by hydrogen bonds

Question 69

atom

Answer 69

the smallest unit of matter that retains the properties of an element

Question 70

double bond

Answer 70

a double covalent bond; the sharing of two pairs of valence electrons by two atoms

Question 71

solute

Answer 71

a substance that is dissolved in a solution

Question 72

isotope

Answer 72

one of several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing in atomic mass

Question 73

single bond

Answer 73

a single covalent bond; the sharing of a pair of valence electrons by two atoms

Question 74

aqueous solution

Answer 74

a solution in which water is the solvent

Question 75

calorie (cal)

Answer 75

The amount of heat energy required to raise the temperature of 1 g of water by 1°C; also the amount of heat energy that 1 g of water releases when it cools by 1°C. The Calorie (with a capital C), usually used to indicate the energy content of food, is a kilocalorie.

Question 76

hydronium ion

Answer 76

a water molecule that has an extra proton bound to it; H3O+, commonly represented as H+