Ch. 2 The Chemical Context Of Life

Front 1

Matter

Back 1

Anything that takes up space and has mass

Front 2

Element

Back 2

A substance that cannot be broken down to other substances by chemical reactions

Front 3

Compound

Back 3

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

Front 4

Essential Elements

Back 4

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

Front 5

Trace Elements

Back 5

Required by an organism in only minute quantities

Front 6

Atom

Back 6

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

Front 7

Neutrons

Back 7

Electrically nutral subatomic particle

Hint 7

Atoms are divided up into subatomic particles

Front 8

Protons

Back 8

Positively charged subatomic particle

Front 9

Electrons

Back 9

Negatively charged subatomic particle

Front 10

Atomic Nucleus

Back 10

A dense core at the center of an atom

Front 11

Dalton

Back 11

Unit of measurement that is 1.7×10^-24 grams. Also called atomic mass unit

Front 12

Atomic Number

Back 12

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

Front 13

Mass Number

Back 13

The sum of protons plus neutrons in the nucleus of an atom

Front 14

Atomic Mass

Back 14

The total mass of an atom, which is the mass in grams of 1 mole of the atom

Front 15

Isotopes

Back 15

An atomic form of an element, each with the same number of protons but a different number of nuetrons, thus differing in atomic mass

Front 16

Radioactive Isotope

Back 16

Isotope in which the nucleus decays spontaneously, giving off particles and energy

Front 17

Energy

Back 17

The capacity to cause change

Front 18

Potential Energy

Back 18

The energy that matter possesses because of its location or structure

Front 19

Electron Shells

Back 19

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

Front 20

Valence Electrons

Back 20

Electrons in outermost shell

Front 21

Valence Shell

Back 21

Outermost electron shell

Front 22

Chemical Bonds

Back 22

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

Front 23

Covalent Bond

Back 23

The sharing of a pair of valence electrons by two atoms

Front 24

Molecule

Back 24

Two or more atoms held together by covalent bonds

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Single Bond

Back 25

A pair of shared electrons

Front 26

Double Bond

Back 26

Two pairs of shared electrons

Front 27

Valence

Back 27

The bonding capacity of a given atom; the number of covalent bonds an atom can form usually equals the number of unpaired electrons in its outermost shell

Front 28

Electronegativity

Back 28

The attraction of a particular atom for the electrons of a covalent bond

Front 29

Nonpolar Covalent Bond

Back 29

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

Front 30

Polar Covalent Bond

Back 30

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

Front 31

Ion

Back 31

A charged atom or molecule

Front 32

Cation

Back 32

A positively charged ion

Front 33

Anion

Back 33

A negatively charged ion

Front 34

Ionic Bond

Back 34

A chemical bond resulting from the attraction between oppositely charged ions

Front 35

Ionic Compounds (salts)

Back 35

Compounds formed by ionic bonds

Front 36

Hydrogen Bond

Back 36

Noncovalent attraction between a hydrogen and an electronegative atom

Front 37

Van Der Waals Interactions

Back 37

Weak attractions between molecules or parts of molecules that results from transient local partial charges

Front 38

Reactant

Back 38

A starting material in a chemical reaction

Front 39

Product

Back 39

A material resulting from a chemical reaction

Front 40

Chemical Equilibrium

Back 40

The point at which the reactions offset one another exactly

Front 41

Polar Molecule

Back 41

A molecule with an uneven distribution of charges in different regions of the molecule

Front 42

Cohesion

Back 42

The linking together of like molecules, often by hydrogen bonds

Front 43

Adhesion

Back 43

The clinging of one substance to another

Front 44

Surface Tension

Back 44

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

Front 45

Kinetic Energy

Back 45

The energy of motion

Front 46

Thermal Energy

Back 46

The kinetic energy associated with the random movement of atoms or molecules

Front 47

Temperature

Back 47

The average kinetic energy of the molecules, regardless of volume

Front 48

Heat

Back 48

Thermal energy in transfer from one body of matter to another

Front 49

Calorie (cal)

Back 49

The amount of heat it takes to raise the temperature of 1g of water by 1°C

Front 50

Kilocalorie (kcal)

Back 50

1,000 cal, the quantity of heat required to raise the temperature of 1 kilogram (kg) of water by 1°C

Front 51

Joule (J)

Back 51

An energy unit. One joule equals 0.239 cal; one calorie equals 4.184 joule

Front 52

Specific Heat

Back 52

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

Front 53

Heat of Vaporization

Back 53

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

Front 54

Evaporative Cooling

Back 54

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

Front 55

Solution

Back 55

A liquid that is a completely homogeneous mixture of two or more substances

Front 56

Solvent

Back 56

The dissolving agent of a solution

Front 57

Solute

Back 57

The substance that is dissolved in a solution

Front 58

Aqueous Solution

Back 58

Solution in which water is the solvent

Front 59

Hydration Shell

Back 59

The sphere of water molecules around each disolved ion

Front 60

Hydrophilic

Back 60

Any substance that has an affinity for water

Front 61

Hydrophobic

Back 61

Having no affinity for water

Front 62

Molecular Mass

Back 62

The sum of the masses of all the atoms in the molecule

Front 63

Mole (mol)

Back 63

The number of grams of a substance that equals its molecular weight in daltons and contains Avogadro's number (6.02×10^23) of molecules

Front 64

Molarity

Back 64

The number of moles of solute per liter of solution

Front 65

Hydrogen Ion (H+)

Back 65

A single proton with a charge of 1+

Front 66

Hydroxide Ion (OH-)

Back 66

A single proton with a charge of 1-

Front 67

Hydronium Ion (H3O+)

Back 67

A water molecule that has an extra proton bound to it

Front 68

Acid

Back 68

A substance that inctreases the hydrogen ion concentration of a solution

Front 69

Base

Back 69

A substance that reduces the hydrogen ion concentration of a solution

Front 70

pH

Back 70

The negative logarithm (base 10) of the hydrogen ion concentration ranging in value from 0 to 14

Front 71

Buffer

Back 71

A substance that minimizes changes in the concentrations of H+ and OH- in a solution