Chapter 2: Water and Carbon: The Chemical Basis of Life

Question 1

valence shell

Answer 1

the outermost electron shell of an atom

Question 2

cation

Answer 2

a positively charged ION

Question 3

organic

Answer 3

for a compound, containing carbon and hydrogen and usually containing carbon-carbon bonds. organic compounds are widely used by living organisms.

Question 4

surface tension

Answer 4

the cohesive force that causes molecules at the surface of a liquid to stick together, thereby resisting deformation of the liquid’s surface and minimizing its surface area.

Question 5

nonpolar covalent bond

Answer 5

a covalent bond in which electrons are equally shared between two atoms of the same electronegativity.

Question 6

space-filling model

Answer 6

a representation of a molecule where atoms are shows as balls–color coded and scaled to indicate the atom’s identity–attached to each other in the correct geometry.

Question 7

valence

Answer 7

the number of unpaired electrons in the outermost electron shell of an atom; often determines how many covalent bonds the atom can from.

Question 8

hydrophobic interactions

Answer 8

“fear of water” very weak interactions between nonpolar molecules, when exposed to an aqueous solvent.

Question 9

heat

Answer 9

thermal energy that is transferred from an object at higher temperature to one at lower temperature

Question 10

temperature

Answer 10

a measurement of thermal energy present in an object or substance, reflecting how much the constituent molecules are moving

Question 11

thermal energy

Answer 11

the kinetic energy of molecular motion

Question 12

atomic weight

Answer 12

average mass of an element that is based on the relative proportions of all the naturally occuring isotopes

Question 13

adhesion

Answer 13

the tendency of certain dissimilar molecules to cling together due to attractive forces

Question 14

buffer

Answer 14

a substance that, in solution, acts to minimize changes in the pH of that solution when acid or base is added

Question 15

solvent

Answer 15

any liquid in which one or more solids or gases can dissolve

Question 16

potential energy

Answer 16

energy stored in matter as a result of its position or molecular arrangement. compare with kintetic energy

Question 17

atomic number

Answer 17

number of protons in the nucleus of an atom, giving the atom its identity as a particular chemical element

Question 18

covalent bond

Answer 18

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

Question 19

isotope

Answer 19

any of several forms of an element that have the same number of protons but different number of neutrons.

Question 20

catalyst

Answer 20

any substance that increases the rate of chemical reaction without itself undergoing any permanent chemical change

Question 21

hydrophilic

Answer 21

“water loving” interacting readily with water and are typically polar compounds containing partially charged atoms

Question 22

electron shell

Answer 22

group of orbitals of electrons with similar energies. they are arranged in roughly concentric layers around the nucleus of an atom

Question 23

hydrogen bond

Answer 23

weak interaction between two molecules or different parts of the same molecule resulting from the attraction between a hydrogen atom with a partial positive charge and another with a partial negative charge

Question 24

chemical reaction

Answer 24

process in which one compound or element is combined with others or is broken down; involves making/breaking of chemical bonds

Question 25

reactant

Answer 25

any of the starting materials in a chemical reaction

Question 26

functional group

Answer 26

small group of atoms bonded together in a precise configuration and exhibiting particular chemical properties that it imparts to any organic molecule in which it occurs

Question 27

solution

Answer 27

a liquid containing one or more dissolved solids or gases in a homogeneous mixture

Question 28

radioactive isotope

Answer 28

version of an element that has an unstable nucleus, which will release radiation energy as it decays to be more stable form. decay often results in the radioisotope becoming a different element

Question 29

chemical equilibrium

Answer 29

dynamic but stable state of a reversible chemical reaction

Question 30

acid

Answer 30

compound that gives up protons or accept electrons during a chemical reaction or that releases hydrogen ions when dissolved in H2O

Question 31

mass number

Answer 31

total number of protons and neutrons in an atom

Question 32

specific heat

Answer 32

the amount of energy required to raise the temperature of 1g of a substance by 1C

Question 33

valence electron

Answer 33

electron in the outermost shell of an atom

Question 34

first law of thermodynamics

Answer 34

the principle of physics that energy is conserved in any process. energy can be transferred and converted into different forms, but it cannot be created or destroyed.

Question 35

dalton (Da)

Answer 35

unit of mass equal to 1/12 the mass of one carbon-12 atom; about the mass of 1 proton or 1 neutron

Question 36

base

Answer 36

compound that acquires protons or gives up electrons during a chemical reaction or accepts hydrogen ions when dissolved in water

Question 37

ionic bond

Answer 37

chemical bond that is formed when an electron is completely transferred from one atom to another so that the atoms remain associated due to their opposite electric charges

Question 38

cohesion

Answer 38

tendency of certain like molecules to cling together due to attractive forces

Question 39

solute

Answer 39

any substance that is dissolved in a liquid

Question 40

hydroxide ion (OH-)

Answer 40

oxygen atom and a hydrogen atom joined by a single covalent bond and carrying a negative charge

Question 41

energy

Answer 41

capacity to do work or to supply heat

Question 42

photon

Answer 42

discrete packet of light energy; particle of light

Question 43

chemical energy

Answer 43

potential energy stored in covalent bonds between atoms

Question 44

product

Answer 44

any of the final materials formed in chemical reaction

Question 45

prebiotic soup model

Answer 45

hypothetical explanation for chemical evolution whereby small molecules reacted with one another in a mixture of organic molecules condensed into a body of water

Question 46

surface metabolism model

Answer 46

hypothetical explanation for chemical evolution whereby small molecules reacted with one another through catalytic activity associated with a surface.

Question 47

orbital

Answer 47

region of space around an atomic nucleus in which an electron is present most of the time

Question 48

system

Answer 48

defined set of interacting chemical components under observation

Question 49

molarity

Answer 49

common unit of solute concentration equal to the number of moles of a dissolved solute in 1 liter of solution

Question 50

molecular weight

Answer 50

sum of the atomic weights of all of the atoms in a molecule; roughly, total number of protons and neutrons in the molecule

Question 51

anion

Answer 51

negatively charged ION

Question 52

polar covalent bond

Answer 52

covalent bond which electrons are shared unequally between atoms differing in electronegativity, resulting in a partial negative and a partial positive charged atoms.

Question 53

element

Answer 53

substance, consisting of atoms with a specific number of protons. elements preserve their identity in chemical reactions

Question 54

structural formula

Answer 54

two dimensional notation in which chemical symbols for the constituent atoms are joined by straight lines single (--) double (=) or triple (=_ covalent bonds

Question 55

electronegativty

Answer 55

"grabbiness" of an atom. ability of an atom to attract electrons toward itself

Question 56

molecule

Answer 56

combination of two or more atoms held together by covalent bonds

Question 57

chemical bond

Answer 57

attractive force binding two atoms together. covalent, ionic, hydrogen bonds are examples of types of chemical bonds

Question 58

free radicals

Answer 58

substance containing one or more atoms with an unpaired electron. unstable and highly reactive

Question 59

homeostasis

Answer 59

array of relatively stable chemical and physical conditions in an anima's cells, tissue, and organs

Question 60

heat of vaporization

Answer 60

energy required to vaporize 1g of a liquid into a gas

Question 61

hydrophobic

Answer 61

"fear of water" not readily interacting with water. typically nonpolar compounds.

Question 62

mole

Answer 62

amount of substance that contains 6.022* 10^23 of its elemental entities

Question 63

chemical evolution

Answer 63

theory that simple chemical compounds in the early atmosphere and ocean combined via chemical reactions to form larger, more complex substances, eventually leading to the origin of life and the start of biological evolution.

Question 64

hydrogen ion (H+)

Answer 64

single proton with a charge of 1+; typically one that is dissolved in solution or that is being transferred from one atom to another in chemical react.

Question 65

endothermic

Answer 65

referring to a chemical react. that absorbs heat

Question 66

molecular formula

Answer 66

notation that indicated only the numbers and types of atoms in a molecule, such as H2O for the water molecule.