Chapter 2: The Chemical Basis of Life

Question 1

atoms

Answer 1

the smallest functional units of matter that form all chemical substances

Question 2

protons

Answer 2

positive charge, found in nucleus

Question 3

neutrons

Answer 3

neutral charge, found in nucleus

Question 4

electrons

Answer 4

negative charge, found in orbitals

Question 5

alpha particles

Answer 5

made up of 2 protons and 2 neutrons from the nucleus of He

Question 6

Rutherford Gold Foil Experiment Results

Answer 6

1. 98% of alpha particles continued undeflected&raquo_space; atoms are made up of mostly empty space
2. <2% of alpha particles were slightly deflected&raquo_space; the nucleus is positively charged
3. 0.01% of alpha particles bounced back&raquo_space; the nucleus is dense

Question 7

orbitals

Answer 7

places where the probability of finding an electron is high

Question 8

shells

Answer 8

contain a group of orbitals, outside part of an atom around the nucleus

Question 9

stable atom

Answer 9

all electron orbitals are full

Question 10

Hund’s Rule

Answer 10

electrons fill orbitals one at a time and from the lowest energy level to the highest

Question 11

valence electrons

Answer 11

outermost electrons, available to combine with other atoms

Question 12

atomic number

Answer 12

number of protons

Question 13

Periodic Table

Answer 13

organized by atomic number with one or two letter symbols for each element

Question 14

rows in the Periodic Table indicate

Answer 14

the number of electron shells

Question 15

columns in the Periodic Table indicate

Answer 15

the number of electrons in the outer shell (valence electrons)

Question 16

atomic mass

Answer 16

protons + neutrons

Question 17

weight

Answer 17

derived from the gravitational pull on a given mass

Question 18

mole

Answer 18

one mole of any element contains 6.022 * 10^23 atoms

Question 19

Avogadro’s Number

Answer 19

6.022 * 10^23

Question 20

isotopes

Answer 20

many elements exist in multiple forms that differ in the number of neutrons

Question 21

radioisotopes

Answer 21

unstable isotopes that decay in half-lives

Question 22

half-life

Answer 22

the time it takes for half of a radioisotope to decay

Question 23

elements that make up living things

Answer 23

hydrogen, oxygen, carbon, and nitrogen

Question 24

trace elements

Answer 24

elements found <0.01% in the body but are essential for normal function

Question 25

molecule

Answer 25

two or more atoms bonded together

Question 26

compound

Answer 26

any molecule composed of 2 or more elements

Question 27

bonds

Answer 27

atoms in molecules are held together by chemical bonds

Question 28

covalent bond

Answer 28

electrons are shared to fill valence shells

Question 29

hydrogen 'bond'

Answer 29

hydrogen atom from one polar molecule is attracted to an electronegative atom from another molecule - individually weak, many are strong - reversible

Question 30

ionic bond

Answer 30

electrons are transferred, forming ions that are attracted to each other

Question 31

anions

Answer 31

ions with a net negative charge

Question 32

cations

Answer 32

ions with a net positive charge

Question 33

Octet Rule

Answer 33

atoms are stable when their outer shell is full

Question 34

electronegativity

Answer 34

ability to attract electrons

Question 35

polar covalent bonds

Answer 35

when 2 atoms with different electronegativities form a covalent bond, the shared electrons are closer to the more electronegative atom

Question 36

polarity

Answer 36

unequal distribution of electrons creates a difference in electric charge across the molecule

Question 37

nonpolar covalent bonds

Answer 37

between atoms with similar electronegativities with equal sharing of electrons

Question 38

shape of a molecule:

Answer 38

determined by the arrangement and number of bonds between atoms

Question 39

free radicals

Answer 39

a molecule with a free, unpaired electron in its outer shell | - highly reactive and can harm cells

Question 40

chemical reactions

Answer 40

when one or more substances are changed into other substances

Question 41

Properties of Chemical Reactions

Answer 41

1. require a source of energy 2. require enzymes as a catalyst in living organisms 3. tend to proceed in a particular direction 4. occur in liquid

Question 42

solution

Answer 42

solutes in a solvent

Question 43

solutes

Answer 43

dissolved substances

Question 44

solvent

Answer 44

liquid

Question 45

aqueous solutions

Answer 45

solutions made with water

Question 46

hydrophillic

Answer 46

readily dissolves in water

Question 47

hydrophobic

Answer 47

do not dissolve in water

Question 48

amphipathic

Answer 48

have both polar/ionized and nonpolar regions | - may form micelles in water

Question 49

bile salts

Answer 49

contain polar and nonpolar parts to digest lipids | - produced by liver and stored in the gallbladder

Question 50

emulsification

Answer 50

breaking of large globules into smaller ones

Question 51

emulsion

Answer 51

multiple tiny lipid droplets each coated with bile salts

Question 52

concentration

Answer 52

amount of a solute dissolved in a unit volume of solution

Question 53

molarity

Answer 53

umber of moles of solute dissolved in 1 L of water

Question 54

molecular mass

Answer 54

sum of the atomic masses of all the atoms in a molecule

Question 55

vaporization

Answer 55

change from liquid to gas, energy needed

Question 56

heat of vaporization

Answer 56

energy needed to bring 1 mol of a substance to its boiling point

Question 57

freezing

Answer 57

change from liquid to solid (ice), energy is released

Question 58

heat of fusion

Answer 58

energy needed or released to bring a substance from liquid to solid

Question 59

specific heat

Answer 59

the amount of heat energy required to raise one unit of mass of a substance by 1 degree C

Question 60

Properties of Water

Answer 60

- temperature at which water freezes is influenced by the amount of dissolved solutes - water is incompressible - cohesion and adhesion

Question 61

cohesion

Answer 61

water molecules attract each other

Question 62

adhesion

Answer 62

water adheres to surfaces (ex: digestive tract)