Chemistry of Life

Question 1

element

Answer 1

a pure substance that cannot be broken down (periodic table of elements); 92 occur naturally ; 4 are essential to life

Question 2

atom

Answer 2

the building block of matter

Question 3

nucleus

Answer 3

center of an atom; it has protons and neutrons

Question 4

isotope

Answer 4

atoms of the same element with a different number of neutrons; often used in medicine (radioactive) and carbon dating

Question 5

compound

Answer 5

a substance made of two or more elements bonded together in fixed proportions (H + 0&raquo_space; water; sodium + chlorine&raquo_space;salt)

Question 6

covalent bond

Answer 6

when atoms share one or more pairs of electrons

Question 7

molecule

Answer 7

two or more atoms held together by covalent bonds

Question 8

ion

Answer 8

an atom that has gained or lost one or more electrons
(# protons no longer equals # electrons)
cation = positive charge (lost electrons)
anion = negative charge (gained electrons)

Question 9

ionic bond

Answer 9

atoms exchange electrons

Question 10

pH

Answer 10

the measure of hydrogen ions in a solution

Question 11

acid

Answer 11

high # of hydrogen ions (low number on pH scale)

Question 12

base

Answer 12

low # of hydrogen ions (high number on pH scale and high # of hydroxide)

Question 13

polarity

Answer 13

having two opposite poles

Question 14

atomic number

Answer 14

number of protons

Question 15

atomic MASS

Answer 15

n + p

Question 16

to find the number of neutrons

Answer 16

atomic mass - protons = neutrons

Question 17

buffer

Answer 17

resists change in pH

Question 18

hydrogen bond

Answer 18

attractive force between H and another atom - allows for water to have special qualities

Question 19

cohesion

Answer 19

molecules of same substance “stick” together (penny demo)

Question 20

adhesion

Answer 20

molecules of different substances “stick” together

Question 21

surface tension

Answer 21

cohesion on a large scale creates a “surface” (ex. water bug)

Question 22

universal solvent

Answer 22

water breaks up many substances (because of the polar ends of the H bonds)

Question 23

high heat of vaporization

Answer 23

when water goes from liquid to gas, it takes a lot of energy

Question 24

less dense as a solid

Answer 24

ice floats (air gets trapped in the open spaces of the molecule as water freezes)

Question 25

high specific heat

Answer 25

it takes a great amount of energy to heat water