ch 2 & 3

Question 1

Common elements in living organisms

Answer 1

Oxygen, hydrogen, carbon, nitrogen

Question 2

atomic models

Answer 2

atomic nucleus: protons (+), nuetrons (no charge)
Eelctrons (-): orbit atomic nucleus

Question 3

Chemical bonds

Answer 3

hold atoms together; gain, loss, sharing of electrons

Question 4

ionic bond

Answer 4

gain or loss of electrons

Question 5

covalent bond

Answer 5

sharing electrons

Question 6

hydrogen bond

Answer 6

between polar molecules

Question 7

chemical reactions

Answer 7

making and breaking of chemical bonds

Question 8

weak bonds

Answer 8

ionic bonds, hydrogen bonds, hydrophobic interactions

Question 9

strong bonds

Answer 9

covalent bonds

Question 10

polar

Answer 10

electrons are shared unequally

Question 11

nonpolar

Answer 11

electrons are shared equally

Question 12

ions

Answer 12

formed when molecules lose or gain electrons

Question 13

hydrogen bond

Answer 13

bond between parts of polar molecules

Question 14

Cohesion

Answer 14

water molecules stick together

Question 15

surface tension

Answer 15

surface of water is resistant to being broken

Question 16

adhesion

Answer 16

water sticks to polar surface

Question 17

pH scale

Answer 17

express degree of acidity of a solution; scale 0-14

Question 18

acid

Answer 18

<ph7

Question 19

base

Answer 19

> pH7

Question 20

neutral

Answer 20

pH=7 (equal amount of H^+ and OH^-)

Question 21

elements

Answer 21

elements are fundamental substances that consist of only one kind of atom; each of us is a collection of elements

Question 22

atomic number

Answer 22

number of protons; number of electrons

Question 23

mass number

Answer 23

number of protons + number of nuetrons

Question 24

isotope

Answer 24

form of an element that varies in its atomic weight (varying number of neutrons)

Question 25

radioactive

Answer 25

isotopes are unstable and spontaneously split into smaller parts

Question 26

hydrophilic (water loving) molecules

Answer 26

attraction to water (ions and polar molecules)

Question 27

hydrophobic (water fearing) molecules

Answer 27

no attrqaction to water (do not dissolve; fats and oils)

Question 28

adhesion

Answer 28

water sticks to polar surface

Question 29

buffer

Answer 29

helps maintain a solution at a relatively constant pH

Question 30

acids

Answer 30

chemicals that release hydrogen atoms (H^+) when dissolved in water

Question 31

bases (alkaline compounds)

Answer 31

compounds that release negatively charged hydroxyl ions when dissolved in water

Question 32

valence electrons

Answer 32

the electrons in an atom's outermost energy shell that are available to participate in chemical bonds and reactions

Question 33

electronegativity

Answer 33

the measure of an atom's ability to attract and hold electrons in a chemical bond

Question 34

cation

Answer 34

a positively charged ion

Question 35

anion

Answer 35

negatively charged ion

Question 36

chemical equilibrium

Answer 36

the state in a reversible reaction where the rates of the forward (reactants to products) and reverse (products to reactants) reactions are equal, resulting in no net change in the concentrations of reactants and products over time

Question 37

acid precipitation

Answer 37

rain, snow, fog, hail, or even dry dust that is acidic due to atmospheric pollutants, primarily sulfur dioxide and nitrogen oxides from the burning of the fossil fuels

Question 38

ocean acidification

Answer 38

the ongoing decrease in the ocean's pH caused by the absorption of excessive carbon dioxide (CO2) from the atmosphere primarily from human activities like burning fossil fuels

Question 39

colloid

Answer 39

any substance consisting of particles substantially larger than atoms or ordinary molecules but too small to be visible to the unaided eye

Question 40

specific heat

Answer 40

the amount of heat energy needed to raise the temperature of one gram of a substance by one degree Celsius

Question 41

joule

Answer 41

a standard unit used to measure energy or work

Question 42

calorie

Answer 42

measurement of energy

Question 43

solution

Answer 43

a homogeneous mixture where one or more substances (solutes) are completely dissolved in another substance (solvent) typically water

Question 44

solutes

Answer 44

a substance (solid, liquid, gas) that dissolves in a solvent to form a solution

Question 45

solvent

Answer 45

a liquid that dissolves solutes (like nutrients, gases, and waste products) to form solutions