2: Chemical Basis of Life

Question 1

Isotopes

Answer 1

atoms of same element that differ in # of neutrons.

(Same # of protons but different mass #’s)

Question 2

Octet rule

Answer 2

atom has 2 or more shells, outer shell is most stable with 8 electrons

(no reactions)

Question 3

Valence Shell

Answer 3

of electrons in atom’s outer shell

Question 4

Molecule

Answer 4

group of atoms bonded together

Question 5

Compound

Answer 5

when molecule has atoms of more than 1 element

Question 6

Ionic Bond

Answer 6

when 2 atoms held together by attraction btwn opposite charges

Question 7

Ions

Answer 7

charged atoms due to electron transfer

Question 8

Covalent Bond

Answer 8

when 2 atoms share electrons to have completed outer shell

Question 9

Reactant

Answer 9

molecules that participate in reaction

Question 10

Product

Answer 10

molecule formed by reaction

Question 11

electronegativity

Answer 11

atom’s attraction to electrons in covalent bond

Question 12

Hydrophilic Molecules

Answer 12

attracted to water

Question 13

Hydrophobic Molecules

Answer 13

nonionized & nonpolar which are not atracted to water

Question 14

H2O cohesion/adhesion

Answer 14

• water molecules cling together from hydrogen bonding
• flows freely
• adheres to other polar surfaces b/c pos and neg poles
• makes transpo easy

Question 15

Acids

Answer 15

substances that dissociate in water, releasing hydrogen ions

Question 16

Bases

Answer 16

substance that either take up hydrogen ions or release hydrogen ions

Question 17

pH

Answer 17

indicates # of hydrogen ions in a solution

Question 18

pH scale

Answer 18

• indicates acidity or basicity of a solution
• from 0-14
• 7=neutral, below 7=acidic, above 7=basic

Question 19

Buffer

Answer 19

chemical or combo of chemicals that keep pH in normal limits