Biology Midterm: chp 4

Question 1

trace elements

Answer 1

make-up 0.01% of the human body

Question 2

element

Answer 2

a pure substance that can’t be broken down into other substances by chemical means

Question 3

compound

Answer 3

a substance containing two or more elements that are chemically combined in a fixed ration (can be chemically broken down)

Question 4

atom

Answer 4

smallest possible particle of an element
proton(+, in nucleus)
neutron(neutral, in nucleus)
electron(-, in shells)

Question 5

isotope

Answer 5

an element wit the same number of protons but different number of neutrons

Question 6

radioactive isotopes

Answer 6

useful for researchers because they are used as “biological spies” for observing what happens to different atoms within organisms

Question 7

role of an elements electrons in determine chemical reactivity

Answer 7

elements electrons determine its chemical reactivity because depending on the number of electrons on the outer shell it can react and form either covalent or ionic bonds with other elements who have the number of electrons they don’t have in their outer shell

Question 8

ionic bond

Answer 8

forms when an atom transfers an electron to another atom

Question 9

covalent bond

Answer 9

forms when an electron is shared between two atoms

Question 10

structure of a water molecule

Answer 10

two positive hydrogen and one negative oxygen

polar molecule

Question 11

waters unique properties

Answer 11

cohesion
adhesion
temperature moderation
low density of ice
ability to dissolve other substances

Question 12

cohesion

Answer 12

tendency of molecules of the same kind to stick to one another

Question 13

adhesion

Answer 13

type of attraction that occurs between unlike molecules

Question 14

temperature moderation

Answer 14

water has a better ability to resist temperature change

Question 15

low density of ice

Answer 15

solid is less dense that liquid form

Question 16

ability to dissolve other substances

Answer 16

can dissolve things; is a solvent

Question 17

acid

Answer 17

1-7 on pH scale

compound that donates H+ ions to a solution

Question 18

base

Answer 18

7-14 on pH scale

compound that removed H+ ions from an aqueous solution

Question 19

atomic number

Answer 19

same number of protons

Question 20

ion

Answer 20

when an atom has an electric charge

Question 21

buffers

Answer 21

resist changes in pH

Question 22

most common elements

Answer 22

oxygen (O)
carbon (C)
hydrogen (H)
nitrogen (N)