slide 2

Question 1

elements

Answer 1

There are 92 naturally occurring elements
which cannot be broken down by chemical
reactions into anything else.

Question 2

essential elements

Answer 2

20-25% of the 92 are essential elements, those

that organism needs to live and reproduce.

Question 3

The 4 elements that comprise 96% of living matter.

Answer 3

hydrogen, carbon, nitrogen and
oxygen
*

Question 4

Each element consists of one
kind of atom comprised of
sub-atomic particles:

Answer 4

nucleus:

• protons (positive charge)
• neutrons (no charge)

not:
- electrons (negative charge)

Question 5

An element’s atomic number

Answer 5

is the number of
protons in its nucleus.
*

Question 6

An element’s mass number

Answer 6

is the sum of protons
and neutrons in the nucleus and approximates the
atomic mass,
*

Question 7

atomic mass

Answer 7

the atom’s total mass

Question 8

Isotopes are

Answer 8

two atoms of an element that differ
in number of neutrons
*

Question 9

Radioactive isotopes

Answer 9

decay spontaneously,

giving off particles and energy

Question 10

Energy

Answer 10

is the capacity to cause change.

Question 11

Potential energy

Answer 11

is the energy that matter has
because of its location or structure.
*

Question 12

electron shell.

Answer 12

An electron’s state of potential energy is called

its energy level,

Question 13

(electron shells)

Answer 13

The electrons of an atom

occupy fixed energy levels

Question 14

The number of electrons

in the outer valence shell

Answer 14

influences the reactivity of

the atom.

Question 15

Atoms react to acquire

complete valence shells

Answer 15

Shell 1 – holds 2 electrons
Shell 2 – holds 8 electrons
Shell 3 – holds 8 electrons
*

Question 16

an ionic bond.

Answer 16

Transfer of electrons between atoms so that each
has a full outer shell forms an ionic bond
*

Question 17

covalent bond.

Answer 17

Sharing of electrons between atoms
forms a covalent bond. These bonds
are stronger than ionic bonds
*

Question 18

molecule.

Answer 18

Two or more atoms that form

covalent bonds

Question 19

Van der Waals interactions

Answer 19

occur when
transiently positive and negative regions of
molecules attract each other.
These are weak bonds, but are the forces that
allow geckos to climb walls!

Question 20

Water comprises

Answer 20

60 to 90% of most living organisms

Question 21

Water (H2O) is

Answer 21

a polar molecule

Question 22

Weak hydrogen bonds

Answer 22

among the
polar water molecules contribute to
important properties of water.

Question 23

Four of water’s properties that

facilitate life are:

Answer 23

– Cohesive behavior
– Ability to moderate
temperature
– Expansion upon freezing
– Versatility as a solvent
*

Question 24

cohesion.

Answer 24

Collectively, hydrogen bonds hold water molecules
together, a phenomenon called cohesion.
*

Question 25

Adhesion

Answer 25

is an attraction between different
substances, for example, between water and plant
cell walls.
*

Question 26

Adhesion

Answer 26

is an attraction between different
substances, for example, between water and plant
cell walls.

Question 27

Surface tension

Answer 27

is related to cohesion and is a measure of how hard it is to break the surface of a liquid.

Question 28

Temperature Moderation

Answer 28

Water absorbs heat from warmer air and releases
stored heat to cooler air.
Water can absorb or release a large amount of
heat with only a slight change in its own
temperature

Question 29

specific heat

Answer 29

of a substance is the amount of
heat that must be absorbed or lost for 1 g of that
substance to change its temperature by 1ºC

Question 30

The specific heat of water

Answer 30

is 1 cal/g/ºC

*

Question 31

– Heat is released when hydrogen bonds form

Answer 31

Heat is absorbed when hydrogen bonds break

*

Question 32

Water has a high heat of vaporization

Answer 32

which is
the heat a liquid must absorb for 1 g to be
converted to gas
*

Question 33

evaporative cooling

Answer 33

As a liquid evaporates, its remaining surface

cools, a process called evaporative cooling

Question 34

Water has its highest density at 4 C

Answer 34

and then
becomes less dense as it becomes a solid at
lower temperatures.
*

Question 35

Ice: Hydrogen bonds

are stable

Answer 35

Liquid water:
Hydrogen bonds
break and re-form

Question 36

The Solvent of Life

Answer 36

Water is a versatile solvent due to its polarity – can

form hydrogen bonds with other compounds

Question 37

When an ionic compound is

dissolved in water

Answer 37

each ion
is surrounded by a sphere
of water molecules

Question 38

Even large polar
molecules such as
proteins can
dissolve in water

Answer 38

if
they have ionic
and polar regions
*

Question 39

In aqueous solution most water molecules are

intact, but

Answer 39

some break apart or dissociate into ions,

molecules with a net positive or negative charge.

Question 40

The correct balance of
H+ and OHions
is
critical

Answer 40

for the proper
chemical functioning
of organisms

Question 41

The pH scale tells

Answer 41

how acidic or basic a solution is.

Question 42

pH 6 = 10-6 moles H+ per liter

Answer 42

(acid, more H+
)
*

Question 43

pH 7 = 10-7 moles H+ per liter

Answer 43

(neutral)

*

Question 44

pH 8 = 10-8 moles H+ per liter

Answer 44

(basic, less H+
)
*

Question 45

Acids donate H+ in

aqueous solutions

Answer 45

Bases donate OH-
or accept H+
in
aqueous solutions
*

Question 46

Ocean Acidification

Answer 46

CO2 dissolved in sea water forms carbonic acid;
this process is called ocean acidification.
*

Question 47

CO2
is the main product of burning fossil fuels.
About 25% of human-generated CO2
is absorbed
by the oceans.

Answer 47

Less carbonate ions are available for
marine organisms to use in the
formation of calcium carbonate

Question 48

Acid precipitation

Answer 48

is rain, fog, or snow with a pH
lower than 5.2
*

Question 49

Astrobiologists seeking life on other planets are

concentrating their search on planets with water.

Answer 49

More than 3000 planets have been found outside

our solar system; several of them contain water.