Unit One: The Chemistry of Life
chemistry- study of the composition of matter
and the changes that matter undergoes
matter- anything that has mass and takes up
space (volume)
-matter is all around you
volume- amount of space an object occupies
mass- quantity of matter in an object
Phases/States of Matter
-solids
-liquids
-gases
-matter can undergo changes
physical change- alters a given material without
changing its composition
-described by words like cutting, grinding, bending
-are reversible
ex- carving wood, melting ice, stretching rubber
band
chemical change- results in a change in
chemical composition of a substance
-change is not reversible
-described by words like burn, rot, rust, explode
ex- wood burning, iron left out in the rain
element- pure substance, one type of atom
Ex: hydrogen, carbon, oxygen, sodium
-all found on the periodic table
-represented by chemical symbols; H, C, O, Na
atom – basic unit of all matter
-extremely small
-comes from Greek word atomos- unable to cut
-made up of three subatomic particles:
protons, neutrons, and electrons
**protons and neutrons have the same mass
-both found in the nucleus- center of the atom
protons (p+) have a + charge
neutrons (n0) have no charge, neutral
-electrons are much smaller
-found orbiting the nucleus in energy levels or
electron clouds and are attracted to p+
electrons (e-) carry a - charge
** # of p+ = # of e- in an atom making it
electrically neutral
*REMEMBER*
# of p+ = # of e- in an atom
atomic number- number of protons in the
nucleus of an atom
(smaller number on the periodic table)
-also = # of electrons b/c of above *
-specific to each element
mass number- total number of protons and
neutrons in an atom
-larger number on periodic table
-must be rounded to a whole number
# of n0 = mass # - atomic #
-element can be written as He-4
*atomic # never changes, but mass # can
Ex: How many p+, e- and n0 in each?
1) calcium
p+ = 20
e- = 20
n0 = 20
2) chlorine
p+ = 17
e- = 17
3) p+ = 28 e- = 28
nickel
n0 = 18
n0 = 31
isotope- atoms of the same element having the
same # of p+ and e-, but different # of n0
exNe-20
10p+ 10e- 10n0
Ne-21
10p+ 10e- 11n0
Ne-22
10p+ 10e- 12n0
Isotopes of carbon
6 electrons
6 protons
6 neutrons
6 electrons
6 protons
7 neutrons
6 electrons
6 protons
8 neutrons
radioactive isotopes- have unstable nuclei that
break down over time
-radiation can be dangerous
-can also be helpful to:
*determine age of rocks
*treat cancer
*kill bacteria that cause food to spoil
*trace substances through organisms
chemical compounds- formed by the chemical
composition of two or more elements in
definite proportions
-represented by:
chemical formula- shows the kinds and number
of each element in a compound
ex- H2O
CO2
H3PO4
chemical bonds- what holds compounds
together
*valence electrons (e- in outermost energy level)
are involved in bonding
-bonds can be ionic or molecular/covalent
ionic bonds- transfer of e- from one ion (atom
with a charge) to another
-form ionic compounds (metal + non-metal)
-metal = + charged (cation)
*loses e-non-metal = - charged (anion)
*gains e-
Ionic Bonding
CaCℓ2
calcium chloride
calcium = positive ion
chlorine = negative ion
covalent bonds
-electrons are shared between atoms
*bonds (pair of e-) are represented as dashes (─)
single covalent bond- two atoms share a pair of
e- (─)
double covalent bond- bond that involves two
shared pairs of e- (═)
triple covalent bond- bond that involves three
shared pairs of e- (≡)
*covalent bonds form molecules (2 or more
nonmetals)
methane
CH4
Van der Waals forces- intermolecular force
between molecules
*not a bond so weaker than ionic and covalent
bonds
ex: geckos on walls
Think about this:
In order for life to exist anywhere in the universe
what must be present?
WATER
1. Working with a partner, make a list of ten
things that have water in them.
2. Exchange your list for the list of another pair
of students. Did your lists contain some of the
same things? Did anything on the other list
surprise you?
3. Did either list contain any living things?
WATER
-makes up about 60% of human body
-covers ¾ of the Earth’s surface
-exists as a solid, liquid or gas in nature
-solid water floats in liquid water because it is
less dense
*water = H2O
Does H2O form a covalent or ionic bond?
COVALENT
*sharing of e-
*Water is polar
-bonding e- shared unequally between H and O
-because oxygen has more p+ than H, it is
likely that the shared e- are closer to the O
-oxygen has negative end and H has positive
end
Hydrogen Bonding
-not as strong as ionic or covalent bonds
-more like a force between molecules than a
bond
*+ end attracted to – end
-many of water’s properties are due to hydrogen
bonding
cohesion- attraction between molecules of the
same substance
-creates surface tension
Page 41 Fig 2-8
adhesion- attraction between molecules of
different substances
ex: capillary action
-water is not always pure
mixture- 2 or more substances physically and
not chemically combined
Types of mixtures with water
1. solution- uniform in composition
ex: salt water
solute- what is dissolved
ex: salt
solvent- what does the dissolving
ex: water
2. suspension- water and nondissolved material
ex: muddy water, blood with cells
Acids and Bases
acid- any compound that produces H+ in
solution
exHCℓ → H+ + Cℓ-
base- any compound that produces OH- in
solution (low H+)
exNaOH → Na+ + OH-
*pH scale is used to measure H+
pH = potential hydrogen
-pH scale ranges from 0-14
-pH < 7 = acids
*more H+
-pH > 7 = bases
*more OH-pH = 7 = neutral solution
**based on scales of 10
page 43 fig 2-10
buffers- weak acids or bases that resist pH
changes
*aid in keeping pH regulated in cells
Carbon Compounds
organic chemistry- the study of compounds that
contain bonds between carbon (C) atoms
*C has four valence e- (e- in outermost energy
level)
*can form four covalent bonds
*can have single, double or triple bonds
*C bonds with H, O, N, P and S
*C can form long chains and complex molecules
Carbon Compounds
Macromolecules
-giant molecules
-made of many smaller molecules
-formed by polymerization- large molecules are
formed by joining smaller ones together
monomers- smaller units
polymers- larger units formed
*like a puzzle
-monomers are joined together by dehydration
synthesis
-removes a water molecule to form a
polymer
Hydrolysis- water is added to separate a
polymer into its monomers
Groups of organic compounds in living things:
1. carbohydrates
2. lipids
3. nucleic acids
4. proteins
Carbohydrates
*made up of C, H and O
*in a 1:2:1 ratio
ex- C6H12O6
*main source of energy
ex- sugars and starches (long chain of sugars)
*can be stored as complex sugars
monomers = monosaccharide- single sugar
molecules
ex- glucose, galactose and fructose
polymers = polysaccharides- larger molecule
formed from many monosaccharides
ex- glycogen (excess stored sugar) and cellulose
(found in wood)
Lipids
*made up of C and H and some O
*not soluble in water (do not dissolve)
*store energy and form membranes
monomers = glycerol and fatty acids
polymer = fats, oils and waxes
page 46 fig 2-14: LIPIDS
Saturated vs Unsaturated Fatty Acids
saturated- all single bonds which leads to
maximum # of H
unsaturated- at least one double bond between
two carbon atoms
-not loaded with H
Nucleic acids
*macromolecules containing H, O, N,C and P
*store and transmit hereditary or genetic info
monomers = nucleotides
-consists of 5-C sugar, a phosphate group
and a nitrogenous base
polymer = nucleic acid (DNA/RNA)
Proteins
*contain C, N, H and O
*have an amino group and a carboxyl group
*most diverse macromolecule b/c of R-groups
*regulates cell processes, control reaction rates,
transport substances and fight disease
monomers = amino acids
polymer = protein
Amino Acids and Proteins
general structure
alanine
serine
Chemical Reactions and Enzymes
chemical reaction- process that changes one set
of chemicals into another
-atoms are rearranged
-some reactions are fast
ex: something blowing up
-some are slow
ex: rust forming
ex:
CO2 + H2O  H2CO3
reactants- elements or compounds that enter a
reaction
(in ex. CO2 and H2O)
products- elements or compounds formed during
reaction
(in ex. H2CO3)
-chemical reactions involve the breaking and
making of bonds
-the number of each element you begin with
must be the same as you end with
ex:
C
O
H
CO2 + H2O  H2CO3
reactants
products
1
1
3
3
2
2
-energy is either released or absorbed when
bonds are made or broken
ex: we release energy when we metabolize
our food
activation energy- energy needed to get a
reaction started
-if the activation energy cannot be reached there
will not be a reaction
activation energy
products
reactants
reactants
activation energy
products
catalysts- substances that speed up the rate of a
chemical reaction
-lowers activation energy
enzymes- proteins that speed up reactions in
cells
*biological catalysts
reaction pathway without enzyme
activation energy without enzyme
reactants
reaction pathway with enzyme
activation
energy with
enzyme
products
substrates- reactants of enzyme-catalyzed
reactions
-substrates bind with enzymes
-enzymes are specific- can only bond with one
type of substrate
-like a lock and key
Enzymes jobs include:
1. regulating chemical pathways
2. making materials that cells need
3. releasing energy
4. transferring info
enzyme
glucose
ADP
products
substrates
ATP
glucose-6phosphate
products are
released
active site
enzyme-substrate
complex
substrates are
converted into
products
substrates
bind to
enzyme