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1. CHEMISTRYCHEMISTRY

2. Composition of Matter
 Matter - Everything in
universe is composed of
matter
 Matter is anything that
occupies space or has
mass
 Mass – quantity of
matter an object has
 Weight – pull of
gravity on an object

3. ElementsElements
 Pure substances that cannot be broken
down chemically into simpler kinds of
matter
 More than 100 elements (92 naturally
occurring)

4.  90% of the mass of an
organism is composed of 4
elements (oxygen, carbon,
hydrogen and nitrogen)
 Each element unique
chemical symbol
 Consists of 1-2 letters
 First letter is always
capitalized

5. AtomsAtoms
 The simplest particle of
an element that retains
all the properties of that
element
 Properties of atoms
determine the structure
and properties of the
matter they compose
 Our understanding of the
structure of atoms based
on scientific models, not
observation

6. The NucleusThe Nucleus
 Central core
 Consists of positive
charged protons
and neutral
neutrons
 Positively charged
 Contains most of
the mass of the
atom

7. The ProtonsThe Protons
 All atoms of a given element have the
same number of protons
 Number of protons called the atomic
number
 Number of protons balanced by an equal
number of negatively charged electrons

8. The NeutronsThe Neutrons
 The number varies slightly among atoms
of the same element
 Different number of neutrons produces
isotopes of the same element

9. Atomic Mass
 Protons & neutrons are found in the
nucleus of an atom
 Protons and neutrons each have a
mass of 1 amu (atomic mass unit)
 The atomic mass of an atom is found
by adding the number of protons &
neutrons in an atom

10. The ElectronsThe Electrons
 Negatively charged high energy particles
with little or no mass
 Travel at very high speeds at various
distances (energy levels) from the
nucleus

11.  Electrons in the same energy level are
approximately the same distance from
the nucleus
 Outer energy levels have more energy
than inner levels
 Each level holds only a certain number of
electrons

12. Energy LevelsEnergy Levels
 Atoms have 7 energy levels
 The levels are K (closest to the
nucleus), L, M, N, O, P, Q
(furthest from the nucleus)
 The K level can only hold 2
electrons
 Levels L – Q can hold 8 electrons
(octet rule)

13. Periodic TablePeriodic Table
 Elements are arranged by their
atomic number on the Periodic Table
 The horizontal rows are called
Periods & tell the number of
energy levels
 Vertical groups are called Families &
tell the outermost number of
electrons

15. CompoundsCompounds
 Most
elements do
not exist by
themselves
 Readily
combine with
other
elements in
a
predictable
fashion

16.  A compound is a pure
substance made up of
atoms of two or more
elements
 The proportion of
atoms are always
fixed
 Chemical formula shows
the kind and proportion
of atoms of each
element that occurs in a
particular compound

17.  Molecules are the
simplest part of a
substance that
retains all of the
properties of the
substance and
exists in a free
state
 Some molecules are
large and complex

18. Chemical FormulasChemical Formulas
 Subscript after a symbol tell the
number of atoms of each element
 H20 has 2 atoms of hydrogen & 1
atom of oxygen
 Coefficients before a formula tell
the number of molecules
 3O2 represents 3 molecules of oxygen
or (3x2) or 6 atoms of oxygen

19.  The physical and
chemical
properties of a
compound differ
from the
physical and
chemical
properties of
the individual
elements that
compose it

20.  The tendency of
elements to combine and
form compounds depends
on the number and
arrangement of
electrons in their
outermost energy level
 Atoms are most stable
when their outer most
energy level is filled

21.  Most atoms are not stable in
their natural state
 Tend to react (combine) with
other atoms in order to
become more stable (undergo
chemical reactions)
 In chemical reactions bonds
are broken; atoms
rearranged and new chemical
bonds are formed that store
energy

22. Covalent Bonds
 Formed when two atoms share one or
more pairs of electrons

23. Ionic Bonds
 Some atoms become stable by losing or
gaining electrons
 Atoms that lose electrons are called
positive ions

24.  Atoms that gain electrons are called
negative ions
 Because positive and negative electrical
charges attract each other ionic bonds
form

25. Energy and MatterEnergy and Matter
 Energy
 The ability to do work or cause
change
 Occurs in various forms
 Can be converted to another form
 Forms important to biological
systems are chemical, thermal,
electrical and mechanical energy
 Free energy is the energy in a
system that is available for work

26. States of MatterStates of Matter
 Atoms are in constant motion
 The rate at which atoms or molecules in
a substance move determines its state

27.  Solid
 Molecules tightly linked together in
a definite shape
 Vibrate in place
 Fixed volume and shape

28.  Liquids
 Molecules not as tightly linked
as a solid
 Maintain fixed volume
 Able to flow and conform to
shape of container

29. Gas
Molecules have little
or no attraction to each
other
Fill the volume of the
occupied container
Move most rapidly
 To cause a substance to
change state, thermal energy
(heat) must be added to or
removed from a substance

30. Energy and Chemical Reactions
 Living things
undergo
thousands of
chemical
reactions as part
of the life
process

31.  Many are very complex
involving multistep sequences
called biochemical pathways
 Chemical equations represent
chemical reactions
 Reactants are shown on the
left side of the equation
 Products are shown on the
right side

32.  The number of
each kind of atom
must be the same
on either side of
the arrow (equation
must be balanced)
 Bonds may be
broken or made
forming new
compounds

33. Energy TransferEnergy Transfer
 Much of the energy
organisms need is
provided by sugar (food)
 Undergoes a series of
chemical reactions in
which energy is released
(cell respiration)
 The net release of free
energy is called an
exergonic (exothermic)
reaction

34.  Reactions that involve a
net absorption of free
energy are called
endergonic (endothermic)
reactions
 Photosynthesis is an
example
 Most reactions in living
organisms are endergonic;
therefore living organisms
require a constant source
of energy

35.  Most chemical reactions require energy
to begin
 The amount of energy needed to start
the reaction is called activation energy

36.  Certain chemical
substances
(catalysts)
reduce the
amount of
activation energy
required
 Biological
catalysts are
called enzymes

37.  Enzymes are an important class of
catalysts in living organisms
 Mostly protein
 Thousands of different kinds
 Each specific for a different chemical
reaction

38. Enzyme Structure
 Enzymes work on
substances called
substrates
 Substrates must fit into
a place on an enzyme
called the active site
 Enzymes are reusable!

39. Reduction-Oxidation Reactions
 Many of the chemical reactions that
help transfer energy in living organisms
involve the transfer of electrons
(reduction-oxidation = redox reactions)

40.  Oxidation reaction – reactant loses
electron(s) becoming more positive

41.  Reduction reaction – reactant gains
electron(s) becoming more negative

42. Solutions

43. SolutionsSolutions
 A solution is a
mixture in
which 2 or
more
substances are
uniformly
distributed in
another
substance

44.  Solute is the
substance dissolved
in the solution
 Particles may be
ions, atoms, or
molecules
 Solvent is the
substance in which
the solute is
dissolved
 Water is the
universal solvent

45.  Solutions can be composed of
varying proportions of a given
solute in a given solvent ---
vary in concentration
(measurement of the amount of
solute)
 A saturated solution is one in
which no more solute can be
dissolved
 Aqueous solution (water) are
universally important to living
things

46.  Dissociation of water
 Breaking apart of the water
molecule into two ions of
opposite charge (due to
strong attraction of oxygen
atom of one molecule for H
atom of another water
molecule)
 H2O  H+
(hydrogen ion) +
OH-
(hydroxide ion)
 H+
+ H2O  H3O
(hydronium ion)

47. Acids and BasesAcids and Bases
 One of the most important aspects of a
living system is the degree of acidity or
alkalinity

48. AcidsAcids
 Number of hydronium ions in solutions is
greater than the number of hydroxide
ions
 HCl  H+
+ Cl-

49. BasesBases
 Number of hydroxide ions in solution is
greater than the number of hydronium
ions
 NaOH  Na+
+ OH-

50. pH ScalepH Scale
 logarithmic
scale for
comparing the
relative
concentrations
of hydronium
ions and
hydroxide ions
in a solution
 ranges from 0
to 14
 Each pH is 10X
stronger than next
 e.g. ph 1 is 10 times
stronger than ph 2

51.  the lower the pH the stronger the acid
 the higher the pH the stronger the base
 pH 7.0 is neutral

52. BuffersBuffers
 Control of pH is very
important
 Most enzymes function
only within a very
narrow pH
 Control is accomplished
with buffers made by
the body
 Buffers keep a neutral
pH (pH 7)

53.  Buffers neutralize
small amounts of either
an acid or base added
to a solution
 Complex buffering
systems maintain the
pH values of your
body’s many fluids at
normal and safe levels