Elements of Life Slideshow text
Atoms - Smallest stable unit of matter that has the characteristics of its specific element
Atoms Structure: Nucleus with electron orbitals.
Protons are positively charged. Neutrons are neutral and have no charge.
Electrons and orbitals
Electrons are negatively charged. Each orbital has a different amount of energy associated with it.
Closer to the nucleus = lower energy level orbital
Farther away = higher energy level
orbital
Atoms
Valence Electron
Atoms
Or…. What is the smallest unit of matter that biochemists care about for 800, Alex?
★ Valence electrons
○ Found in the
outermost orbital
★ Used for making different
types of bonds!
★ Most elements want 8
electrons in their valence
shell because this makes them
the most stable.
Have a positive
(+ )Charge
Cations
Have more
electrons than
protons
★Atoms are usually neutral
○ # electrons = # of protons
Ionsatoms are
★Non-neutral
called ions. Two Types.
Have more protons
than electrons
Anions
Have a negative (-)
charge
Elements of Life
Main Elements of life:
Carbon, Hydrogen, Oxygen, Nitrogen (CHON)
★ All the others are trace elements
○ Found in small (trace)
amounts in the body
○ BUT they are critical to
maintaining homeostasis.
○ Without them organisms
would quickly die.
• C.H.N.O.P.S
The Importance of carbon
Or…. Why Carbon is the basis of organic life forms
★ Inorganic carbon is fixed from the
atmosphere by plants during
photosynthesis
○ Incorporated into carbohydrates
○ Main source of biomass in
ecosystems
★ Organisms utilize carbon to produce
every biomolecule (carbohydrates,
proteins, nucleic acids, lipids)
★ When organisms die, decomposers
recycle the carbon back into the
environment.
★ Organisms is carbon-depleted areas
will die because they cannot make the
necessary biological molecules.
The Importance of Nitrogen
Or…. why nitrogen is important FOR THE GAINS
★ Inorganic nitrogen is fixed from the
atmosphere by bacteria and other
decomposers and absorbed by
plants to enter the food web.
★ Organisms utilize nitrogen to
produce proteins and nucleic acids.
★ Nitrogen is recycled into the
environment by decomposers.
★ Organisms in nitrogen depleted
areas will die because they cannot
make proteins or nucleic acids.
The Importance of Phosphorus
Or…. why life as we know it would not exist without phosphorus
★ Phosphorus is used to build nucleic
acids and certain types of lipids
(phospholipids) .
★ Organisms in phosphorus depleted
areas will die because they cannot
make nucleic acids or phospholipids
(the major component of cell
membranes).
★ Electronegativity is the
measurement of how strongly
atoms attract bonding electrons to
themselves.
○ i.e. It’s the measurement of how
much they will pull electrons
toward themselves.
★ Determined by how many electrons
are in the valence shell.
★ The closer to eight electrons they
have, the more electronegative the
Or…. probably the single most important chemistry concept to
element is.
understand if you want to be able to understand anything in this
Electronegativity
unit, biochemistry, organic chemistry (basically any chemistry)
Electronegative Elements you need to know
FON
Fluorine
Oxygen
Nitrogen
Most electronegative
element!!!
More electronegative
than nitrogen
Least electronegative
of the three.
Not common in
Biology, but I expect
you to know it
anyway.
Less electronegative
than fluorine, more
electronegative than
nitrogen.
Still
a
very
electronegative
element though
Electropositivity
A measurement of the ability of elements to donate electrons
and form positive ions.
★ These elements usually have 1 or
2 electrons in their valence shells.
★ They are NOT very
electronegative.
Electrons and
Bonding
Occur
when
two
atoms share electrons
Covalent Bonds
Ionic bonds are weaker
than covalent bonds and
will dissociate in water,
so we don’t see them alot
in biology.
Covalent Bonds vs.
Ionic Bonds
Energy is stored in
covalent bonds and
is released when the
bond is broken
Ionic Bonds
Transfer of valence
electrons from a metal
to a non-metal
Polarity
AKA a direct consequence of electronegativity that is super
important to how life as we know it operates.
★ Polar molecules occur when
there is unequal sharing of
electrons across a covalent
bond.
★ Happens when a very
electronegative element is
bonded to a very small OR
very electropositive element.
Polarity
AKA a direct consequence of electronegativity that is super
important to how life as we know it operates.
★ Polar molecules have an
OVERALL NEUTRAL CHARGE
★ BUT they have partial negative
and partial positive charges on
the poles.
★ Electronegative element will be
partially negative because it is
pulling electrons toward itself.
★ Electropositive element will be
partially positive because it has
less electron density near itself.
Hydrogen bonds
Weak attraction between a hydrogen bonded to an oxygen (O),
Nitrogen (N) or Fluorine (F) and another O, N or F atom.
★ Why only O, N and F?
○ They are very electronegative.
○ Hydrogens bonded to them have a
partial positive charge.
○ O,N and F in other areas have a
partial negative charge.
★ Opposite charges attract!
★ This forms the hydrogen “bond”
Bonds and Molecular Shape
★ How atoms are bonded together
determines their overall shape.
★ The structure, shape and
chemical properties of a
molecule determines the
function of that molecule.
○ This is super important and will
show up over and over again for
the rest of forever.
Laws of Conservation
★ Energy is ALWAYS conserved in a reaction.
○ Energy that appears “lost” was probably given off as heat.
★ The amount and types of atoms are conserved in a reaction.
○ If you start with two oxygens and four hydrogens, you must end with the same (unless
more are added in)
★ The amount of bonds in a chemical reaction are conserved.
○ If you start with four bonds, you end with four bonds.
Any Questions?