Post on 19-Dec-2015
Biochemistry
Chemistry of Life
General Chemistry
Elements: Substances that cannot be broken
down chemically into simpler substances.
Periodic Table of Elements
General Chemistry
Atoms: A particle that makes up an element. Still contains the same chemical
properties of that element.
Atomic Structure
6 electrons6 protons6 neutrons
Carbon 12
Electrons are part of whatmakes an atom an atom
Electrons are part of whatmakes an atom an atom
atom
But where exactly are theelectrons inside an atom?
Orbitalsare areas within atoms
where there is a high probablilityof finding electrons.
Knowing how electrons arearranged in an atom is
importantbecause that governshow atoms interact
with each other
Knowing how electrons arearranged in an atom is
importantbecause that governshow atoms interact
with each other
Knowing how electrons arearranged in an atom is
importantbecause that governshow atoms interact
with each other
Knowing how electrons arearranged in an atom is
importantbecause that governshow atoms interact
with each other
Knowing how electrons arearranged in an atom is
importantbecause that governshow atoms interact
with each other
Knowing how electrons arearranged in an atom is
importantbecause that governshow atoms interact
with each other
Knowing how electrons arearranged in an atom is
importantbecause that governshow atoms interact
with each other
Let’s say you have aroom with flies flyingaround in it
The flies are not justanywhere in the room.They are inside boxes inthe room.
You know where theboxes are, and youknow the flies areinside the boxes, but…
you don’t know exactlywhere the flies areinside the boxes
The room is an atomThe flies are electronsThe boxes are orbitals
The room is an atomThe flies are electronsThe boxes are orbitals
The room is an atomThe marbles are electrons
The boxes are orbitals
Science has determined where theorbitals are inside an atom, but itis never known precisely where theelectrons are inside the orbitals
the billions of interactions of atomsconstantly going on around youdepend on how the electrons
are arranged in each atom
the billions of interactions of atomsconstantly going on around you
depend on how the electronsare arranged in each atom
the arrangement of an atom’s electrons(its orbitals)
govern how that atom will interactwith other atoms
the billions of interactions of atomsconstantly going on around you
depend on how the electronsare arranged in each atom
the arrangement of an atom’s electrons(its orbitals)
govern how that atom will interactwith other atoms
If atoms did not interact with each other,you would not be sitting here reading this
Isotopes
General Chemistry
Molecules: Two or more atoms of the same or
different elements. Covalently bonded.
H2 =
General Chemistry
Compounds: Two or more atoms of different
elements.. May have covalent bonds OR ionic
bonds.
H2O =NaCl =
+ -
In an IONIC bond,electrons are lost or gained,resulting in the formation of IONS
in ionic compounds.
FK
FK
FK
FK
FK
FK
FK
FK+ _
FK+ _
The compound potassium fluorideconsists of potassium (K+) ions
and fluoride (F-) ions
FK+ _
The ionic bond is the attractionbetween the positive K+ ion
and the negative F- ion
Ionic Bonding
Sowhatarecovalentbonds?
In covalent bonding,atoms still want to achievea noble gas configuration(the octet rule).
But rather than losing or gainingelectrons,atoms now share an electron pair.
In covalent bonding,atoms still want to achievea noble gas configuration(the octet rule).
But rather than losing or gainingelectrons,atoms now share an electron pair.
The shared electron pairis called a bonding pair
Cl2
Chlorineforms
acovalent
bondwithitself
ClClHowwilltwochlorineatomsreact?
ClClEach chlorine atom wants to gain one electron to achieve an octet
ClClNeither atom will give up an electron –chlorine is highly electronegative.
What’s the solution – what can theydo to achieve an octet?
ClCl
Cl Cl
Cl Cl
Cl Cl
Cl Cloctet
Cl Cl
circle the electrons foreach atom that completestheir octets
octet
Cl Cl
circle the electrons foreach atom that completestheir octets
The octet is achieved byeach atom sharing theelectron pair in the middle
Cl Cl
circle the electrons foreach atom that completestheir octets
The octet is achieved byeach atom sharing theelectron pair in the middle
Cl Cl
circle the electrons foreach atom that completestheir octets
This is the bonding pair
Cl Cl
circle the electrons foreach atom that completestheir octets
It is a single bonding pair
Cl Cl
circle the electrons foreach atom that completestheir octets
It is called a SINGLE BOND
Cl Cl
circle the electrons foreach atom that completestheir octets
Single bonds are abbreviatedwith a dash
Cl Cl
circle the electrons foreach atom that completestheir octets
This is the chlorine molecule,
Cl2
O2
Oxygen is also one of the diatomic molecules
How will two oxygen atoms bond?
OO
OOEach atom has two unpaired electrons
OO
OO
OO
OO
OO
OO
Oxygen atoms are highly electronegative.
So both atoms want to gain two electrons.
OO
Oxygen atoms are highly electronegative.
So both atoms want to gain two electrons.
OO
OO
OO
OO
OO
OOBoth electron pairs are shared.
6 valence electronsplus 2 shared electrons
= full octet
OO
6 valence electronsplus 2 shared electrons
= full octet
OO
two bonding pairs,
OOmaking a double bond
OO=For convenience, the double bond
can be shown as two dashes.
OO
OO=This is the oxygen molecule,
O2
this is so
cool!!
Covalent bonding allows for an amazingly large variety
of compounds such as
small compounds likewater and carbon dioxide,
and ethanol (alcohol),
to larger compoundssuch as aspirin,
(21 atoms)
and the sex hormones
estradiol(estrogen)
and
testosterone,
(49 atoms)
(44 atoms)
to all of the 40,000 proteinsyou have in your body,
including
insulin,with 779 atoms,
and hemoglobin,with about 11,000 atoms!
There are an estimated1040 possible compounds
containing up to 50 atoms
The known chemical world,including natural andsynthetic compounds,
is far far far below 1% of that.
NATURE volume 442 p. 502 3 August 2006
As of 2007, there are about31,000,000 known compounds;
CAS registry: http://www.cas.org/cgi-bin/regreport.pl
About 12.5 million of thoseare commercially available.
Thousands of new compoundsare discovered or synthesized
every week!
Covalent Bonding
Electrons are shared between the two atoms