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 electrons 6 protons 6 neutrons Carbon 12

Electrons are part of what makes an atom an atom

Electrons are part of what makes an atom an atom atom But where exactly are the electrons inside an atom?

Orbitals are areas within atoms where there is a high probablility of finding electrons.

Knowing how electrons are arranged in an atom is important because that governs how atoms interact with each other

Knowing how electrons are arranged in an atom is important because that governs how atoms interact with each other

Knowing how electrons are arranged in an atom is important because that governs how atoms interact with each other

Knowing how electrons are arranged in an atom is important because that governs how atoms interact with each other

Knowing how electrons are arranged in an atom is important because that governs how atoms interact with each other

Knowing how electrons are arranged in an atom is important because that governs how atoms interact with each other

Knowing how electrons are arranged in an atom is important because that governs how atoms interact with each other

Let’s say you have a room with flies flying around in it

The flies are not just anywhere in the room. They are inside boxes in the room.

You know where the boxes are, and you know the flies are inside the boxes, but…

you don’t know exactly where the flies are inside the boxes

The room is an atom The flies are electrons The boxes are orbitals

The room is an atom The flies are electrons The boxes are orbitals

The room is an atom The marbles are electrons The boxes are orbitals Science has determined where the orbitals are inside an atom, but it is never known precisely where the electrons are inside the orbitals

the billions of interactions of atoms constantly going on around you depend on how the electrons are arranged in each atom

the billions of interactions of atoms constantly going on around you depend on how the electrons are arranged in each atom the arrangement of an atom’s electrons (its orbitals) govern how that atom will interact with other atoms

the billions of interactions of atoms constantly going on around you depend on how the electrons are arranged in each atom the arrangement of an atom’s electrons (its orbitals) govern how that atom will interact with 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. H 2 =

General Chemistry  Compounds: Two or more atoms of different elements.. May have covalent bonds OR ionic bonds. H2O =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 fluoride consists of potassium (K + ) ions and fluoride (F - ) ions

FK + _ The ionic bond is the attraction between the positive K + ion and the negative F - ion

Ionic Bonding

So what are covalent bonds?

In covalent bonding, atoms still want to achieve a noble gas configuration (the octet rule). But rather than losing or gaining electrons, atoms now share an electron pair.

In covalent bonding, atoms still want to achieve a noble gas configuration (the octet rule). But rather than losing or gaining electrons, atoms now share an electron pair. The shared electron pair is called a bonding pair

Cl 2 Chlorine forms a covalent bond with itself

Cl How will two chlorine atoms react?

Cl Each chlorine atom wants to gain one electron to achieve an octet

Cl Neither atom will give up an electron – chlorine is highly electronegative. What’s the solution – what can they do to achieve an octet?

Cl

octet

Cl circle the electrons for each atom that completes their octets octet

Cl circle the electrons for each atom that completes their octets The octet is achieved by each atom sharing the electron pair in the middle

Cl circle the electrons for each atom that completes their octets The octet is achieved by each atom sharing the electron pair in the middle

Cl circle the electrons for each atom that completes their octets This is the bonding pair

Cl circle the electrons for each atom that completes their octets It is a single bonding pair

Cl circle the electrons for each atom that completes their octets It is called a SINGLE BOND

Cl circle the electrons for each atom that completes their octets Single bonds are abbreviated with a dash

Cl circle the electrons for each atom that completes their octets This is the chlorine molecule, Cl 2

O2O2 Oxygen is also one of the diatomic molecules

How will two oxygen atoms bond? OO

OO Each 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

O O Both electron pairs are shared.

6 valence electrons plus 2 shared electrons = full octet O O

6 valence electrons plus 2 shared electrons = full octet O O

two bonding pairs, O O making a double bond

O O = For convenience, the double bond can be shown as two dashes. O O

O O = This is the oxygen molecule, O 2 this is so cool! !

Covalent bonding allows for an amazingly large variety of compounds such as

small compounds like water and carbon dioxide,

and ethanol (alcohol),

to larger compounds such as aspirin, (21 atoms)

and the sex hormones estradiol (estrogen) and testosterone, (49 atoms) (44 atoms)

to all of the 40,000 proteins you have in your body, including

insulin, with 779 atoms,

and hemoglobin, with about 11,000 atoms!

There are an estimated possible compounds containing up to 50 atoms The known chemical world, including natural and synthetic compounds, is far far far below 1% of that. NATURE volume 442 p August 2006

As of 2007, there are about 31,000,000 known compounds; CAS registry: About 12.5 million of those are commercially available. Thousands of new compounds are discovered or synthesized every week!

Covalent Bonding  Electrons are shared between the two atoms