Basic Chemistry for Biology

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Basic Chemistry for Biology
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Atoms(Take Notes on All of This Stuff)

• Atoms are the smallest unit of an element.
• Elements are things like Oxygen, Carbon, Iron,
  Aluminum, Helium.
• Two parts to an atom the nucleus electron
  shell (that is around the nucleus).
• The number of Protons defines an atom.
• Iron has a different number of protons than
  aluminum.
• Protons exist in the Nucleus of the atom.
• Protons are positively () charged particles.
• Neutrons have no charge, but are the same size as
  a proton.
• Electrons orbit around the nucleus of the atom in
  Electron Shells.
• Electrons are negatively charged particles.

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What is an atom?

• Something really, really tiny.
• The smallest unit of an element.
• The smallest unit of a molecule.
• The smallest unit of a compound.

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What is a good defintion of an element?

• A substance that cannot be broken down further by
  physical means.
• A substance that cannot be broken down further by
  chemical means.
• A substance that cannot be broken down further by
  nuclear means.
• A substance that can combine with another
  substance.

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Protons, Neutrons Electrons oh my!

• Mass of the atomic particles are measured in
  Atomic Mass Units (a.m.u.)
• An a.m.u. is equal (by definition) to the mass of
  one proton.
• A Neutron also has a mass of 1 a.m.u.
• An Electron weighs next to nothing, for our
  purposes, has a mass of 0 a.m.u.

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Summary Atomic Particles
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Sodiums atomic number is 11 an its atomic mass
is 22. How many protons does sodium have?

• 11
• 22
• It depends on its charge.

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How many electrons does sodium have?

• 11
• 22
• It depends on its charge.

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If a carbon atom has an atomic number of 6 and an
atomic mass of 13, how many neutrons does it have?

• 6
• 7
• 13
• It depends on its charge.

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Bohr Model of an Atom

• The Bohr Model (after Neils Bohr) shows how
  protons, neutrons electrons all fit together.
• P Proton, N Neutron, e- Electron

e-
If an atom has the same number of electrons as
protons, then it is neutral.
Most of the atom is empty space! (so, most of you
is empty space too!)
e-
N
P
N
N
e-
N
N
P
P
P
e-
N
P
P
e-
This atom has 6 protons, 6 neutrons and 6
electrons It is carbon is neutral.
e-
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In the Bohr model of the atom, the electrons are
located

• In the nucleus.
• Around the outside.
• It depends on the charge.

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In the Bohr model of the atom, the protons are
located

• In the nucleus.
• Around the outside.
• It depends on the charge.

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In the Bohr model of the atom, the neutrons are
located

• In the nucleus.
• Around the outside.
• It depends on the charge.

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A calcium atom has 20 protons, 21 neutrons and 18
electrons. What is its charge?

• -2
• -1
• 0
• 1
• 2
• Not enough information

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A calcium atom has 17 protons, 18 neutrons and 18
electrons. What is its charge?

• -2
• -1
• 0
• 1
• 2
• Not enough information

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Lets Put Some Atoms Together

• Molecule
• Two or more atoms held together by a covalent
  bond.
• A bond is covalent when the electrons are shared.
• An Ionic Bond exists when electrons are not
  shared, but stolen.
• Compound
• Two or more elements that are chemically
  combined.
• May use covalent or ionic bonding.

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The four bonds shown here are
http//www.gcsechemistry.com/Methane-Molecule.gif

• Covalent
• Ionic
• Hydrogen

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The bond shown here is
http//lc.brooklyn.cuny.edu/smarttutor/core3_21/im
ages/nature/9.a.Ionicbond-nacl.gif

• Covalent
• Ionic
• Hydrogen

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Hydrogen Bonds

• Some molecules, like water (H2O), have a slight
  negative charge on one side and a slight positive
  charge on the other.
• When the positive side of one water molecule
  meets the negative side of another water
  molecule, they form a weak bond A Hydrogen Bond.

H
-

H
O
-
O

H

H
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The bond between the hydrogen and the oxygen
represents a(n)
http//faculty.clintoncc.suny.edu/faculty/Michael.
Gregory/files/Bio20101/Bio2010120Lectures/chemi
stry/img018.gif

• Covalent bond
• Ionic bond
• Hydrogen bond

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The bond between the water molecules (dashed
line) represents a(n)
http//www.lbl.gov/images/MicroWorlds/H2OH-bond.gi
f

• Covalent bond
• Ionic bond
• Hydrogen bond

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Now We Can Make Bigger Stuff

• Carboyhydrates
• Molecules composed of monosaccharide (simple
  sugar) subunit(s)
• Examples Starch, glycogen, fructose, sucrose
• Proteins
• Large complexes of amino acids subunits
• Examples Muscle, enzymes
• Lipids
• Large complexes of fatty acid subunits
• Examples Oil, fat
• Nucleic Acids
• Large complexes of nucleotide subunits
• Examples DNA, RNA