Transcript Chapter 2 PP - jl041.k12.sd.us

Biochemistry Unit
Chapter 2: Chemical Foundations for Cells
You can be a chemist without knowing
biology, but you can’t be a biologist without
knowing chemistry.
I.
Basic Chemistry
A. Subatomic Particles
Charge
Mass
(AMU)
Neutron
Proton
Electron
Nearly 0
Location
I. Basic Chemistry
B. Atoms
• The smallest unit of matter that still retain
the properties of a given element.
• Too small to be seen by nearly all
microscopes/imaging technology.
• Each element is represented by a capital
letter, possibly followed by a lower case
letter. (e.g. H, O, C, Ag, Au)
Basic Chemistry
B. Atoms
• Structure: Nucleus (no membrane or
surrounding core) and electron clouds.
• Just know first three clouds hold:
>2 electrons, cloud 1
>8 electrons, cloud 2
>8 electrons, cloud 3
Outer cloud call valence cloud (it reacts
with other atoms)
Basic Chemistry
C. The Periodic Table
1. Columns represent # of valence
electrons (ignore dip)
# of Valence Electrons
C – Carbon
Na – Sodium
Si – Silicon
Cl - Clorine
Basic Chemistry
C. The Periodic Table
2. Rows equal number of electron clouds.
1
2
3
4
Number of Clouds:
Li – Litium
H – Hydrogen
Si – Silicon
Ca - Calcium
Basic Chemistry
C. The Periodic Table
3. Reading the Details:
Atomic Number - # of
Protons
Atomic Mass - # of
Protons + # of
Neutrons
Atomic Symbol – Only 1
upper case letter
Complete:
P
O-16
H–2
H-3
N
E
Basic Chemistry
C. The Periodic Table
4. Rush Limbaugh Rule (Boint’s favorite part
of chemistry): All electrons what to be like
those on the FAR RIGHT (Noble gases).
A full outer cloud is known as a stable
octet (having 8 electrons).
Basic Chemistry
C. The Periodic Table
5. Left side of table
are metals
Right side are
nonmetals
Along stair are the
metalloids
Basic Chemistry
D. Molecules
1. Two or more atoms chemically
combined.
2. Mixtures (salt and water) are simply
physically mixed, not chemically
combined.
3. Molecules are written with no space
between atomic symbols (e.g. H2O or
NH4)
II. Key Concepts in Chemistry
A. Ions: Atoms with net electric charge.
Balanced atom/molecule: # of electrons
and protons equal.
Ion: Unequal # electrons and protons.
Polyatomic Ion: Two or more atoms
combined, with the molecule/compound
having a overall negative charge. (NO3-)
II. Key Concepts in Chemistry
B. Isotopes: Atoms of the same element
with different numbers of neutrons, thus
different atomic masses.
Number of protons is ALWAYS constant
for an element.
Number of neutrons can vary.
Three Isotopes of Hydrogen
Protons?
Neutrons?
AMUs?
Chemical
Notation?
II. Key Concepts in Chemistry
C. Radioactivity: An atom with an unstable
nucleus that undergoes decay (lost of
subatomic particles) as it transitions to a
stable state.
Decay of trilium: 3H1 => 3He2 + 0e-1
III. Electrons
• Negligible mass
• Exist in clouds of probability, not defined
‘shells’! (ignore the book when they use
this term)
• Basis of Bonds
III. Electrons
A. Ionic Bonds: Strong bonds between a
metal and nonmetal
• Two ions joined together
• Electrons ‘donated’ not ‘shared’
• The strongest of the bonds
• Ionic compounds have high melting
points and crystal structures
III. Electrons
B. Covalent Bonds: Bond between
nonmetals in which electron pairs are
‘shared.’
• Not as strong as ionic bonds
• Compounds form discrete molecules
• Molecular formula (H O)
2
III. Electrons
B.1. Polar Covalent: A covalent bond in
which electrons are unevenly shared,
resulting in a electrically balanced
molecule (equal number of protons and
electrons) but with charged ends.
• Involves (mainly) F, Cl, O due to their
highly electronegative properties
III. Electrons
B.1. Polar Molecules
III. Electrons
B. 2. Hydrogen bonds: Notably strong polar
bonds due to the solo proton in hydrogen’s
nucleus.