Transcript Hydrogen Bonding

Matter is recycled and rearranged
for living organisms
• Living matter is made up
of different substances.
CO2
• Example of substances:
pure CO2, glucose, pure
salt, H2O…..
glucose
Atoms, Molecules and Compounds
Atoms - Smallest unit of an element (with properties
of that element)
• Nucleus - dense center containing:
– Protons - positively charged
particles
– Neutrons - particles with no
charge
• Electrons (e-) - small, negatively
charged particles that orbit nucleus
in clouds or shells (2, 8, 8)
– Valence - found in outermost
energy level
e-
How many total e-? How
many valence e-? What
element?
Lewis Dot Diagrams
• The inner shells are not
involved in bonding
• Carbon is in group 14, so
that means 4 valence
electrons
• We often write the element
symbol and only the valence
electrons
You try…
What does the Lewis dot
diagram look like for
Oxygen?
What does the Lewis dot
diagram look like for
Sodium?
Hydrogen?
How about Lithium?
Why are they all the same?
Na
H
Li
Ions = electrically charged matter
OIL RIG Oxidation is losing, Reduction is gaining
• Ions form when electrons are lost or gained.
• Ionic bonds form when a positive ion is attracted
to a negative ion.
Covalent
bond = two
atoms sharing
electrons
• “Strong”
• Relatively stable
• H, O and N can
readily form
covalent bonds
with C.
Chemical Equations
Reactants
2H2O2
Hydrogen peroxide
→
Products
2H2O + O2
coefficient
Water & Oxygen
Subscripts
coefficient
Yield sign
•
•
•
•
How many hydrogen atoms are in the reactants?
How many hydrogen atoms are in the products?
How many water molecules are produced?
How many molecules of hydrogen peroxide are
broken down?
Chemical reactions
6CO2 + 6H2O  C6H12O6 + 6O2
• Lead to changes in substance or matter.
• Occurs when electrons are transferred
between two atoms (lost, gained or
shared)
The 17 essential elements in plants
(autotrophs)…
CHOPKINS Ca Fe Mg B Mn Cu Zn Mo Cl
Carbon, Hydrogen, Oxygen, Phosphorous, Potassium, Iodine,
Nitrogen, Sulfur, Calcium, Iron, Magnesium, Boron, Manganese,
Copper, Zinc, Molybdenum, Chlorine
C HOPKINS Café Managed by my cousin Mo Cline
• 96% of living matter:
C, H , O, and N
• 4% of living matter:
Ca, K, P, S, Na, Cl,
Mg, Fe, and trace
elements
Hydrogen Bonding
• Weak bonds between
a hydrogen of one
molecule to an
adjacent negative
molecule
• Ex: attraction between
water molecules.
Properties of Water
Check for Understanding
• What is the name of the
compound in the bottle?
• What is the molecular
formula?
• What is the structural
formula?
• How many molecules of
the substance are in the
bottle?
• How would you calculate
this?
Water
The universal solvent in living things
which makes up over 90% of cells and the
majority of Earth
Why water works well in living
things
1. Water is Polar and is really good at
dissolving substances
2. Water is needed for all cellular chemistry
3. Water molecules adhere to some things
4. Water molecules stick together
5. Water molecules form surface tension
6. Ice floats
7. Water has a high specific heat
Universal solvent
• Water is a solvent
(it dissolves stuff
for living things)
• Water can
dissociate (break
apart) most ionic
compounds such
as salts.
• Solutes + Solvent
= Solutions
The Lewis dot structure for water shows the electron from hydrogen
and an electron from oxygen being shared in a covalent bond.
The other four valence electrons in oxygen are in pairs at the bottom.
The lines are a short-hand version of the two dots representing the covalent bonds.
+
+
-
Water is a Polar
molecule
• Polar or angular molecules
have a non-linear shape.
• For example, water (H2O),
has an angle of about 105°.
• A water molecule has two
pairs of bonded electrons
and two unshared lone
pairs.
Create a Polar Water molecule
• On page 2 (left facing page side) of your
learning journal and using construction
paper, create a water molecule. Try to
mimic the 105° angle using a protractor if
possible.
• Show the covalent bonds as solid lines
between the Oxygen and the Hydrogens.
Page 2
+
+
• The water molecule is Polar because……
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Page 3
Hydrogen Bonding
• Hydrogen bonds show the attraction
between ….
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Polarity
• Water molecules are polar.
• Polarity: one end of the molecule is
positively (+) charged and the other end
negatively (-) charged
• Polarity causes hydrogen bonding
between water molecules
Cohesion
• Water
molecules
are attracted
to each other.
• Water
molecules
“stick”
together.
Hydrogen Bonds
Cohesion causes Surface Tension
• Surface Tension
• Water molecules tend
to stick together,
forming a sort of
“skin”
• Some animals can
use this “skin” as
surface on which it
can walk.
Water strider spider
• What properties of water makes a belly
flop hurt so bad?
• http://www.youtube.com/watch?v=N8gave
vFX-0&feature=fvsr
Surface Tension
Capillary action in Plants
Adhesion
• Water molecules are
attracted to surfaces
that have charges
(hydrophilic).
• Water molecules are
repelled from
surfaces that have no
charge (hydrophobic).
Density
• Water becomes less dense (more space
between molecules) when it freezes.
Properties of water’s density
• Ice floats, creating buffer from cold air,
enabling organisms to still survive
underneath the frozen surface.
Why is carbon the basis for life?
• It has 4 electrons in its outer
(valence) electron shell.
• Octet rule: The most stable
elements have 8 electrons
in its outer shell, with few
exceptions.
• Carbon forms 4 covalent
bonds to fulfill the octet rule.
• Therefore, Carbon is really
good at forming rings and
chains
Some Carbon Compounds
Section 2-3
Methane
Acetylene
Butadiene
Benzene
Isooctane
Organic compounds
• Always contain carbon (carbon can bond
with many other elements)
• Small units called monomers join together
to form polymers
Making polymers
• Think of molecules as “mers”
• When 2 monomers join, they form dimers.
• Adding more monomers form polymers.
 1 “mer” = monomer
 2 “mers” (mer+mer) = dimer
 3 or more “mers” (mer+mer+mer+mer) =
polymer
4 Important carbon
polymers & complex molecules
1.
2.
3.
4.
Carbohydrates
Proteins
Lipids
Nucleic acids
Dehydration synthesis • Joining monomers
into polymers while
taking away water
molecules
• A-OH + B-HAB +
H2O
• Dehydrate – to take
away water
• Synthesis – to make
Carbohydrates – sugars, starch,
cellulose, chitin
• Function: quick energy
(4 calories per gram)
• Building blocks:
Monosaccharides or simple sugars like
glucose C6H12O6
• Carbohydrates provide cellular energy
• Cell Membrane functions and support
• Examples:
– Monosaccharides (glucose, fructose, etc)
– Disaccharides (sucrose, lactose, etc)
– Polysaccharides (starch, cellulose, glycogen, chitin)
Section 2-3
Starch
Starch
Glucose
Proteins – used for structure and
function
• Purpose: can be used for energy (4 calories per gram) but
mostly used for cell structure and metabolism
(enzymes)
• Building blocks: amino acids (20) held together by
peptide bonds
• Sometimes very large, complex molecules
Amino Acids
Section 2-3
Amino group
Carboxyl group
General structure
Alanine
Serine
ATP Synthase
Hormones
Enzymes
Antibodies
Hemoglobin
Muscle fibers
Lipids – fats, oils, waxes, sterols
• Function: long term stored energy
• (9 calories per gram)
• Provides insulation & cushioning
• Does NOT have monomer/polymer
structure
• Examples:
– Saturated (animal fats)
– Unsaturated (plant oils)
– phospholipids are the basic structure of cell
membranes.
– Steroids are signal chemicals to initiate a process
in the body
Examples of Sterols
•
•
•
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cholesterol
steroids
estrogen
testosterone
Click on the testosterone molecule
Lipid Structure
Some examples of lipids
Lipids are a vital component of cell
membranes
Nucleic acids
• Functions: store &
translate hereditary
information.
• Building blocks:
Monomers of
nucleotides (sugar,
phosphate, base)
• Examples:
– DNA (stores code)
– RNA (translates code to
protein)
Parts of a Nucelotide
• Phosphate
• Sugar
• Nitrogen containing Base
What does DNA do?
• DNA does NOT govern cell activity
directly!!
• “DNA is the code for the making of
proteins used for structure and function”.
The 4 Bases found in DNA
The 4 Bases found in DNA as Nucleotides
DNA Structure
Organic
macromolecule
Monomer
(building block)
Polymer
Carbohydrates
Monosaccharide
Polysaccharides
4 calories per gram
(ex: Glucose)
(ex: sugars, starch,
cellulose, glycogen,
chitin, etc.)
Proteins
Amino acids
Structural proteins
and enzymes
9 calories per gram
Glycerol and fatty
acids
Fats, oils, waxes,
sterols
Nucleic acids
Nucleotides
DNA, RNA
4 calories per gram
Lipids
Heredity information
(Types)