Transcript Unit 2 Chemistry of Life

Chapter 2 and 3
Estimated Time: 5 Days
Learning Goals:
1. Understand difference between Matter,
compounds, Elements and Atoms
2. Know and explain importance of
subatomic particles
3. Understand difference between different
types of bonds and chemical interactions
including hydrogen bonding and polarity of
water
4. Understand four emergent properties of
water (Hydrogen bonding, insulating factor,
Moderation of local temperature, and acting
as a solvent
5. Will be able to explain pH in terms of
acids, bases and buffers
Unit 2 Chemistry of Life
Sodium
+
Chlorine
Salt
Matter Review:
- Matter is anything that takes up
space
- Elements are the purest form of
matter
- Compounds are made up of one
or more elements
-Atoms are the basic unit of
elements that still retains all the
properties of that element
-Sub atomic particles
Proton = (+) located in nucleus
Electron = (-) located in orbitals
(give atoms bonding properties)
Nuetron = (=) located in nucleus
Atom Anatomy
-Electrons give elements bonding
properties
-Valence Electrons are outermost
electrons
-Electrons fill orbitals by:
(filling energy level, orbital, suborbital, and opposite
spins)
Atomic Number
(# of Protons)
Symbol
2
He
4.00
Atomic Mass
(# of Nuetrons + # of Protons)
Chemical properties of
elements depend on:
-number of valence electrons
-size of electron cloud
-distance between outer shell and nucleus
Atom to Atom Bonding
-All bonds are based on an electric charge between
atoms
-One atom steals an electron from another = Ionic bonds
-Atoms share electrons in their outer obritals (sp hybrids) =
Covalent bonds
-Polarity is when a molecule has a slight charge
-Nonpolar has no net charge (No free electrons)
Other weak bonds
Used primarily in structures of macromolecules like DNA and
Proteins
1. Hydrogen Bonds (Draw)
2. Non polar associations
3. Van der Waals Interactions
4. Sulfide Bridges
Covalent Bonding
Ionic Bonding
Bonding and Chemical
Attractions
Water is boring! Or is it?
There would be no life on earth if it wasn’t for the properties of water.
Properties of water
1. Water is polar and
repels nonpolar
2. Water forms hydrogen
bonds
3. The solid form is less
dense then the liquid form
4. High specific heat
(amount of heat required to raise
one gram one degree C.)
5. Is responsible for
creating aqueous
solutions
Emergent Property One: Cohesion
-Hydrogen bonding is responsible for cohesion and
adhesion
-Cohesion = hydrogen bonds holding together the
water molecules
-Adhesion = hydrogen bonds holding water to
another object
-Surface Tension is an example of how cohesion
works to hold the surface of a liquid together
Emergent Property Two: Moderation of
Temperature
-Specific heat of water is relatively high so it takes more heat to raise
temperature of a body of water.
-Specific heat of water plays a role in moderating ocean temperatures and
other large bodies of water like the greaat lakes.
-Water controls climate on nearby land masses as well as weather on all land
Ex. Lake effect snow
Emergent Property Three: Water as an
Insulator
-Density of water gets higher has as it cools
-Cooler, more dense, water holds more oxygen
-Ice becomes less dense then the liquid form of
water
-Ice cover allows for aquatic life to survive winters
-As the movement of molecules slow the
hydrogen bonds become more stable in a lattice
form
Emergent Property Four: Water
as an Solvent
-Hydrophilic substances like water or are polar
-Hydrophobic substances don’t like water or are nonpolar
-Water also is responsible for aqueous solutions
-Water’s solvent properties are responsible for cellular
organization or (Compartmentalization)
Water and pH
Potential
Hydrogen
Equilibrium Equation
-The pH scale is a logarithmic scale
-Neutral pH is 7 or has a hydrogen concentration of 10-7
- An acid has a pH of less then 7 or < 10-4
10-7
-An base has a pH of greater then 7 or < 10-7
pH = - log [H+]
ex.
4 = -log 10-4
[H+] [OH-] = 10-14
ex.
[10-4] [10-10] = [10-14 ]