Download Lecture 0930 1001

Life is diverse
 Life in the biosphere and in an ecosystem is diverse
 Diversity is the hallmark of life
 The diversity of known life includes :
 > 1million insects
 290,000 plants
 52,000 vertebrates
 Estimates of the total diversity range from 10 million to over 100 million
species
Studying diverse life requires a
method of grouping
Taxonomy: is the science of grouping and classifying biological life.
The three major domains of
life
Kingdom Fungi
DOMAIN EUKARYA
Kingdom Plantae
Kingdom Animalia
Protists (multiple kingdoms)
Major themes in Biology
 Evolution
 Natural selection results in evolution
 Relationship between structure and function
 Given a structure, we can predict function
 Information flow
 In all life information is passed from generation to generation
 Energy and matter transformation
 Living things change energy and matter
 Enter connection between systems
 Life is interconnected from the Biosphere to atoms
Evolution: Darwin and his
Galapagos island adventure

Darwin’s theory of speciation “The origin of species by means of Natural
Selection” 1859
Theories from Darwin's observation
 Natural selection
 Descent with modification
Natural selection alters population
attributes
Random population
Selection process
Change in population
composition
New population
Artificial selection affects population composition
Domesticated dogs descended from wolves
Domesticated dogs
Gray wolves
HOME WORK
Look for an artificial selection in your
surrounding and describe
1. What was the selection?
2. How it altered the population?
3. Pros and cons of the selection.
Essential Chemistry for Biology
Atoms and Molecules
Matter: Elements and Compounds
What is Matter? is anything that occupies space and has mass.
Physical states of mater:
Solid
example:
Ice
Liquid
Water
Gas
Vapor
Matter: Elements and Compounds
What is Matter? is anything that occupies space and has mass.
Physical states of mater:
Solid
example:
Ice
Liquid
Water
Gas
Vapor
Matter is composed of chemical elements.
Elements are substances that cannot be “broken down” into other
substances.
There are 92 naturally occurring elements on Earth.
All of the elements are listed in the periodic table.
6
C
12
8
O
Oxygen
15.994
 Twenty-five elements are essential to life.
 Four elements make up about 96% of the weight of the human body:
Oxygen
Carbon C: 18.5%
Carbon
Oxygen O:
65.0%
Hydrogen
Calcium Ca: 1.5%
Nitrogen
Phosphorus P: 1.0%
Potassium K: 0.4%
Sulfur S: 0.3%
Sodium Na: 0.2%
Chlorine Cl: 0.2%
Hydrogen H:
9.5%
Nitrogen N:
3.3%
Magnesium Mg: 0.1%
Trace elements: less than 0.01%
Boron B
Chromium Cr
Cobalt Co
Copper Cu
Fluorine F
Iodine I
Iron Fe
Manganese Mn
Molybdenum Mo
Selenium Se
Silicon Si
Tin Sn
Vanadium V
Zinc Zn
Trace elements does not imply
unimportance
Lack of iodine can cause goiter
Elements can combine to form
compounds
Compounds are substances that contain two or more
elements in a fixed ratio.
Common compounds include
 NaCl (table salt)
1:1 combination of Sodium “ion” and “chloride
 H2O (water)
1:2 combination of Hydrogen and oxygen
Atoms:
 Each element consists of one kind of atom.
Example (elemental Hydrogen exist as H2 gas)
An atom is the smallest unit of matter
Atoms are the building blocks of all matter
Atoms retains the properties of an element.
Atoms:
 Each element consists of one kind of atom.
Example (elemental Hydrogen exist as H2 gas)
An atom is the smallest unit of matter
Atoms are the building blocks of all matter
Atoms retains the properties of an element.
 Atoms are composed of subatomic particles.
A proton is positively charged.
An electron is negatively charged.
A neutron is electrically neutral.
Atoms:
 The denser sub-particles form the nucleus of an atom:
 Protons are positively charged (+) mass=1.0073 atomic mass unit (amu)
 Neutrons are particles that carry no charge and determine the atom’s
mass.
mass=1.0087 amu
 Protons and neutrons are similar size and mass.
 Protons determine the identity of an atom
 Electrons are negatively charged particles (–)
mass=0.0005486 amu
 Compared to protons and neutrons,
very small in size .
 Determine reactive state of an atom
 Surround the nucleus of an atom
Atoms: Summary
Proton
• Positive charge
• Determines element
Neutron
• No charge
• Determines isotope
Electron
• Negative charge
• Participates in chemical
reactions and determine
chemical behavior
Atom
Nucleus
• Consists of neutrons
and protons
Representation of an Atom
Electron Density cloud from
experiment
Graphic representation of an Atom
planetary, or electron-shell model.
Nucleus
Electrons
Modeled elements
Can you name some problems
with the planetary representation?
Representation of an Atom
Electron Density cloud from
experiment
Graphic representation of an Atom
planetary, or electron-shell model.
Nucleus
Electrons
Electron cloud model
Modeled elements
What can we learn from the
periodic table?
1
H
Hydrogen
1.00794
Atomic number: is the number of protons or neutrons
Elemental Symbol
Atomic mass: is the sum of the number of protons and
neutrons (what about mass of electrons?)
Electrons are arranged in energy
shells
First electron shell
can hold 2 electrons
Outer electron shell
can hold 8 electrons
Electron
Hydrogen H
Atomic number = 1
Carbon C
Atomic number = 6
Nitrogen N
Atomic number = 7
Oxygen O
Atomic number = 8
The Octet Rule
 Atoms with their outer most shell complete (2 for the first shell or 8 for
the outer most shell) are stable. = The octet Rule
Hydrogen (H)
Atomic number = 1
Oxygen O
Atomic number = 8
 Valence electrons are those in the outermost level of an atom.
 To satisfy the Octet Rule, atoms interact using Valence electrons
either losing or gaining electrons.
 Atoms that gained or lost an electron are charged and called ions
Chemical Bonds
 Two or more elements can combine to form molecules. They are
held together by chemical bonds.
Outer shell
has 1 electron
The outer electron is stripped
from sodium and completes
the chlorine atom’s outer shell
Complete
outer shells
Outer shell
has 7 electrons
Na
Sodium atom
Cl
Chlorine atom
Na
Sodium ion
Cl
Chlorine ion
Sodium chloride (NaCl)
The attraction
between the
ions—an ionic
bond—holds
them together
Chemical Bonds
Outer shell
has 1 electron
The outer electron is stripped
from sodium and completes
the chlorine atom’s outer shell
Complete
outer shells
Outer shell
has 7 electrons
Na
Sodium atom
Cl
Chlorine atom
Na
Sodium ion
Cl
Chlorine ion
The attraction
between the
ions—an ionic
bond—holds
them together
Sodium chloride (NaCl)
Ionic Bonds : a chemical bond between charged elements
Covalent Bonds: a chemical bond between atoms sharing electrons
Hydrogen Bonds: is an attraction between two polar molecules
Covalent Bonds
 A covalent bond forms when two atoms share one or more pairs of outer-shell
electrons.
Oxygen O
Atomic number = 8
Hydrogen H
Atomic number = 1
Water
 Atoms held together by covalent bonds form a molecule.
 The number of covalent bonds an atom can form is equal to the number of
additional electrons needed to fill its outer shell.
Covalent Bonds
single bonds: = bond between
atoms share one pair of e-
 double bonds= bonds between
atoms sharing two pairs of e-
 triple covalent bond: bonds
between atoms sharing three
pairs of e-.
In covalent bonds, electrons are not
always shared equally
Non-Polar molecule
Polar molecule
slightly 
slightly 
H
H
O
slightly –
CH4 (methane)
H2O (water)
Polar molecules form Hydrogen Bond
Water is a compound in which the electrons in its
covalent bonds are shared unequally.
Hydrogen bond
Properties of Water
 Cohesion: is the attraction between
molecules of water.
 Adhesion is the attraction of water to the
molecules of the container or tube it is in.
 High specific heat capacity is the
capacity to hold energy
Properties of Water
 Ice Floating.
 When cold, water molecules move
apart, forming ICE.
 If ice did not float, ponds, lakes, and
even the oceans would freeze solid.
 Water is the universal solvent.
The dissolving agent is the solvent.
The dissolved substance is the solute.
When a solute is dissolved with water it is
called Aqueous Solution
Per unit volume, liquid
water holds more
molecules than ICE
Work in groups
For the following atoms:
1.
Draw the planetary atomic representation
2.
Indicate valence electrons
3.
Form compounds by combining elements
4.
Discuss the type of bond
Hydrogen, Helium, Sodium,
Carbon, Nitrogen, Oxygen
Lithium, Florine, Chlorine,
Magnesium
Home work
Isotope forms of elements are important in science and medicine
 Look for application of isotope form of an element used in
science and medicine
 Describe the kind of application
 Determine the number of electrons, protons, and neutrons
 Draw a planetary description of the isotopic element