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2013 s bio 101 chapter 2 basic chemistry
1. Objectives for this week…
Generate an empirically evidenced and logical argument.
Distinguish a scientific argument from a non-scientific argument.
Recognize methods of inquiry that lead to scientific knowledge.
List features that distinguish living organisms from nonliving
matter.
Explain what is meant by the term diversity, and speculate about
what caused the great diversity of life forms on Earth.
List as many steps of the scientific approach to understanding a
problem as you can.
Know the various types of chemical bonds, the
circumstances under which each forms, and the
relative strength of each type
Understand the essential chemistry of water, the
relationships of acids, bases, and salts.
2.
3. Why do we need to learn about
Chemistry?
Chapter 2
Basic Chemistry
Chemistry: “The study of matter
& the changes it undergoes.”
-Chang, R. (2007). Chemistry. 9th ed.
McGrawHill: New York
7. What are we going to talk about
today?
Chemical elements
Compounds and molecules
Chemistry of water
Acids and bases
8. Protons
Electrons
Neutrons
Chemical Elements
• Matter: anything that takes up space and has
mass (solids, liquids, gases)
• All matter is made of elements: cannot
be broken down
Oxygen
An element!
+
+
+
+
+ +
+
+
-
-
--
-
-
-
-
Atom: smallest unit of an
element
Water
Not an element!
Hydrogen
John Dalton
11. Electrons are
attracted to the
positively charged
nucleus
Chemical Elements
(-)(+)
Most stable
Less stable
Valence shell: Outer electron
shell
Valence electrons: # of
electrons in valence shell
Octet rule: outer shell is most
stable with 8 electrons
12. Chemical Elements
• Isotopes
– Same # of protons and
electrons
– Different # of neutrons
• Ions
– Different # of electrons
– Have charges, instead
of being neutral
Na Na+
13. Chemical Elements
• Way to organize the
elements
• Groups - similar
characteristics
– Same valence electrons
• Periods – same #
valence shells
• Atomic mass
– Average mass for all the
isotopes
– Slightly different than
mass number
Periodic Table
16. Chemical Elements
• Radioactivity - releases
energy (as well as
other particles)
• Radioactive isotopes
can be used as medical
tracers (low levels)
• High levels can be used
to kill bacteria and
cancer
17. What are we going to talk about
today?
Chemical elements
Compounds and molecules
Chemistry of water
Acids and bases
18. Compounds and Molecules
• Compound vs.
molecule
• Compound 2 different
elements
• Molecule has same
elements
• In Biology, everything
is a molecule!
http://dl.clackamas.edu/ch104-03/molecule.htm
Water
Molecular
Oxygen
19. Compounds and Molecules
• Ionic Bonding
– Transfer of electrons
from one atom to
another
– Causes (+) and (-)
charged ions
– Attracted to each other
– Salts: solid substances
that usually separate and
exist as individual ions in
water
20. Compounds and Molecules
• Covalent Bonding
– Two atoms share
electrons to fill outer
electron shell
– Single, double, triple
bonds
– Non-polar covalent bond
= equal electron sharing
– Polar covalent bond =
unequal electron sharing
water!!
21. Which do you think is the strongest, ionic
or covalent bonds? Why?
22. What are we going to talk about
today?
Chemical elements
Compounds and molecules
Chemistry of water
Acids and bases
23. Chemistry of Water
Water (H2O)
is polar
covalent
Oxygen is very electronegative
Hydrogen
bonding
between
molecules
24. The discovery of liquid water under the frozen
surface of a distant moon in our solar system
has caused scientists to speculate on the
possibility of life on that moon. Researchers
hold no hope of any life form existing on any
planet or moon in the absence of water.
Why?
25. Chemistry of Water
• Properties
1. High heat capacity
2. High heat of evaporation
3. Solvent
4. Cohesion & adhesion
5. Frozen water is less dense than liquid water
28. Chemistry of Water
Water is a Solvent
• Universal solvent
• Hydrophilic –
molecules that can
attract water (ions,
polar molecules)
• Hydrophobic –
molecules that cannot
attract water
(nonpolar molecules,
neutral atoms)
31. Review: Chemistry of Water
• Polar covalent bond
within the molecule
• Hydrogen bonds
between molecules
• 5 Properties
1. High specific heat
2. High heat of
vaporization
3. Is a solvent
4. Cohesion and
adhesion
5. Frozen water is less
dense than water
32. What are we going to talk about
today?
Chemical elements
Compounds and molecules
Chemistry of water
Acids and bases
33. Acids and Bases
When water dissociates (ionizes)
equal # of hydrogen ions and
hydroxide ions
Only a few at a time do this
34. Acids and Bases
Acids
• Dissociate in water
releasing H+
• Strong acid almost
completely dissociates
HCl H+ + Cl-
Bases
• Uptake H+ or release
OH-
• Strong base almost
completely dissociates
NaOH Na+ + OH-How do we
measure
this?
35. Acids and Bases
• pH scale: measurement
scale for hydrogen ion
concentration
• >7 basic
• <7 acidic
• =7 neutral
• Log scale
– each increase in
number = 10X increase
100X more acidic
than water
10,000,000X more
acidic than water
36. Acids and Bases
• Buffers: chemical or
combination of
chemicals that keep pH
within normal limits
– Blood pH needs to stay
about 7.4
– At 7, acidosis
– At 7.8, alkalosis
H2CO3 H+ HCO3
-
dissociates
re-forms
37. Acids and Bases
• Acid precipitation (deposition) has a pH <5
• Sulfur dioxide and nitrogen oxides from fossil
fuel emissions such as coal, oil, and gasoline
• Lakes, forests, structures
38. What are we going to talk about
today?
Chemical elements
Compounds and molecules
Chemistry of water
Acids and bases
Any Questions?
39. Review Questions
About 25 of the 92 natural elements are known to
be essential to life. Which four of these 25
elements make up approximately 96% of living
matter?
A) carbon, sodium, chlorine, nitrogen
B) carbon, sulfur, phosphorus, hydrogen
C) oxygen, hydrogen, calcium, sodium
D) carbon, hydrogen, nitrogen, oxygen
E) carbon, oxygen, sulfur, calcium
40. Review Questions
How do isotopes of the same element differ
from each other?
A) number of protons
B) number of electrons
C) number of neutrons
D) valence electron distribution
E) amount of radioactivity
41. Review Questions
A covalent chemical bond is one in which
A) electrons are transferred from one atom and to
another atom so that the two atoms become
oppositely charged.
B) protons and neutrons are shared by two atoms.
C) outer-shell electrons of two atoms are shared.
D) outer-shell electrons of one atom are transferred to
the inner electron shells of another atom.
E) the inner-shell electrons of one atom are transferred
to the outer shell of another atom.
45. Resources
• Bombardier beetle
– http://www.pnas.org/content/96/17/9705.full
• History of the Atom
– http://www.chemheritage.org/discover/chemistry
-in-history/themes/index.aspx
