TERMINOLOGY
Chemistry study of compositionof matter and processes that build up and break down substances.
Biochemistry study of chemical processes that help to sustain living things
3 SUBATOMIC PARTICLES
• Nucleus (Center)
Positive protons
Neutral neutrons• Energy levels around
nucleus
Negative electrons• Atoms are neutrally
charged
Protons (+) = Electrons (-)
NUMBERS
• Atomic number: number of protons
Protons identify the element
• Mass number: number of protons + neutrons
• Neutrons = mass number – protons
P=6N=7
1st energy level = 22nd energy level = 83rd energy level = 18
Protons=ElectronsP + N = Mass #Mass # - P = N
ISOTOPES
• Same number of protons but different number of neutrons and different masses
• Atom: smallest unit of all matter
• Element: made of only 1 kind of atom
VOCABULARY TERMS
• Molecule: 2 or more atoms chemical combined; smallest particle of a compound
• Compound: 2 or more different atoms chemically compound
BONDING
• Depends on arrangement and how many valence (outer) electrons
• Ionic
Transfer of electrons between atoms
Metals tend to lose (positive ions) and nonmetals tend to gain (negative ions)
BONDING
• Covalent
Sharing of electrons between nonmetals (like atoms)
Nonpolar covalent (equal sharing)
Polar covalent (unequal sharing)
WATER
• Polar molecule• Oxygen: greater
attraction for electrons
• Slightly negative oxygen end
• Slightly positive hydrogen end
HYDROGEN BONDS
• Weaker bonds between water molecules
• Responsible for ability to form 4 hydrogen bond
• Cohesion: attraction between same substance (water)
PROPERTIES OF WATER DUE TO COVALENT BOND• Surface tension:
adhesion (different molecules) and cohesion (like molecules)
• Capillary action: movement of water up roots
• http://www.youtube.com/watch?feature=player_detailpage&v=VHnFMPxteGo
CHARACTERISTICS OF WATER
• High specific heat: water warms and cools very slowly
Biological importance: aquatic organisms are able to adjust slowly to the changing environment.
• Freezing: bonds expand and ice becomes less dense and will float
Biological importance: top frozen layer helps insulate lake/pond
FREEZING
• Ice is less dense as a solid than as a liquid (ice floats)
• Frozen water forms a crystal-like lattice with molecules set at fixed distances.
High Heat of Vaporization
• Amount of energy to convert 1g or a substance from a liquid to a gas
• Hydrogen bonds must be broken
so water
evaporates and
removes heat
Solutions & Suspensions
• Many things dissolve in water--the Universal Solvent
• Usually part of a mixture.
• Two types of mixtures:
Solutions
Suspensions
Defn: material composed of 2 or more substances physically combined
SOLUTIONS
• Evenly distributed substances
• Solute: material dissolved
• Solvent: dissolving material
• Solute: salt
Solvent: water
Suspensions
• Solute breaks up into pieces that will not settle out.
• Blood
Plasma (liquid part)
Dissolved compounds (solute)
ACIDS, BASES, pH
• pH: measures concentration of H+
• 1-14 scale• Below 7: acidic• 7: neutral• Above 7: basic
REVIEW
• Which bond is formed by the transfer of electrons between atoms?
(Ionic)• Which bond is the weakest and forms
between water molecules? (hydrogen)• Acids form ____ ions in solution. (H+ --hydrogen ions)• What is the solute? (material dissolved in solution)
WATER CHARACTERISTICS
• http://www.youtube.com/watch?feature=player_detailpage&v=0eNSnj4ZfZ8