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BIOLOGIC CHEMISTRY
Chapter 2 – Part 1The Chemistry of Life
CP BiologyPaul VI Catholic High School
BIOLOGIC CHEMISTRYNATURE OF MATTER:
ATOMS: “Basic unit of matter”
An atom is the smallest portion of a substance that still retains the unique properties of that substance.
• PROTONS: Positive charge (1.009 DALTONS)
• NEUTRONS: No Charge (1.007 DALTONS)
• ELECTRONS: Negative charge (1/1840 DALTONS)
1 DALTON = 1.66054X10-24 kilograms
(1/12 the mass of Carbon)
BIOLOGIC CHEMISTRY
NUCLEUS:• CENTER OF ATOM• CONTAINS PROTONS AND NEUTRONS
ORBITALS:• CONTAIN ELECTRONS
In a neutral atom, the number of protons equals the number of electrons
BIOLOGIC CHEMISTRYELECTRON CONFIGURATION:
ENERGY LEVELS CONTAIN:2, 8, 18, 32 electrons
ENERGY SUBLEVELS:s level: 2 electronsp level: 6 electronsd level: 10 electronsf level: 14 electrons
Periodic chart (including Bohr models)
BIOLOGIC CHEMISTRY
• Periodic means repeating in a pattern
The Periodic Table of Elements
…is the arrangement of elements according to repeating changes in properties .
• The boxes for the elements are arranged in order of their atomic numbers.
• Vertical columns are groups or families.• Horizontal rows are called periods.
BIOLOGIC CHEMISTRY
BIOLOGIC CHEMISTRY
ELEMENT:Atomic Number = protons Atomic Mass = protons + neutrons
ISOTOPES:Vary in number neutronsSame Chemical PropertiesSome Radioactive
BIOLOGIC CHEMISTRY
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition CHAPTER 2 Atoms and Molecules: The Chemical Basis of Life
Carbon Isotopes
BIOLOGIC CHEMISTRY
RADIOACTIVE DECAY:α wavesβ wavesγ waves
CARBON DATING:“Half-Life” 5600 years
BIOLOGIC CHEMISTRYCHEMICAL COMPOUNDS:
Substances formed by the combination of two or more different elements in a fixed ratio. They are “pure” substances.
MOLECULE:
Smallest unit of covalently bonded compound.
BIOLOGIC CHEMISTRY A chemical formula uses the symbols for the elements in the compound.
Na + Cl → NaCl
Some formulas include subscripts to show ratios of more than one atom.
2 H + 1 O → H20
BIOLOGIC CHEMISTRY
CHEMICAL FORMULA: Shorthand expression describing chemical composition
SIMPLEST FORMULA CaN2O6
(Empirical Formula)
MOLECULAR FORMULA Ca(NO3)2
STRUCTURAL FORMULA
BIOLOGIC CHEMISTRY
BIOLOGIC CHEMISTRY
BIOLOGIC CHEMISTRYCHEMICAL BONDS:
Bond energy is the energy necessary to break a chemical bond.
• COVALENT BOND • holds molecule together by sharing electrons
• IONIC BOND • holds molecule together by transfer of electrons
• VAN DER WAALS FORCES • temporary dipole attraction between molecules • Results in higher boiling points
• HYDROGEN BONDS• Attraction between molecules with partially positive
and partially negative areas
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition CHAPTER 2 Atoms and Molecules: The Chemical Basis of Life
Covalent bonds
BIOLOGIC CHEMISTRY
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition CHAPTER 2 Atoms and Molecules: The Chemical Basis of Life
Ionic bonding
BIOLOGIC CHEMISTRY
Hydrogen
Bonding
BIOLOGIC CHEMISTRY
• Hydrogen bonds- partially positive charged “H”end of a molecule is attracted to partially negative charged end of another molecule
BIOLOGIC CHEMISTRYCHEMISTRY OF WATER:
ATOMIC STRUCTURE:10 Protons10 ElectronsCovalent BondPolar Structure
BIOLOGIC CHEMISTRY
PROPERTIES OF WATER:1.COHESION: Attraction between molecules of the same substance.
2. ADHESION: Attraction between different substances.
3. HIGH SPECIFIC HEAT: 1Cal./gm/oC
4. HIGH HEAT OF VAPORIZATION: (Heat energy required to change 1 gm. liquid water to gas.)
BIOLOGIC CHEMISTRY
SOLUTION: Homogeneous (uniform) mixture of a liquid.
solvent- dissolving agentsolute- substance that is dissolvedaqueous solution- solution with water as solvent
MIXTURE: Substance composed of two or more elements or compounds that are together BUT are not chemically combined.
SUSPENSION: Composed of nonpolar molecules in water. Water acts to exclude them.
BIOLOGIC CHEMISTRY
BIOLOGIC CHEMISTRYCOLLOIDS: Heterogeneous mixtures containing particles intermediate in size between suspensions and solutions.
TYNDALL EFFECT – light scattering effect in colloids
BIOLOGIC CHEMISTRYACID / BASE / pH
pH: (“pouvoir hydrogene”)
Calculated from the spontaneous dissociation of water
Negative logarithm of the [H+]
Each change in a pH unit is a tenfold change in concentration
BIOLOGIC CHEMISTRY
ACIDS:
Any substance that dissociates in water to increase the H+ concentration
BASES:
Any substance that dissociates to decrease the H+ concentration.
BIOLOGIC CHEMISTRY
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition CHAPTER 2 Atoms and Molecules: The Chemical Basis of Life
pH valuesof commonsolutions
BIOLOGIC CHEMISTRY
BIOLOGIC CHEMISTRY
BUFFERS:Substance that acts as reservoir for H+.
• Carbonic Acid Buffer System
BIOLOGIC CHEMISTRY