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Chemical Basis of Life
Matter and Energy Matter- anything that occupies
space and has mass solid, liquid, gas
Mass-amount of matter a substance contains
Energy potential, kinetic light, heat, electrical, chemical
Basic Molecular Structure
Matter is comprised of elements, 92 of which occur naturally
Elements cannot be broken down into simpler substances
Identified by chemical symbolsOxygen, carbon, hydrogen, and
nitrogen make up 96% of body’s massCompounds are combination of two or
more elements
Compound & MixturesCompound
Combined chemically
Alters properties of individual components
Combined in exact proportions
Mixtures Combined physically
Retains properties of individual components
Proportions may vary
Types of mixturesSolutions - homogeneous mixture
Solute = dissolved substance Solvent = dissolving medium Concentrations
percentmolarity
Colloids (emulsions) - undergo sol-gel transformations
Suspensions - visible solutes that settle
What is an atom?
-smallest part of an element showing characteristics of that element
ATOMIC STRUCTUREa tomos = “not cut”Subunits
protons-located in the nucleus (+)
neutrons-located in the nucleus (0)
electrons-located in energy shells (-)
ATOMIC CHARACTERISTICSAtomic number - number of protons in
the nucleusMass number - number of protons
plus the number of neutronsAtomic weight (mass) - sum of the
number of protons,neutrons, and electrons
Number of protons equal the number of electrons
A complete atom is electrically neutral.
There is NO NET CHARGE!
Atomic Structure
Isotopes atoms with the same numbers of protons but have different numbers of neutrons
isotopes of an element react in the same manner chemically
Radioisotopes
Heavier isotopes are usually radioactive
Examples Carbon 14 Iodine -131 Radium - 226 Cobalt - 60
Electron shellselectrons orbit the nucleus of an
atom in shells/energy levels1st level - holds 2 e’s2nd level - up to 8 e’s3rd level - up to 18 number and arrangement of
electrons determine if an atom is chemically stable
CHEMICAL BONDS
A. Chemical bonds and electrons1. chemical bonds are a union between atoms caused by the sharing or exchange of electrons.2. the type of bond is determined by the arrangement of the electrons in orbit around the nucleus.
3. electrons are attracted to protons, but repelled by other electrons
4. electrons are arranged in orbits (orbitals) around the nucleus.
5. the electrons in the outermost orbital are called the valence electrons
6. valence electrons determine the chemical reactivity of an atom.
7. octet rule - atoms form bonds to have 8 electrons in their valence shell
CHEMICAL REACTIONS
Molecule - two or more atoms joined together ex. H-H; O=O
Compound - combination of atoms of two or more elements ex. CO2, H2O
Chemical EquationsReactants – left side of the equationProducts – right side of the equationMolecular Formula ExampleC6H12O6 + 6O2 ----- 6CO2 + 6H2O +
Energy
Patterns of Chemical Reactions
Synthesis = combinationDecomposition = breakdownDisplacement = reactants
exchangeOxidation Reduction
reactants lose or gain electronsoxidized - loses electronsreduced - gains electrons
Factors affecting reactions
TemperatureParticle SizeConcentrationCatalysts
CHEMICAL BONDSCovalent - involve the sharing of electrons between atoms
Ionic - bonding involving the loss or gain of electrons thus forming ions cation (+) anion (-)
Polar covalent - due to the unequal sharing of electrons between atoms
Hydrogen - type of covalent bond due to sharing of hydrogen electrons with neighboring hydrogen atoms
INORGANIC MOLECULES
ElectrolytesAcidsBasesSaltspHWater
ELECTROLYTES
Substances that ionize and dissociate in water and are capable of conducting an electrical current
Form charged particles (ions) in solution
Include acids, bases, and salts
ACIDS and BASES
Acid = substance that releases hydrogen ions (H+) in solution
Acts as a proton donorHCl ----> H+ + Cl-
Base = substance that dissociate in solution into hydroxide (OH-)
Acts as a proton acceptorNaOH ---> Na+ + OH-
pH - measure of acidity or alkalinity
pH 7.0 - neutralacidic - pH < 7.0basic - pH > 7.opH = - log [H+]
pH - range 0 - 14body fluids = 7.35-7.45 (7.40)
SALTSAcids and bases react with
other to form salts when mixed in equal concentrations
HCl + NaOH H2O + NaCl(salt)
WATER
Excellent solvent Polarity
Serves as a reactantImportant lubricantHigh heat of vaporizationHigh heat capacity
ORGANIC MOLECULES
Contain carbon atoms linked to each other in chains or rings
-carbohydrates, proteins, lipids, nucleic acids
CARBOHYDRATES
INCLUDE SUGARS AND STARCHES
PROVIDE MOST OF CELL’S ENERGY
CARBON - HYDROGEN - OXYGEN 1 : 2 : 1 RATIO
Monosaccharide simple sugars contain 3-7 carbon atoms ex. glucose, fructose, galactose
Disaccharides are formed when 2 monomers are hooked together by dehydration synthesis reactions
ex. sucrose (table sugar);lactose (milk sugar)
Carbohydrates/Polysaccharides
Complex sugarsVery large macromolecules
formed when long chains of simple sugars are hooked together
Glycogen - storage form of glucose in animals
Starch - storage form of glucose in plants
PROTEINSAmino acids are the building blocks of
proteinsContain carbon, hydrogen, oxygen,
nitrogen20 amino acids occur naturallyEssential for cell structures and
function enzymes, receptors, blood proteins, structural support
PROTEIN STRUCTURE
LEVELS
Primary structureSecondary structureTertiary structureQuaternary structure
H l
NH2 - C - COOH
l R
LIPIDS
Contain carbon, hydrogen, oxygen but not in a 1:2:1 ratio
Non-polar molecules that will not dissolve in water
Functions as energy source, structural support, integral part of membrane
TYPES OF LIPIDSTRIGLYCERIDES
fats/oils saturated fatty acids unsaturated fatty acids
Phospholipids important membrane component amphipathic
Steroids sex hormones cholesterol
Eicosanoids prostaglandins involved in blood clotting, inflammation, and contractions
NUCLEIC ACIDSDNA - deoxyribonucleic acidRNA - ribonucleic acidConsist of nucleotides
5 carbon sugar nitrogenous base - (adenine, thymine, cytosine, guanine, or uracil (only in RNA)).
phosphate group
ATPAdenosine TriphosphateMain energy carrier for
individual reaction needs