DR. K REVIEWS . . . : DR. K REVIEWS . . . PRESENTATION 2
BASIC CHEMISTRY jammasterk.com
MATTER & ELEMENTS : MATTER & ELEMENTS MATTER IS PHYSICAL STUFF
MATTER IS COMPOSED OF ELEMENTS.
ELEMENT = A SUBSTANCE THAT CANNOT BE BROKEN DOWN INTO SIMPLER SUBSTANCES
EACH ELEMENT IS REPRESENTED BY ATOMS
ATOM =
SMALLEST UNIT OF AN ELEMENT
RETAINS THE PROPERTIES OF THAT ELEMENT
ATOMIC STRUCTURE : ATOMIC STRUCTURE ALL ATOMS ARE COMPOSED OF THREE BASIC TYPES OF SUBATOMIC PARTICLES
PROTONS
NEUTRONS
ELECTRONS
PROTONS AND NEUTRONS ARE CONTAINED IN THE NUCLEUS
ELECTRONS ARE FOUND OUTSIDE OF THE NUCLEUS
THERE ARE TWO MODELS OF ATOMIC STRUCTURE
THE BOHR MODEL
THE ELECTRON CLOUD MODEL
FOCUS ON PROTONS : FOCUS ON PROTONS PROTONS HAVE A POSITIVE CHARGE
PROTONS HAVE A MASS OF ONE DALTON
PROTONS ARE LOCATED IN THE NUCLEUS
FOCUS ON NEUTRONS : FOCUS ON NEUTRONS NEUTRONS HAVE A NEUTRAL CHARGE
NEUTRONS HAVE AND MASS OF 1 DALTON
NEUTRONS ARE LOCATED IN THE NUCLEUS
RULE OF THUMB: THE NUMBER OF NEUTRONS EQUALS THE NUMBER OF PROTONS (EXCEPTIONS)
FOCUS ON ELECTRONS : FOCUS ON ELECTRONS ELECTRONS HAVE A NEGATIVE CHARGE
ELECTRONS HAVE A NEGLIGIBLE MASS
ELECTRONS ARE LOCATED OUTSIDE OF THE NUCLEUS
ORBITALS OR ELECTRON SHELLS BOHR MODEL)
ELECTRON CLOUD (ELECTRON CLOUD MODEL)
RULE OF THUMB: THE NUMBER OF ELECTRONS EQUALS THE NUMBER OF PROTONS(EXCEPTIONS)
CHARACTERISTICS OF ATOMS : CHARACTERISTICS OF ATOMS NAME = ELEMENT NAME
CHEMICAL SYMBOL
ATOMIC NUMBER = NUMBER OF PROTONS
ATOMIC MASS = NUMBER OF PROTONS + NUMBER OF NEUTRONS
ISOTOPES : ISOTOPES RULE OF THUMB: THE NUMBER OF PROTONS EQUALS THE NUMBER OF NEUTRONS
EXCEPTION = ISOTOPE
ISOTOPE = ATOM WITH ONE OR MORE EXTRA NEUTRONS
EXAMPLE: CARBON
CARBON 12
CARBON 13
CARBON-14
MORE FOCUS ON ELECTRONS : MORE FOCUS ON ELECTRONS ELECTRONS REPRESENT POTENTIAL ENERGY
POTENTIAL ENERGY = STORED ENERGY
THE AMOUNT OF STORED ENERGY IS RELATED TO THE ELECTRON SHELL POSITION
INNERMOST SHELLS = LOWER ENERGY
OUTER SHELLS = HIGHER ENERGY
ELECTRONS CAN BE USED AS VEHICLES FOR MOVING ENERGY
ELECTRON SHELLS AND ELECTRON POSITION : ELECTRON SHELLS AND ELECTRON POSITION THE INNERMOST ELECTRON SHELL…
S ORBITAL
HOLDS 2 ELECTRONS
OUTER ELECTRON SHELLS…
P ORBITALS
HOLDS 8 ELECTRONS
ELECTRONS ARE ADDED FROM THE INSIDE OUT
THE OUTERMOST ELECTRONS ARE CALLED VALENCE ELECTRONS
THE OUTERMOST SHELL IS CALLED THE VALENCE SHELL
THE VALENCE SHELL & ATOMIC STABILITY : THE VALENCE SHELL & ATOMIC STABILITY ATOMIC STABILITY = A FULL VALENCE SHELL
2 ELECTRONS = S ORBITAL
8 ELECTRONS = P ORBITALS
EXAMPLES OF STABLE ATOMS = THE NOBLE GASES (UNREACTIVE ATOMS)
ARGON
NEON
KRYPTON
RADON
GAINING AND LOSING ELECTRONS : GAINING AND LOSING ELECTRONS OXIDATION AND REDUCTION
OXIDATION = THE LOSS OF ONE OR MORE OF ELECTRONS
FROM AN ATOM
FROM A MOLECULE
AN ATOM/MOLECULE THAT HAS LOST AN ELECTRON IS SAID TO BE OXIDIZED
REDUCTION = THE GAIN OF ONE OR MORE OF ELECTRONS
FROM AN ATOM
FROM A MOLECULE
AN ATOM/MOLECULE THAT HAS GAINED AN ELECTRON IS SAID TO BE REDUCED
IONS : IONS OXIDATION/REDUCTION WILL CAUSE A CHANGE IN ATOMIC CHARGE
A CHARGED ATOM IS CALLED AN ION
OXIDATION = LOSS OF AN ELECTRON = LOSS OF A NEGATIVE CHARGE = A POSITIVELY CHARGED ATOM = A CATION
REDUCTION = GAIN AN ELECTRON = GAIN A NEGATIVE CHARGE = A NEGATIVELY CHARGED ATOM= AN ANION
ATOMIC BONDING: COVALENT BONDING : ATOMIC BONDING: COVALENT BONDING ATOMIC BONDING INVOLVES VALENCE ELECTRONS
COVALENT BONDING =
ELECTRONS SHARED
SINGLE BOND = 1 PAIR OF ELECTRONS SHARED
DOUBLE BOND =2 PAIR OF ELECTRONS SHARED
POLAR COVALENT BOND = UNEQUAL SHARING OF ELECTRONS = CHARGE DISTRIBUTION
NONPOLAR COVALENT BOND = EQUAL SHARING OF ELECTRONS = NO CHARGE DISTRIBUTION
ATOMIC BONDING: IONIC BONDING : ATOMIC BONDING: IONIC BONDING IONIC BONDING =
ELECTRONS LOST BY ONE ATOM
ELECTRONS GAINED BY ONE ATOM
AN IONIC BOND CREATES IONS
CATION
ANION
ATOMIC BONDING: HYDROGEN BONDING : ATOMIC BONDING: HYDROGEN BONDING HYDROGEN BOND = A WEAK ELECTROMAGNETIC ATTRACTION BETWEEN OPPOSITE CHARGES
HYDROGEN BONDS FORM BETWEEN WATER MOLECULES
HYDROGEN ATOMS WITH POSITIVE CHARGE
OXYGEN ATOM WITH NEGATIVE CHARGE
HYDROGEN BONDS CAN FORM BETWEEN CHARGED PORTIONS OF OTHER MOLECULES
NOTE: A HYDROGEN BOND DOES NOT INVOLVE ELECTRONS
WATER: MOLECULAR STRUCTURE : WATER: MOLECULAR STRUCTURE WATER IS A MOLECULE WITH POLAR COVALENT BONDS BETWEEN THE OXYGEN AND THE HYDROGENS
WATER IS A POLAR MOLECULE… WATER IS A POLAR COMPOUND
A SINGLE WATER MOLECULE CAN FORM A TOTAL OF FOUR HYDROGEN BONDS
WATER: PROPERTIES I : WATER: PROPERTIES I WATER IS A POLAR SOLVENT = IT DISSOLVES POLAR SUBSTANCES, AND IONIC COMPOUNDS
BIOLOGICAL REACTIONS OCCUR IN AN AQUEOUS SOLUTION IN ORGANISMS AND THEIR CELLS
WATER: PROPERTIES II : WATER: PROPERTIES II WATER HAS A HIGH SPECIFIC HEAT = WATER STORES HEAT
BODIES OF WATER TEND TO RESIST CHANGES IN TEMPERATURE
BODIES OF WATER CAN MODERATE CLIMATE
WATER: PROPERTIES III : WATER: PROPERTIES III WATER HAS A HIGH HEAT OF VAPORIZATION = EVAPORATION IS ENERGETICALLY EXPENSIVE
EVAPORATIVE COOLING IS A MEANS OF THERMAL HOMEOSTASIS
WATER: PROPERTIES IV : WATER: PROPERTIES IV WATER DEMONSTRATES COHESION = WATER MOLECULES TEND TO STICK TO ONE ANOTHER
EXAMPLE 1: WATER RISES THROUGH XYLEM TISSUE IN TREES.
EXAMPLE 2: SURFACE TENSION
WATER: PROPERTIES V : WATER: PROPERTIES V WATER DEMONSTRATES ADHESION = WATER MOLECULES TEND TO STICK TO OTHER THINGS
WATER: PROPERTIES VI : WATER: PROPERTIES VI THE SOLID FORM OF WATER IS NOT THE MOST DENSE FORM OF WATER
ICE IS A CRYSTALLINE STRUCTURE
THE MAXIMUM DENSITY OF LIQUID WATER IS AT 4° C
WATER: PROPERTIES VII : WATER: PROPERTIES VII WATER CAN DISSOCIATE (IONIZE) = AT ANY GIVEN MOMENT, A MINORITY OF WATER MOLECULES WILL DISSOCIATE INTO
HYDROGEN IONS (H+)
HYDROXIDE IONS (OH-)
THE DISSOCIATION OF WATER IS THE BASIS FOR PH
pH : pH PH IS A MEASURE OF THE HYDROGEN ION CONCENTRATION IN THE SOLUTION
PH IS INVERSELY PROPORTIONAL TO THE HYDROGEN ION CONCENTRATION
PH RANGE IS FROM 1TO 14
THE PH OF PURE WATER IS 7
A PH RANGE OF 1-7 IS ACID
A PH RANGE OF 7-14 IS BASIC
ACIDS : ACIDS AN ACID IS A PROTON DONOR
AN ACID HAS HYDROGENS AVAILABLE
PH RANGE 1-7
EXAMPLE: HCL
BASES : BASES A BASE IS A PROTON ACCEPTOR
BASES HAVE HYDROXIDES (OH GROUPS)
PH RANGE 7-14
EXAMPLE: NaOH
ACID/BASE REACTIONS : ACID/BASE REACTIONS ACIDS AND BASES REACT TO FORM SALTS
A SALT IS AN IONICALLY BONDED COMPOUND
SALTS ARE SOMETIMES CALLED ELECTROLYTES
EXAMPLE:
HCl + NaOH NaCl + H2O
BUFFERS : BUFFERS BUFFERS ARE SUBSTANCES THAT RESIST CHANGES IN PH (HOMEOSTASIS)
BUFFERS FUNCTION AS PROTON RESERVOIRS
EXAMPLE: BICARBONATE BUFFERING SYSTEM
CO2 + H2O H2CO3 H+ + HCO3-
carbon dioxide+ carbonic hydrogen ion+
Water acid bicarbonate ion