March 2015
March 18-20, 2015
Molecular
compound
Compound
made up of 2 or more nonmetals
Structural
formula
Chemical
formula that show the arrangement, type and number of the atoms in a compound
Shared
electron pairs
Valence
electrons that participate in a covalent bond.
Unshared
electron pairs
Valence
electrons that do not participate in a
covalent bond.
Covalent
Bond
A chemical
bond that results from the sharing of valence electrons
A molecule
is formed when two or more atoms bond covalently
Single
Covalent Bond
A bond in
which two electrons are shared by two atoms
Double
Covalent Bond
A bond in
which four electrons are shared by two atoms
Triple
Covalent Bond
A bond in
which six electrons are shared by two atoms
coordinate
covalent bond
covalent
bond in which both shared electrons are donated by the same atom
Resonance
when two or
more electron dot structures can be written for the same compound
Polarity
The state
of having two opposite poles. One positive (or slightly positive) and one
negative (or slightly negative.
Polar Bond
A covalent bond in which the
electrons are not shared equally.
This creates a bond in which one side is more positive and the other side is
more negative.
Dipole
Having two
poles
Polar Molecule
A molecule that has a
positive and negative end due to its' polar bonds and it's molecular geometry.
Shapes
Linear
180 2 or
3 atoms
Bent 104.5 3
atoms
Trigonal
planar 120 4
atoms
Trigonal
pyramidal
107.3 4 atoms
Tetrahedral
109.5 5 atoms
Resonance
when two or
more electron dot structures can be written for the same compound
.
Valance electrons
The
electrons in the highest occupied energy level of the atom
The number of valance
electrons determines the chemical properties of the element
Electron dot (Lewis Electron Dot) Structure
An elements
atomic symbol surrounded by the number of valance electrons in the element
Octet Rule
Atoms in
compounds tend to have the electron configuration of a noble gas (8 outermost
electrons)
Cation
An atom that
loses valence electrons to satisfy the octet and acquires a positive charge
Anion
An atom that
gains valence electrons to satisfy the octet and acquires a negative charge
Ionic Compounds
A compound composed of positive and negative
ions
Ionic bond
The electrostatic attraction that binds oppositely charged ions together
Coordination number
The number
of oppositely charged ions that surround an ion in a crystal
Properties of ionic compounds
- high melting point
-conducts electricity when dissolved in water or melted
-crystal structure
-hard
-brittle
Metallic bonds
The attraction of free-floating valence electrons for positively charged
metal ions (cations).
Properties of metals
- malleable
-conduct heat and electricity
-high melting points
-strong
Periodic Trends
Atomic Radius
The term used to describe the size of the atom.
The atomic radius of an atom decreases as you move left to right across a
period and increases as you
move from top to bottom down a group.
Ion
An atom that acquires a charge by losing or gaining electrons.
Ionization energy
The energy needed to remove an electron from an atom.
The ionization energy of an atom increases as you move left to right across a
period and decreases as you
move top to bottom down a group.
Electronegativity
An atoms ability to attract electrons while in a chemical bond.
Electronegativity increases left to right across a period and decreases top to
bottom down a group.
All three periodic trends can be explained using the same reasoning
As you move across a period from left to right each atom has one
proton and one electron more than the previous atom. The protons are
added to the nucleus increasing the nuclear charge. The electrons are
added to the same energy level
as you move across a group. All the
electrons in the period(energy level) have the same distance from the nucleus.
As you move down a group from top to bottom you are adding
energy levels with each step down. The nuclear distance is increasing with each step down a group.
*** Nuclear attraction increases left to right across a period and decrease top
to bottom down a group due to the distance
between the nucleus (+) and the outermost electrons(-) and the addition of
protons and electrons.
Shielding effect
Inner (core) electrons shield the outermost electrons from the nuclear attraction.
march 2
ATOMIC STRUCTURE REVISITED
99% OF ALL CHEMISTRY CAN BE EXPLAINED BY THE ARRANGEMENT OF THE ELECTRONS IN THE ATOMS, IONS OR MOLECULES
Neils Bohr electrons have energy (E)
The Bohr Atom
a) There is a nucleus (this was Rutherford's discovery).
b) The electrons move about the nucleus in "orbits" also called energy levels or shells.
c) When an electron moves from one energy level to another, the energy lost or gained is done so ONLY in very specific amounts of energy. These specific amounts of energy are called quanta. The energy is said to be quantized.
d) Specific spectra (light energy) are absorbed or released when an electron moves from one energy level to another.
e) Each element absorbs or releases spectra that are specific for that element and therefore can identify the element.
MAX PLANCK
MATTER CAN LOSE OR GAIN ENERGY IN SMALL, SPECIFIC AMOUNTS CALLED QUANTA
QUANTUM
THE AMOUNT OF ENERGY NEEDED TO MOVE AN ELECTRON FROM ITS PRESENT ENERGY LEVEL TO THE NEXT HIGHER ENERGY LEVEL
Eq=hγ
Eq=ENERGY OF A QUANTUM H= PLANCKS CONSTANT γ= FREQUENCY
LIGHT
ENERGY THAT TRAVELS IN WAVES.
WAVES
A DISTURBANCE THAT CARRIES ENERGY
ELECTROMAGNETIC RADIATION
waves that travel at the speed of light (3.0 x 1023 m/sec) and can travel in any medium including a vacuum.
WAVELENGTH
THE HORIZONTAL DISTANCE BETWEEN TWO IDENTICAL POINTS ON TWO ADJACENT WAVES
FREQUENCY
the number of waves that pass by per second. Frequency is usually measured in Hertz (cycles/sec)
AMPLITUDE
Amplitude is the distance from the rest position to the crest position which is half the vertical distance from a trough to a crest
SPECTROSCOPE
INSTRUMENT USED TO MEASURE THE WAVELENGTH OF VISIBLE LIGHT
ELECTRON CONFIGFURATION
THE WAYS IN WHICH THE ELECTRONS ARE ARRANGED AROUND THE NUCLEUS
PHOTON
A QUANTUM OF LIGHT ENERGY
RULES FOR ELECTRON CONFIGURATION
1) AUFBAU PRINCIPLE: ELECTRONS WILL ALWAYS OCCUPY THE LOWEST ENERGY ORBITALS AVAILABLE.
2) PAULI EXCLUSION PRINCIPLE: A MAXIMUM OF 2 ELECTRONS (WITH OPPOSITE SPINS) CAN OCCUPY AN ORBITAL.
3) HUND'S RULE: FOR EQUAL ENERGY ORBITALS, ELECTRONS WILL OCCUPY EACH ORBITAL BEFORE PAIRING UP
NOBEL GAS (SHORTCUT) ELECTRON CONFIGURATION IS DONE BY FIRST WRITING THE PREVIOUS NOBEL GAS IN PARANTHESES, FOLLOWED BY THE REMAINING ELCTRON CONFIGURATION.
VALENCE ELECTRONS:
THE ELECTRONS IN AN ATOMS OUTERMOST ORBITALS. VALENCE ELECTRONS DETERMINE THE ELEMENTS CHEMICAL PROPERTIES.
LIGHT
ENERGY THAT TRAVELS IN WAVES.
ALSO CALLED ELECTROMAGNETIC RADIATION
ELECTROMAGNETIC RADIATION
WAVES THAT DO NOT NEED A MEDIUM TO TRAVEL AND TRAVEL AT THE SPEED OF LIGHT (3.0 X 10^23 METERS PER SECOND) IN A VACUUM.
RADIATION
THE EMISSION OF ENERGY AS ELECTROMAGNETIC WAVES
WAVES
A DISTURBANCE THAT CARRIES ENERGY
WAVELENGTH
THE DISTANCE BETWEEN TWO IDENTICAL POINTS ON TWO ADJACENT WAVES
FREQUENCY
THE NUMBER OF WAVES THAT PASS THROUGH A SPECIFIC AREA PER SECOND
SPECTROSCOPE
INSTRUMENT USED TO MEASURE THE WAVELENGTH OF VISIBLE LIGHT
ELECTROMAGNETIC SPECTRUM
THE RANGE OF ALL POSSIBLE FREQUENCIES OF ELECTROMAGNETIC RADIATION
ENERGY LEVELS
A REGION AROUND THE NUCLEUS OF THE ATOM WHERE THE ELECTRON IS MOVING.
GROUND STATE
THE LOWEST ENERGY LEVEL OCCUPIED BY AN ELECTRON. THE MOST STABLE STATE OF THE ATOM.
EXCITED STATE
AN ENERGY LEVEL HIGHER THAN THE GROUND STATE
ATOMIC EMISSION
FREQUENCIES OF ELECTROMAGNETIC RADIATION EMITTED DUE TO AN ATOM'S TRANSITION FROM A HIGHER ENERGY LEVEL TO A LOWER ENERGY LEVEL
March 24, 2014
Valence
electrons that participate in a covalent bond.
March 24
Students went over the test
Intramolecular forces are the attractive forces that hold atoms or ions together within ionic compounds, molecules or metals. Examples are covalent bonds, ionic bonds and metallic bonds.
Intermolecular forces are the attractive forces that bond molecules to other identical molecules.
Intramolecular forces are much stronger than intermolecular forces
Intermolecular forces
Van der Walls Forces
1) dispersion forces-weakest of all intermolecule forces.
Caused by the motion of electrons
animation
2) dipole-dipole forces- attraction of a polar molecule to another polar molecule
animation
Hydrogen bonds
a hydrogen bonded to a very electronegative atom bonds weakly to an unshared electron pair on a similar molecule. Hydrogen bonds are the strongest of the intermolecular forces
animation
March 14, 2014
Polarity
The state of having two opposite poles. One positive (or slightly positive) and one negative (or slightly negative.
Polar Bond
A covalent bond in which the
electrons are not shared equally.
This creates a bond in which one side is more positive and the other side is more negative.
Dipole
Having two poles
Polar Molecule
A molecule that has a
positive and negative end due to its' polar bonds and it's molecular geometry.
March 12, 2014
Valence
electrons that participate in a covalent bond.
Shapes
Linear 180 2 or 3 atoms
Bent 104.5 3 atoms
Trigonal
planar 120 4 atoms
Trigonal
pyramidal 107.3 4 atoms
Tetrahedral 109.5 5 atoms
March 10, 2014
coordinate covalent bond
covalent bond in which both shared electrons are donated by the same atom
Resonance
when two or more electron dot structures can be written for the same compound
March 4, 2014
Coordination number
the number of ions of opposite charge that surround an ion in a crystal.
Metallic Bond
the attraction of the free flowing valence electrons of the metal for the metal cations.
Molecular (covalent) compound
compound made up of two or more nonmetals that are covalently bonded togeather into a molecule.
Covalent Bond
A chemical bond that results from the sharing of valence electrons
A molecule is formed when two or more atoms bond covalently
Single Covalent Bond
A bond in which two electrons are shared by two atoms
Double Covalent Bond
A bond in which four electrons are shared by two atoms
Triple Covalent Bond
A bond in which six electrons are shared by two atoms
.
March 22, 2013
Honors
animation of dissolving
Heat of Solution
the energy change that takes place during the formation of a solution
c
Unsaturated solution
a solution that contains less dissolved solute for a given temperature and pressure than can be dissolved.
Saturated solution
a solution that contains the maximum amount of dissolved solute for a given temperature and pressure.
Supersaturated solution
a solution that contains more than the maximum amount of dissolved solute for a given temperature and pressure.
The solubility of a gas decreases with increased temperature.
Henry's Law
at a given temperature, the solubility(s) of a gas in a liquid is directly proportional to the pressure(P) above the liquid.
S1 = S2
P1 P2
Colligative properties
physical properties of solutions that depend only on the number of dissolved particles.
Vapor pressure lowering
adding a solute to a solvent lowers the solvents vapor pressure.
Boiling point elevation
adding a solute to a solvent will raise the boiling point
Freezing point depression
adding a solute to a solvent will decrease the freezing point
March 13, 2013
Honors
Students took the second test of the marking period today.
Blocks were only 63 minutes due to todays early dismissal.
March 11, 2013
Honors
Students began class by reviewing for the upcoming test the next time we meet, wednesday.
The class then worked on stochiometry that included the gas laws and mostly Avagadros principle.
We then began a lab that proved molar volume at STP of 22.4 liters.
gas_laws_mixed_2_ws.pdf | |
File Size: | 62 kb |
File Type: |