Historical development of the current
atomic theory
• Models:
• Ruterford: gold foil experiment, predicted the presence of a
nucleus because positive particles “shot” at the sheet of gold foil
were deflected.
• Dalton- said atoms
• are indivisible, combine in whole # ratios, of same element are the
same
• Thompson – plum pudding model discovered the charge to mass
ratio of an electron
• Milikan- oil drop experiment. Discovered the charge of an
electron.
• Bohr model – atoms are quantized. Electrons exist at certain
energy levels as evidenced by bright line spectrums that each atom
exhibits when it glows.
Waves- Electromagnetic Theory
• Frequency and wavelength are inversely
related
• Energy and frequency are directly related
• Energy and wavelength are inversely related
Atomic Structure
• Atom contains: Protons & neutrons in
nucleus; electrons in electron clouds
(probability clouds) at certain energy levels
Subatomic
Particle
Charge
Relative mass
Proton (p+)
+1
1 amu, 1.67 x 10-24g
Neutron (n0)
0
1 amu, 1.67 x 10-24g
Electron (e-)
-1
1/2000 amu, insignificant
Atomic Structure
• Number of protons = atomic number
• Number of electrons = same as protons unless it
is an ion then cations (+) lose e- ; anions (-) gain
e• Number of neutrons = mass number – atomic
number
• Atomic mass is a weighted average determined
by the relative abundance of each isotope. So
the average is closest to the most abundant
isotope.
Isotopes
• Isotope designations: 235
U-235
92 U
• Isotopes: same element , same atomic
number, different atomic masses
Symbols of Chemistry
• State symbols: (s) – solid, or a precipitate(
products of DR); (l) – liquid; (g)- gas; (aq)aqueous (dissolved in water)
• Element Symbols from the PTOE
PTOE
• Metals
– High Melting points
– Lusterous
– Solid at room temp except Hg
– Conductive
– Malleable and ductile
– Most metallic element – bottom left.
– Hydrogen is not a metal
PTOE
• nonmetals
– Low melting points – liquid or gas at room temp
– Dull
– Non-conductive
– Brittle
– Most non-metallic element top left
Periodic Trends
Increase as go across a period and Decrease as go down a
group
– Electron Affinity – attraction to electrons
– Ionization energy- energy needed to remove an
electron
– Electronegativity – attraction to a shared pair of
electrons
Decrease across, increase down
– Metallic property
– Atomic Radius- size of atom
Language of Chemistry
• Covalent/Molecular Cmpds--- name: prefixes and end last element
in –ide Formulas: prefixes!!!!!
• Ionic (binary)– Naming: name ions ; Positive ion(M) –same as
element name ; Negative ion (Nm)end in –ide
Formulas: crisscross charges
• Ionic (Ternary) Naming: name ions, do not change name if ion is
polyatomic
Formulas: Crisscross charges
• Know: hydrochloric acid (HCl) nitric acid (HNO3); sulfuric acid
(H2SO4), acetic acid (HC2H3O2 or CH3COOH)
Physical Properties
• All substance have their own Boiling point,
melting point and density. Use the reference
tables to identify substances.
• Density= mass/volume; D=m/v
Physical Properties
• Solubility rules
• For DR reactions….
insoluble product
precipitates
Bonding
• Ions form so that an atom will have 8 valence
electrons.
• Ions from the periodic table: +1, +2,+3, +/-4, 3,-2,-1
• Cations (positive) form from the loss of
electrons
• Anions (negative form from the gain of
eletrons)
Ionic Bonds
• Ionic bonds form from the electrostatic
attraction between oppositely charged
particles
• Compounds are ionic by rule of thumb if it has
a metal in it or if the EN > 1.7
• Ionic compounds have predictable properties:
high MP, high BP, brittle, and high electrical
conductivity either in molten state or in
aqueous solution.
Covalent Bonds
• Form when atoms share electrons –(no ions)
• Have predictable properties: low MP, low BP,
poor electrical conductivity, polar nature, etc.
• Non-metals bonded to nonmetals or when EN <
1.7.
• Diatomic elements are non-polar covalent bonds
with single (F2), double (O2), or triple (N2) bonds.
• Single bonds are have less bond energy and
longer bond lengths than double or triple bonds.
(they are easier to break)
Lewis Dot Structures: Covalent
•
•
•
•
Determine number of Valence e_
Choose central atom
Arrange ligands around the central atom
Arrange dots’ in pairs around central atom so
that every atom has 8 (until you run out
Metallic Bonds
• Occur between metal atoms of the same
metal or alloys
• Have predictable properties: high MP, high BP,
high conductivity, malleability, ductility, and
luster.
Molecular Polarity
• Bonds are polar if the EN > .4 Molecules are
polar if there is at least one lone pair on the
central atom and bonds are polar
• Describe intermolecular forces for molecular
compounds. Dispersion- Non-polar molecules,
Dipole-Dipole – polar molecules, Hydrogen bondH-N, H-F, H-O –special case
• “like dissolves like”—polar molecules dissolve
polar molecules, non-polar molecules dissolve
non-polar molecules.
Particles
Mass
Volume
(grams)
of a gas
(L)
Divide by molar volume
Divide by Avagadro’s #
22.4L
Divide by molar mass
Moles
Multiply by molar volume
Multiply by Avagadro’s
22.4L
#
Multiply by molar
mass
Particles
Mass
Volume
(grams)
of a gas
Empirical Formula
– Convert grams to moles
– Divide all moles by smallest moles
– round to nearest whole #, these are the subscripts
for the empirical formula
Molecular Formula: From Empirical
– (molar mass/ molar mass of empirical fomula)=
– Multiply the subscripts of the empirical formula by
the number you get.
% Composition
• (Mass of element/mass of cmpd)* 100
Types of Reactions
• Decomposition: 1 reactant
• Synthesis: 1 product
• Single Replacement: element + compound →
• Double replacement: cmpd + cmpd →
• Combustion of a hydrocarbon
CxHy + O2 → CO2 + H2O
Activity Series of Metals
• predicts whether a single replacement
reaction will take place. : free element must
be more active (higher up) than the element
that is already in compound.
Balancing Chemical Equations
• The number of atoms of each element must be the
same on eac side of the arrow. Do this by adding
coefficients not changing subscripts. Coefficients
must be added to the front of the cmpd.
• Mass of reactants = mass of products
Net Ionic Equations
For double replacement reactions
M+ + Nm- → MNm (ppt) criss cross charges
Indicators of Chemical Change
• Formation of a Precipitate: solubility rules
• Formation of a gas – Know the tests
Flaming splint: O2 burns, CO2 goes out, H2 pops
Lime water for CO2 == forms a ppt of CaCO3
• Color Change – Distinguish between color change as a
result of chemical reaction, and a change in color
intensity as a result of dilution.
• Change in Energy/Temperature change – Tie to
endothermic/exothermic reaction. Express H as (+)
for endothermic and (–) for exothermic
Ideal Gas Law
• Know characteristics of ideal gases
– Dimensionless points
– No attractive or repulsive forces
– KE proportional to temperature
– Have elastic collisions
Gas Formulas
• Know:
– 1 mole of any gas at STP=22.4 L
– Ideal gas equation (PV=nRT),
– Combined gas law (P1V1/T1 = P2V2/T2) and applications
holding one variable constant
– Avogadro’s Law (n/V=k), n1/V1 = n1/V2
– Dalton’s Law (Pt=P1+P2+P3 …)
– Vapor pressure of water as a function of temperature
(conceptually) ….vapor pressure increases at higher
temperatures
Conceptual Relationships: Gases
– Volume and pressure inversely proportional
– Volume and temperature – directly
– Volume and moles – directly
– Temperature and pressure- directly
Phase Changes
• Describe physical equilibrium: liquid waterwater vapor. Vapor pressure depends on
temperature and concentration of particles in
solution. (conceptual only – no calculations)
Heating and Cooling Curve
Temperature
Boiling
Melting
Heat added
Solution Problems
• M1V1 = M2V2
• Molarity = moles/liters
• Molality= moles/kg
Electrons- Energy
– an atom being “excited” above its ground state by
the addition of energy, resulting in the electron(s)
moving to a higher energy level.
– when the atom returns to its ground state, the
electron(s) releases that energy gained as
electromagnetic radiation (emissions spectrum).
• Energy released as photons
Law of Conservation of Energy
• Define and use the terms and/or symbols for:
enthalpy, entropy, specific heat capacity,
temperature, joule, endothermic reactions,
exothermic reactions, and catalyst.
Heat Calculations
• Complete calculations of:
– q=mCpT
– q = mHf
– q = mHv
– q lost=(-q gain)
Collision Theory
• molecules must collide in order to react, and
they must collide in the correct or appropriate
orientation and with sufficient energy to equal
or exceed the activation energy.
• reaction rate is proportional to number of
effective collisions.
Factors affecting Rxn Rate
• Increase temperature – increase speed of
molecules , increase # of collisions, increases rate
• Increase Concentration- less space to move
around results in more collisions, increase in rate
• Increased surface area, increases the # of places
to collide, therefore increases number of
collisions and the rate of reaction
• Catalyst lowers the activation energy, so that at a
given temperature, more molecules will have
energy equal to or greater than the activation
energy.
Entropy
• Increasing Entropy: solid  liquid  gas; Ionic
compounds  ions in solution
• entropy of the universe is increasing.
• measure of disorder.
Nuclear Chemistry
•
•
•
•
alpha ( 24He)
beta ( -10e)
gamma ()
penetrating ability of alpha, beta, and gamma
radiation
Nuclear Decay
– Decay as a random event, independent of other
energy influences
– Using symbols to represent simple balanced decay
equations
– Half-life (including simple calculations)
Uses of Nuclear Energy
• electricity
• Carbon-14 dating
• radioisotopes for medicine (tracers, ionizing
radiation, gamma sterilization, etc).
Fission and Fusion
Acids and Bases
– Acids (HX) – conductive, sting in cut, taste sour
– Bases (YOH)- conductive, slippery, taste bitter
• Arrhenius: acids – form hydronium, H3O+ and
bases form OH• Bronsted-Lowry acids- proton (H ion) donors;
bases- proton acceptors
• Strong does not mean concentration. 6M HCl
and 0.000006M HCl are both strong!!!
Indicators of Acids and Bases
•
•
•
•
Cabbage Juice
pH Paper
Litmus Paper
Phenothalein
Acid Base Calcuations
•
•
•
•
•
pH= -log (H+)
pOH= -log (OH-)
[H+] = antilog (-pH)
[OH-] = antilog (-pOH)
Titrations