COMPETENCY GOAL 3

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COMPETENCY GOAL 3

• JACK BRITT HIGH SCHOOL

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The History of the Table

• Dobereiner (early 1800s) triads.
• Newlands (1865) atomic mass and octaves.
• Meyers and Mendeleev (1869) based on atomic
  mass and columns with similar properties.
• Moseley (1913) based on atomic number.

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The Periodic Law

• When elements are arranged in order of increasing
  atomic number, their physical and chemical
  properties show a periodic pattern.

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The Organization

• Groups or families and periods.
• Family names.
• Groups similar properties.
• Vertical columns vs. horizontal rows.
• Metals (transition inner transition),
  nonmetals, and semi-metals.

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Electron Configuration

• Electrons in the highest principle energy level
• Outermost electrons
• Valence electrons
• Elements in a group have similar properties
  because they have valence electrons in a similar
  configuration.
• Abbreviated electron configuration using the
  noble gas inner core.
• Four blocks (s, p, d, and f).

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Periodic TrendsA systematic variation in the
properties of elements going down a group or
across a period.

• Atomic radius.
• Ionic radius.
• Ionization energy.
• Electronegativity.

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Atomic Radius

• The distance from the center of an atoms nucleus
  to its outermost electron.
• Atoms get larger going down a group.
• Atoms get smaller moving from left to right
  across each period.

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Ionic Radius

• Atom loses electrons positive ion smaller.
• Atom gains electrons negative ion larger.
• Ion trend (Left vs. Right side).

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Ionization Energy

• The energy needed to remove one of an atoms
  electrons.
• Measure of how strongly an atom holds onto its
  outermost electron.
• Ionization energies decrease as you move down a
  group.
• Ionization energies increase as you move from
  left to right across a period.
• Opposite the atomic radius trends.

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Electronegativity

• Reflects the ability to attract electrons in a
  chemical bond.
• Related to its ionization energy and electron
  affinity.
• Increases as you move from left to right and
  decreases as you move down.

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The Bridge
mass
particles
MOLE
volume
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Molar Mass

• Distribute the subscript outside the ( ).
• List the elements in the compound.
• List the number of atoms for each.
• Look up the atomic mass for each and multiply by
  the number of atoms.
• Include significant figures and scientific
  notation as required.

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Mole Conversions

• Mass to moles.
• Moles to mass.
• Moles to particles.
• Particles to moles.
• Volume.

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Diatomic Molecules

• H2
• N2
• O2
• F2
• Cl2
• Br2
• I2

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Indicators of a Chemical Reaction

• Formation of a precipitate.
• Evolution of a gas.
• Color change.
• Absorption or release of heat.

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STOICHIOMETRY - EQUATIONS

• Stoichiometry the study of quantitative
  relationships that exist in chemical formulas and
  reactions.

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The Process

• Balance the equation.
• Identify the known and unknown.
• Convert the known units to moles
• Multiply by mole ratio.
• Moles of unknown / moles of known
• Convert the moles of unknown to the desired
  units.

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CompositionThe mass of each element in a
compound compared to the entire mass of the
compound.

• Solve for the molar mass
• Solve for each element using the formula
• part X 100
• whole
• The sum of the percentages should equal 100.
• Example.

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Empirical FormulaA formula that gives the
simplest whole number ratio of the atoms of the
elements.

• Assume 100g and convert all signs to grams.
• Convert grams of elements to moles.
• Divide all the elements by the lowest of moles
  to get the ratio.
• Write the empirical formula.
• Rounding
• 0.01-0.44 round DOWN
• 0.45-0.55 multiply by 2
• 0.56-0.99 round UP

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Empirical FormulaA formula that gives the
simplest whole number ratio of the atoms of the
elements.

• Determine the empirical formula for the compound
  that contains 80.38 Bi, 1.16 H, and 18.46
  O.

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Molecular FormulaThe formula that gives the
actual of atoms of each element in a molecular
compound.

• The molecular formula is a multiple of the
  empirical formula.

Add 2 more steps!!!! MM multiplier EM Distribu
te the multiplier!!!!!!
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Molecular FormulaThe formula that gives the
actual of atoms of each element in a molecular
compound.

• The molecular weight is 466.0 g and the empirical
  formula is C2H4O1. Determine the molecular
  formula.
• A compound is analyzed and determined to have an
  empirical formula of C6H8O and a molar mass of
  290 g/mol. What is the molecular formula?

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Empirical and Molecular Formulas

• Determine the empirical formula for compounds
  that have the following analyses
• 60.9 As and 39.1 S.
• 76.89 Re and 23.12 O.
• A 2.65 g sample of a salmon-colored powder
  contains 0.70 g of chromium, 0.65 g of sulfur,
  and 1.30 g of oxygen. The molar mass is 392.2.
  What is the formula of the compound?
• Determine the molecular formulas for compounds
  having the following empirical formulas and molar
  masses
• C2H4S molar mass 179g.
• C2H3O2 molar mass 119g.