Monday, Jan 9

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Monday, Jan 9 Begin chapter 7 Chemical
Formulas and Compounds Finals are NEXT WEEK.
Chapter 7 will be covered in the Final Today
Monoatomic and polyatomic ion names using
flashcards. QUIZ ON NAMES TOMORROW!!
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Chemistry Chapter 7
Chemical Formulas and Chemical Compounds
Heart cell rhythm depends on the opening and
closing of a complex series of valves on the cell
membrane, called ion channels. Some valves let
certain ions like potassium (K) flow out, others
let different ions like sodium (Na) flow in.
There are also pumps that actively move ions one
direction or another.
LOHS Chemistry Schrempp Fall 2004 to view
online drschrempp.com
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Review Ions

• Cation A positive ion
• Mg2, NH4
• Anion A negative ion
• Cl-, SO42-
• Ionic Bonding Force of attraction between
  oppositely charged ions.

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Review Predicting Ionic Charges
Group 1
Lose 1 electron to form 1 ions
H
Li
Na
K
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Review Predicting Ionic Charges
Group 2
Loses 2 electrons to form 2 ions
Be2
Mg2
Ca2
Ba2
Sr2
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Review Predicting Ionic Charges
Group 13
Loses 3 electrons to form 3 ions
B3
Al3
Ga3
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Review Predicting Ionic Charges
Group 14
Lose 4 electrons or gain 4
electrons?
Neither! Group 13 elements rarely form ions.
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Review Predicting Ionic Charges
Nitride
N3-
Group 15
Gains 3 electrons to form 3- ions
P3-
Phosphide
As3-
Arsenide
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Review Predicting Ionic Charges
Oxide
O2-
Gains 2 electrons to form 2- ions
Group 16
S2-
Sulfide
Se2-
Selenide
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Review Predicting Ionic Charges
F1-
Br1-
Fluoride
Bromide
Group 17
Gains 1 electron to form 1- ions
Cl1-
Chloride
I1-
Iodide
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Review Predicting Ionic Charges
Group 18
Stable Noble gases do not form ions!
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Predicting Ionic Charges
Groups 3 - 12
Many transition elements
have more than one possible oxidation state.
Iron(II) Fe2
Iron(III) Fe3
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Predicting Ionic Charges
Groups 3 - 12
Some transition elements
have only one possible oxidation state.
Zinc Zn2
Silver Ag
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Chloride Iron(II) Lead(II) CO32- Hydroxide CH3COO-
Cl- Fe2 Pb2 Carbonate OH- Acetate
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Writing Ionic Compound Formulas
Example Barium nitrate
1. Write the formulas for the cation and anion,
including CHARGES!
( )
Ba2
2. Check to see if charges are balanced.
NO3-
2
Not balanced!
3. Balance charges , if necessary, using
subscripts. Use parentheses if you need more than
one of a polyatomic ion.
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Writing Ionic Compound Formulas
Example Ammonium sulfate
1. Write the formulas for the cation and anion,
including CHARGES!
( )
NH4
SO42-
2. Check to see if charges are balanced.
2
3. Balance charges , if necessary, using
subscripts. Use parentheses if you need more than
one of a polyatomic ion.
Not balanced!
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Writing Ionic Compound Formulas
Example Iron(III) chloride
1. Write the formulas for the cation and anion,
including CHARGES!
Fe3
Cl-
2. Check to see if charges are balanced.
3
3. Balance charges , if necessary, using
subscripts. Use parentheses if you need more than
one of a polyatomic ion.
Not balanced!
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Writing Ionic Compound Formulas
Example Aluminum sulfide
1. Write the formulas for the cation and anion,
including CHARGES!
Al3
S2-
2. Check to see if charges are balanced.
2
3
3. Balance charges , if necessary, using
subscripts. Use parentheses if you need more than
one of a polyatomic ion.
Not balanced!
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Writing Ionic Compound Formulas
Example Magnesium carbonate
1. Write the formulas for the cation and anion,
including CHARGES!
Mg2
CO32-
2. Check to see if charges are balanced.
They are balanced!
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Writing Ionic Compound Formulas
Example Zinc hydroxide
1. Write the formulas for the cation and anion,
including CHARGES!
( )
Zn2
OH-
2. Check to see if charges are balanced.
2
3. Balance charges , if necessary, using
subscripts. Use parentheses if you need more than
one of a polyatomic ion.
Not balanced!
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Writing Ionic Compound Formulas
Example Aluminum phosphate
1. Write the formulas for the cation and anion,
including CHARGES!
Al3
PO43-
2. Check to see if charges are balanced.
They ARE balanced!
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Naming Ionic Compounds

• 1. Cation first, then anion
• 2. Monatomic cation name of the element
• Ca2 calcium ion
• 3. Monatomic anion root -ide
• Cl- chloride
• CaCl2 calcium chloride

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Naming Ionic Compounds(continued)
Metals with multiple oxidation states

• - some metal forms more than one cation
• - use Roman numeral in name
• PbCl2
• Pb2 is cation
• PbCl2 lead(II) chloride

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Molecular Compounds- made of neutral atoms
sharing electrons form neutral molecules
2
types of formulas
molecular formula- represents a molecule
C6H6 empirical formulas - simplest ratio
of atoms (formula units are always empirical
formulas)
CH
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diatomic molecule - 2 atoms of the same element
covalently bonded together
There are 7 diatomic elements and they form the
shape of a 7 on the periodic table except for H
which is always an oddball
H2 N2 O2 F2 Cl2 Br2 I2
Only diatomic when pure element not necessarily
when forming a compound
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(No Transcript)
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Use prefixes to name molecular compounds
prefix subscript mono no
subscript (1 atom) di
2 tri 3
tetra 4
penta 5
hexa 6
hepta 7 octa 8
nona 9 deca 10

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• Rules for molecular compounds
• The less electronegative element is given 1st and
  only given a prefix if it has a subscript gt1
  (never start a name with mono)
• 2. Second element- add a prefix and add ide
  (drop prefix ending if first letter in the name
  of the element is a vowel)
• P4O10 tetraphosphorous decoxide

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Acids
endings change -ate to -ic H2SO4
sulfuric -ite to -ous H2SO3
sulfurous
Important acids to know HCl hydrochloric HNO3
nitric H3PO4 phosphoric HC2H3O2 acetic
(also CH3COOH) H2CO3 carbonic
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Naming Binary Molecular Compounds

• - Compounds between two nonmetals
• - First element in the formula is named first.
• - Second element is named as if it were an anion.
• - Use prefixes
• - Only use mono on second element -

P2O5
diphosphorus pentoxide
CO2
carbon dioxide
CO
carbon monoxide
N2O
dinitrogen monoxide
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• Tuesday, Jan 24
• Movie
• Something the Lord Made
• After watching the movie (2 days) you will write
  a 1-page, single spaced, typewritten paper
  including
• One paragraph summarizing the movie, and
  including names, settings and general theme.
• A paragraph on how racial differences impacted
  the story
• a paragraph on how you see things the same, or
  different today
• A conclusion of your overall thoughts

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Calculating Formula Mass
Calculate the formula mass of magnesium
carbonate, MgCO3
24.31 g 12.01 g 3(16.00 g)
84.32 g
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• Rules for Assigning Oxidation Numbers
• The oxidation number of an atom in the elemental
  state is zero.Example Cl2 and Al both are 0
• The oxidation number of a monatomic ion is equal
  to its charge.Example In the compound NaCl, the
  sodium has an oxidation number of 1 and the
  chlorine is 1-.
• The algebraic sum of the oxidation numbers in the
  formula of a compound is zero.Example the
  oxidation numbers in the NaCl above add up to 0

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Rules for Assigning Oxidation Numbers 4. The
oxidation number of hydrogen in a compound is 1,
except when hydrogen forms compounds called
hydrides with active metals, and then it is
1-.Examples H is 1 in H2O, but 1- in NaH
(sodium hydride). 5. The oxidation number of
oxygen in a compound is 2-, except in peroxides
when it is 1-, and when combined with fluorine.
Then it is 2.Example In H2O the oxygen is 2-,
in H2O2 it is 1-.
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Rules for Assigning Oxidation Numbers 6. The
algebraic sum of the oxidation numbers in the
formula for a polyatomic ion is equal to the
charge on that ion. Example in the sulfate ion,
SO42-, the oxidation numbers of the sulfur and
the oxygens add up to 2-. The oxygens are 2-
each, and the sulfur is 6.
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Calculating Percentage Composition
Calculate the percentage composition of magnesium
carbonate, MgCO3.
From previous slide 24.31 g 12.01 g
3(16.00 g) 84.32 g
100.00
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Formulas
Empirical formula the lowest whole number ratio
of atoms in a compound.
Molecular formula the true number of atoms of
each element in the formula of a compound.

• molecular formula (empirical formula)n n
  integer
• molecular formula C6H6 (CH)6
• empirical formula CH

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Formulas (continued)
Formulas for ionic compounds are ALWAYS empirical
(lowest whole number ratio).
Examples
NaCl
MgCl2
Al2(SO4)3
K2CO3
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Formulas (continued)
Formulas for molecular compounds MIGHT be
empirical (lowest whole number ratio).
Molecular
C6H12O6
C12H22O11
H2O
Empirical
H2O
CH2O
C12H22O11
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Empirical Formula Determination

• Base calculation on 100 grams of compound.
• Determine moles of each element in 100 grams of
  compound.
• Divide each value of moles by the smallest of the
  values.
• Multiply each number by an integer to obtain all
  whole numbers.

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Empirical Formula Determination
Adipic acid contains 49.32 C, 43.84 O, and
6.85 H by mass. What is the empirical formula of
adipic acid?
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Empirical Formula Determination(part 2)
Divide each value of moles by the smallest of the
values.
Carbon
Hydrogen
Oxygen
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Empirical Formula Determination(part 3)
Multiply each number by an integer to obtain all
whole numbers.
Carbon 1.50
Hydrogen 2.50
Oxygen 1.00
x 2
x 2
x 2
3
5
2
C3H5O2
Empirical formula
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Finding the Molecular Formula
The empirical formula for adipic acid is C3H5O2.
The molecular mass of adipic acid is 146 g/mol.
What is the molecular formula of adipic acid?
1. Find the formula mass of C3H5O2
3(12.01 g) 5(1.01) 2(16.00) 73.08 g
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Finding the Molecular Formula
The empirical formula for adipic acid is C3H5O2.
The molecular mass of adipic acid is 146 g/mol.
What is the molecular formula of adipic acid?
2. Divide the molecular mass by the mass given by
the emipirical formula.
3(12.01 g) 5(1.01) 2(16.00) 73.08 g
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Finding the Molecular Formula
The empirical formula for adipic acid is C3H5O2.
The molecular mass of adipic acid is 146 g/mol.
What is the molecular formula of adipic acid?
3. Multiply the empirical formula by this number
to get the molecular formula.
3(12.01 g) 5(1.01) 2(16.00) 73.08 g
(C3H5O2) x 2
C6H10O4
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• For Test
• Know how to tell the difference between ionic and
  covalent compounds
• Know how to name ionic (NaI, CaCl2, KClO4, etc)
  and covalent (NO, N2O4, P4O10, CI4, etc)
  compounds
• Know how to do the reverse Write the formula for
  ionic and covalent compounds when given the name
  (carbon tetraiodide, silver oxide, iron(II)
  chromate, phosphorus pentabromide, sulfur
  trioxide, potassium chlorate)

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• For Test
• Know how to assign oxidation numbers to each
  element on simple compounds (H2SO4, HCl, SO2,
  N2O5, P4O10, etc) (know the rules or have them
  on your notecard)
• Know common acid names (table 7-5, pg 214 in
  text)
• Know how to calculate molar (formula) mass
  (Ba(NO3)2, Al2S3, NaNO3, etc)
• Know how to do gram to mole and gram to molecule
  conversions (and vice-versa)

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The Mole
One mole contains 6.02 X 1023 Particles Molar
Mass (Formula mass) The number of grams in one
mole of a substance (calculate from atomic mass)
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Mole calculations
Converting from grams to moles or molecules, use
conversion factors
Grams of A
1 mol
Moles of A
Molar mass of A
Moles of A
6.02 x 1023 particles
molecules of A
1 mol