ChemistryUnit 3

1
ChemistryUnit 3

• Formulas and Nomenclature

2
Formulas

• Use of symbols and subscripts to represent the
  composition of a molecule
• Ex H2O CO2 NH4OH Ca3(PO3)2

3
Element Symbols

• 1st letter is CAPITALIZED
• 2nd letter is lower case
• i.e. Tin is Sn not SN
• Why?
• SN is Sulfur Nitrogen

4
Element Symbols cont.

• Some symbols come from
• Latin
• i.e. Sodium (Na) comes from natrium
• Famous Scientists
• i.e. Curium (Cm) comes from Marie Curie
• What other categories can you find?
• planets, Greek gods, locations

5
How many?do as a class together

• NaCl
• ___ Na atoms ___ Cl atoms
• CuCl2
• ___ Cu atoms ___ Cl atoms
• Ca3(PO3)2
• ___ Ca ___ PO3 ___ P ___ O

1
1
2
1
6
2
2
3
6

• Try These with your partner
• Fe2O3
• ___ Fe ___ O
• Ba(OH)2
• ___ Ba ___ OH ___ O ___ H
• Al(NO3)3
• ___ Al ___ NO3 ___ N ___ O

2
3
2
2
2
1
3
1
3
9
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Oxidation Number (write small!!)

• Definition the charge on an ion
• Ion an electronically charged particle due to a
  gain or loss of electrons
• also called a radical
• ex Calcium
• Ca is an atom
• Ca2 is an ion

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Oxidation Number cont.

• Na loses 1 electron to become positively charged
• We write this as Na1

Na 11 and 11-
Na 1 11 and 10-
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Oxidation Number cont.

• Another Example
• Cl gains 1 electron to become negatively charged
• We write this as Cl1-

Cl 17 and 17-
Cl-1 17 and 18-
1-
gain 1 electron
Cl atom
Cl- ion
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Oxidation Number cont.

• Try This
• Mg loses 2 electrons
• What is the charge of the Mg ion?
• Mg2

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Multiple Oxidation States

• Some ions have more than one oxidation state
  (charge)
• ex Cu2S is copper (I) sulfide CuS is
  copper (II) sulfide
• (Roman Numerals Indicate Charge of Metal Ion)
• Note Names of ions can be found
• on the back of periodic table

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Polyatomic Ions
many

• Poly means
• Ions made up of more than one atom
• Definition A group of atoms which behaves as a
  single unit and has an electric charge
• Can be found on back of periodic table
• Examples
• SO42- sulfate
• SO32- sulfite
• Note DONT CHANGE THEIR ENDINGS TO ide

NO3 1- nitrate
NO21- nitrite
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Writing Formulas

• Charges must add up to 0
• (get charges from
• back of your Periodic Table)
• 2) Find the Least Common Multiple to determine
  what subscript to use

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Writing Formulas

• Examples
• sodium chloride
• barium chloride
• copper (II) iodide
• aluminum sulfate
• Note Do NOT include charges in the formula

NaCl
Cl1-
Na1
BaCl2
Cl1-
Ba2
CuI2
I1-
Cu2
Al2 (SO4)3
SO42-
Al3
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Naming Compounds IUPAC Nomenclature

• Binary Compounds
• made up of 2 elements
• 1st Name the positive ion
• 2nd Name the negative ion
• (See back of Periodic Table)
• Ex NaCl
• Al2S3

sodium chloride
aluminum sulfide
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Naming Compounds cont.

• B) Compounds with Polyatomic Ions
• 1st Name the positive ion
• 2nd Name the polyatomic ion (do not change its
  ending)
• Ex CuSO4
• AlPO4
• Ca(OH)2
• Mg(CN)2
• Note There is one positively charged polyatomic
  ion
• Ammonium NH41

copper (II) sulfate
aluminum phosphate
calcium hydroxide
magnesium cyanide
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Diatomic Molecules

• There are 7 atoms that exist in pairs

Write with 2 atoms! N2, O2, F2, Cl2, Br2, I2, H2
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Chemical Changes

• 2 H2 (g) O2 (g) 2 H2O (g)

?
Products
Reactants
Reactantsthe original substances on the left
hand side of the arrow
Products the substances produced on the right
hand side of the arrow
Physical State (s) (g) (l) (aq) (c)
(v) O2 ? AgCl ?
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Coefficients

• Numbers in front of the formula to tell us how
  many there are
• Coefficients are NEVER in the middle of a
  compound always in FRONT
• 2 H2O means 2 water molecules
• ___ Hs ____ Os
• Try this
• 2 Ca(OH)2 means ___ calcium hydroxide molecules
• _____ Cas _____ OHs _____ Os _____ Hs

4
2
2
2
4
4
4
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Balancing Equations

• Law of Conservation of Mass
• matter can neither be created nor destroyed
• of atoms on the left atoms on the right

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Steps to Balancing Equations
1) Do in pencil
2) Determine the Reactants and Products
3) Write an equation
4) Count of atoms of each element on both sides
of the change arrow
5) Change coefficients to make the same number of
each type of atom on each side
6) Check by counting atoms

• Remember
• NEVER CHANGE SUBSCRIPTS
• COEFFICIENTS ALWAYS GO IN FRONT OF FORMULA

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Sample Problems
2

• Mg(s) HCl(aq) ? MgCl2(aq) H2(g)
• Al(NO3)3(aq) KBr(aq)? AlBr3(s) KNO3(aq)
• Ca(OH)2(aq) H2CO3(aq) ? CaCO3(s) H2O(l)

3
3
2
23
2 Al(s) 6 HCl(aq) ? 2 AlCl3(aq) 3 H2(g)

• underline the side with the products
• circle the side with the reactants
• draw hearts around the coefficients
• make a smiley face around the states of matter
• draw a Christmas tree around the subscripts
• draw a pentagon around the symbol that means
  yield

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Classifying Chemical Changes

• Displacement
• Single Displacement
• one element displaces another
• ex
• Cl2 (g) 2 KBr (s) ? Br2 (l) 2 KCl (s)

Positive ions switch with positive ions Negative
ions switch with negative ions
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Single Displacement
Cu(s) 2AgNO3(aq) ? Cu(NO3)2(aq) 2Ag(s)
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Single Displacement

• Names
• Formulas
• Balance
• aluminum copper (II) chloride ? ________
  ________
• copper silver nitrate ?
  ________ ________

aluminum chloride
copper
3
2
3
2
Al CuCl2 ? AlCl3
Cu
copper (II) nitrate
silver
2
2
Cu AgNO3 ? Cu(NO3)2
Ag
zinc chloride
hydrogen
zinc hydrogen chloride ? ________
________
2
Zn HCl ?
ZnCl2 H2
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Double Displacement

• ions exchange between compounds
• compound compound ? 2 new compounds
• Ex
• BaCl2 Na2SO4 ? BaSO4 2 NaCl

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Double Displacement cont

• Demos
• potassium iodide lead (II) nitrate ?
• Sodium carbonate calcium nitrate ?

potassium nitrate lead (II) iodide
KI Pb(NO3)2 ? KNO3 PbI2
2
2
calcium carbonate sodium nitrate
Na2CO3 Ca(NO3)2 ? CaCO3 NaNO3
2
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Decomposition

• One compound breaks up
• 2 H2O2 ? 2 H2O O2
• 2 KClO3 ? 2 KCl 3 O2
• CuCO3 ? CuO CO2

D
Doesnt it look like a little flame?
D
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Synthesis

• One compound is created from two elements
• Demos/Labs

Zn S ? ZnS
2 H2 O2 ? 2 H2O
4 Fe 3 O2 ? 2 Fe2O3
2 Mg O2 ? 2 MgO
3 Mg N2 ? Mg3N2
Endothermic
requires heat feels cold temp ?
gives off heat feels warm temp ?
Exothermic