Chemical Names and Formulas

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• Chemical Names and Formulas

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Molecules

• A molecule is the smallest electrically neutral
  unit of a substance that still has the properties
  of the substance.
• 1. Monatomic - consist as a single atom (Ex
  Noble gases)
• 2. Diatomic molecule -7 exist in nature BrINCl
  HOF
• 3. Triatomic molecule ( Ex O3 - ozone)

He
Br2 I2 N2 Cl2 H2 O2 F2
(means 2) atoms
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• Chemical Formula shows the kinds and numbers of
  atoms in the smallest representative unit of the
  substance (formula unit)

H2O
H2O2
Whats the difference between these two
formulas? When you change the subscripts the
formula no longer represents that compound.
REMEMBER!!!! H Element symbol always begins
with a capital letter Na If
symbol has two letters, the second
letter is always lowercase
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Chemical Formulas

• How to read formulas
• H2O
• 2 hydrogen atoms
• 1 oxygen atom
• Ca(OH)2 Number outside the parenthesis
  distributes to inside the parenthesis
• 1 calcium atom
• 2 oxygen atoms
• 2 hydrogen atoms

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Explain the following

• MgCl2 What elements are present? How many?
• Mg -
• Cl -
• Pb(NO3)2 What elements are present? How many?
• Pb -
• N -
• O -

1
2
1
2
6
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Ionic Charges of Representative Elements
1A 2A 3A 4A 5A 6A 7A 8A
Li Na K Rb Cs Be2 Mg 2 Ca 2 Sr 2 Ba 2 Al3 N3- P3- As3- O2- S2- Se2- F- Cl- Br- I-
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• Oxidation Numbers how many electrons an atom
  would gain or lose to follow the octet rule
• (also called its charges)

1
2
-1
-2
-3
3
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Charges of Transition Metals

• These transition metals have more than one
  charge
• Cr2 or 3 Cu or 2
• Mn2 or 3 Sn2 or 4
• Fe2 or 3 Pb2 or 4
• Co2 or 3 Ni2 or 3
• Hg1 or 2 Au1 or 3
• Sc2 or 3 Hg1 or 2

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I. Writing Formulas for Binary Ionic Compounds

• Rules
• Write symbol and charge for both cation and
  anion.
• Crisscross charges, drop the charge and write as
  subscripts.
• CHECK!! The formula must be in the lowest
  possible ratio.

The cation is always written first!
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Example Problems

• Write formulas for these compounds
• calcium iodide

2
-
I
Ca
2
1
CaI2
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Tin (IV) oxide
4
-2
O
Sn
2
4
Sn2O4
SnO2
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White Board Practice
Aluminum sulfide
-2
3
Al
S
2
3
Al2S3
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Beryllium Oxide
-2
2
Be
O
2
2
BeO
Be2O2
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II. Naming Binary Ionic Compounds

• 1.) Use the name of the cation.
• Use Roman Numerals if Transition Metal.
• 2.) Name the anion and change ending to -ide.

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Naming Binary Ionic Compounds
2
-1
-2
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Find Sn Where is it located?

• SnS2

Use Roman Numerals
Tin
(IV)
Sulfide
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WHITE BOARD practice problems
A.) KCl
B.) CuBr2
C.) AlF3
D.) MgO
E.) MnI2
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Al3 P-3
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White Board Practice
1.) K S-2
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2.) Al3 I-
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3.) Ag O-2
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4.) Ni2 O-2
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5.) Pb4 O-2
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Polyatomic Ions

• Tightly bound groups of atoms that behave as a
  unit and carry a charge.

Examples
Ammonium NH4
Cyanide CN-
Sulfite SO32-
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III. Writing Formulas for Ternary Ionic Compounds

• A. Contain a polyatomic ion
• B. Same rules as for binary ionic compounds.
• One addition Use parenthesis if there is more
  than one polyatomic ion
• Ex
• Calcium Hydroxide
• Ca2 OH-
• CaOH2

Ca(OH)2
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• Boron acetate
• B3 C2H3O2-1
• Magnesium Dichromate
• Mg2 Cr2O7-2

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White Board Practice Problems

• Write formulas for the following ternary
  ionic compounds
• Calcium Carbonate
• Barium Nitrite
• Potassium Sulfate
• Magnesium Phosphate

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IV. Naming Ternary Ionic Compounds

• Same rules as for naming binary ionic compounds
• Name the cation
• Use a Roman numeral if necessary
• Name the anion (change ending to ide) Polyatomic
  ions will stay the same!!

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White Board Practice Problems

• Name the following ternary ionic compounds
• NaCN
• NH4ClO
• Li2SO3
• CaC2O4
• Al(OH)3
• Sn3(PO4)2

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Ionic Compounds- Polyatomic IonsLeft Side of
Spiral
Cl OH SO4 PO4 NO3
Zn2
NH4
K
Ca
Fe3
-1
-2
-3
-1
-1


2
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V. Rules for Naming Covalent Compounds

• 1. Prefixes are used to show how many atoms of
  each element are present in the compound

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Rules for Naming Covalent Compounds

• 2. Second element is written with an ide ending.
• All binary compounds, both ionic and covalent
  end in ide.
• 3. The vowel at the end of the prefix is dropped
  when the name of the element begins with the same
  vowel.
• Ex monoxide, not monooxide

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Rules for Naming Covalent Compounds

• 4. Mono is omitted if there is just a single
  atom on the first element in the name.
• Ex CO2
• carbon dioxide not monocarbon dioxide

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Naming Binary Covalent Compounds

• 1.) CO
• 2.) SO2
• 3.) N2O
• 4.) CCl4
• 5.) N2O5
• 6.) NO4
• 7.) OF2

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Writing Formulas for Binary Covalent Compounds

• Write the formulas for the following compounds.
• 1. carbon monochloride
• 2. nonacarbon tetrachloride
• 3. heptabromine dioxide
• 4. phosphorus trichloride
• 5. octanitrogen pentafluoride

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Ionic vs. Covalent

• Are the following compounds ionic or covalent?

a. H2O
f. dinitrogen tetraoxide
g. FeS
b. Sodium chloride
c. CuSO4
h. Cobalt (III) chloride
d. CO
i. H2S
e. Lithium hydroxide
j. PF3
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Naming Acids

• HCl hydrochloric acid
• H2SO4 sulfuric acid
• HNO3 nitric acid
• HC2H3O2 acetic acid
• H3PO4 phosphoric acid
• H2CO3 carbonic acid

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ECHS Relay Challenge

• 1.) How many atoms of fluorine are present in
  CF4?
• 2.) How many atoms of carbon are present in CF4?
• 3.) What is the formula for carbon monoxide?
• 4.)What is the formula for lithium chloride?
• 5.) What is the formula for the compound formed
  by iron (II) and carbonate ions?
• 6.) What is the formula for aluminum hydroxide?
• 7.) What is the formula for lead (IV) oxide?
• 8.) What is the formula for magnesium nitrate?
• 9.) What is the name of the compound NH3? CCl4?
• 10.) What is the cation in iron (II) oxide?
• 11.) What is the name of the compound N2O2? H2O2?
• 12.) What is the formula for sulfur trioxide?
• 13.) What is the formula for dinitrogen
  tetrafluroide?
• 14. )What prefix is used to represent ten?
• 15.) How do you know a compound is covalent when
  looking at the chemical formula?
• 16.) Using the ion pairs listed, write the
  correct chemical formula that the ions would
  form
• a. Cr3 I- b.
  Cu2 O-2 c. Li S-2
• 17.) What is the oxidation number for iron (II)
  in iron (II) oxide?
• 18. Write the names for the compound FeO and
  Fe2O3. Justify why the names you wrote are
  correct.