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Writing and Naming Binary Compounds & Hydrates. You will need: A periodic table A list of common polyatomic ions Patience and understanding. Generic Chemical Formulas. MgCl 2. Chemical symbols. Subscript. Binary Compounds.

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Writing and Naming Binary Compounds & Hydrates

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Writing and naming binary compounds hydrates

Writing and Naming

Binary Compounds & Hydrates

You will need:

A periodic table

A list of common polyatomic ions

Patience and understanding


Writing and naming binary compounds hydrates

Generic Chemical Formulas

MgCl2

Chemical symbols

Subscript


Writing and naming binary compounds hydrates

Binary Compounds

A chemical compound consisting of two parts, a CATION (+) and an ANION (-)

Examples:

  • Two elements chemically bonded

  • 2. An element and a polyatomic ion chemically bonded

  • 3. Two polyatomic ions chemically bonded


Writing and naming binary compounds hydrates

Binary Compounds

Have two parts

Left side is the cation

Positively charged

Right side is the anion

Negatively charged

MgCl2


Writing and naming binary compounds hydrates

Hydrates

A hydrate is a binary compound that has water attached to its ions and the water is a PART of the chemical formula.

Naming hydrates uses terms that indicate the number of water molecules.


Writing and naming binary compounds hydrates

Hydrates

CaSO4 • 2 H2O

Calcium sulfate dihydrate

Binary compound

AlO3 • 3 H2O

Aluminum oxide trihydrate

Binary compound

CuSO4 • 5 H2O

Copper (II) sulfate pentahydrate

Binary compound


Writing and naming binary compounds hydrates

Writing Binary Formulas

6 Steps

1. Write chemical symbols for cation and anion

2. Add cation and anion oxidation numbers as superscripts

3. Check to see if oxidation numbers add to zero

4. If yes, leave as written

5. If no, make oxidation numbers subscripts

6. Check for lowest whole number ratio


Writing and naming binary compounds hydrates

Writing Binary Formulas

Write the formula for sodium chloride.

+

-

Na Cl

3

4

1

2

Add cation and anion oxidation numbers as superscripts

Check to see if oxidation numbers add to zero

If yes, leave as written

Write chemical symbols for the cation and anion


Writing and naming binary compounds hydrates

Writing Binary Formulas

Write the formula for magnesium nitride

+2

-3

Mg N

3

2

3

4

5

1

2


Writing and naming binary compounds hydrates

Writing Binary Formulas

Write the formula for hydrogen carbonate

+

-2

H CO3

2

3

4

5

1

2


Writing and naming binary compounds hydrates

Writing Binary Formulas

Write the formula for magnesium phosphate

-3

+2

(

)

Mg PO4

2

3

3

4

5

1

2


Writing and naming binary compounds hydrates

Writing Binary Formulas

For transition metals the oxidation number is given in parentheses, In Roman numerals.

Write the formula for iron (III) oxide.

Fe +3 O -2

Fe2 O3


Writing and naming binary compounds hydrates

Writing Binary Formulas

  • For hydrates, that is, binary compounds with water (hydrate) attached:

  • nickel (II) sulfate hexahydrate

  • Write the formula of the binary compound (first part) using rules 1-4:

    • NiSO4

  • b. Insert a “raised dot” after the binary compound:

  • NiSO4●

  • Use name prefix to note the number of water molecules (hydrates):

    • NiSO4 ●6 H2O


  • Writing and naming binary compounds hydrates

    Polyatomic Ions (learn these)

    Table 4Page 619


    Writing and naming binary compounds hydrates

    More Polyatomic Ions

    (learn these, too)


    Writing and naming binary compounds hydrates

    A quick review of hydrates.


    Writing and naming binary compounds hydrates

    Naming Binary Formulas

    Binary Compound = CATION + ANION

    First: Get a periodic table and table of common polyatomic ions

    Next: Determine the cation and anion in the compound

    Then: Note the cation and apply the 5 naming rules IN ORDER


    Writing and naming binary compounds hydrates

    Naming Binary Formulas

    5 Rules that begin with the location or kind of the CATION

    Rule 1. For elements in the first two columns of the periodic table

    Rule 2. For elements from group 3 up to the staircase

    Rule 3. For elements to the right (above) the staircase

    Rule 4. For CATIONS that are polyatomic ions

    Rule 5. For hydrates


    Writing and naming binary compounds hydrates

    Naming Binary Formulas – Rule 1

    • For cations (elements) in the first two columns of the periodic

    • table:

    • MgCl2 LiOH

    • Cation: Write the name of the element as the first part of the compound:

      • magnesiumlithium

  • b. Anion: Write the name of the element with an ide ending:

  • magnesium chloride

  • Anion: Write the name of the polyatomic ion:

    • lithium hydroxide

  • or


    Writing and naming binary compounds hydrates

    Naming Binary Formulas – Rule 2

    • For cations (elements) from the third group of the periodic table up to the “staircase”

    • FeCl2 Cu2SO4

    • Cation: Name of element with Roman Numeral to show oxidation number:

      • iron (II)copper (I)

  • b. Anion: Name the element with an ide ending:

  • iron (II) chloride

  • Anion: Name the polyatomic ion:

    • copper (I) sulfate

  • Exceptions to rule:

    Ag+1 Zn+2

    Cd+2 Al+3

    (Use Rule 1)

    or


    Writing and naming binary compounds hydrates

    Naming Binary Formulas – Rule 3

    • For cations (elements) to the right (above) the “staircase”

    • CO2 CO N4S3

    • Count the “number” of each element. (C-1, O-2 C-1, O-1N-4, S-3)

    • b. Use prefixes (mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca) to indicate the number of each atom present.

    • Do not use “mono” if there is only one of the first element in the compound.

    • CO2 N4S3

    • CARBON DIOXIDE

    CO

    TETRANITROGEN TRISULFIDE

    CARBON MONOXIDE


    Writing and naming binary compounds hydrates

    Naming Binary Formulas – Rule 4

    • For cations that are polyatomic ions:

    • NH4Cl NH4OH

    • Cation: Name the polyatomic ion:

      • ammoniumammonium

  • b. Anion: Name the element with an ide ending:

  • ammonium chloride

  • Anion: Name the polyatomic ion:

    • ammonium hydroxide

  • or


    Writing and naming binary compounds hydrates

    Naming Binary Formulas – Rule 5

    • For hydrates, that is, binary compounds with water (hydrate) attached:

    • NiSO4● 6 H2O

    • Name of the binary compound (first part) using rules 1-4:

      • nickel (II) sulfate

  • b. Note the number of water molecules (hydrates) by using prefixes:

    • nickel (II) sulfatehexahydrate


  • Writing and naming binary compounds hydrates

    Rest stop!

    Inhale and breathe easy!

    The next group of slides goes into some detail about oxidation numbers in covalent compounds and in polyatomic ions. For this presentation, a periodic table that shows electronegativities is most helpful.


    Covalent compounds

    Covalent Compounds

    Example: phosphate ion

    Electronegativity:

    2.1

    3.5

    -2

    P O43-

    Polyatomic ion with a charge = -3

    Since oxygen is the more electronegative element, it will have its normal oxidation number.


    Covalent compounds1

    Covalent Compounds

    Example:

    • + 5

    • 8

    • - 3

    +5

    -2

    P O43-

    The phosphate ion has a charge of negative three, so the oxidation numbers must add up to the total charge of the ion.


    Ionic compounds with polyatomics

    Ionic Compounds with Polyatomics

    Example:

    +2

    Ca SO4

    This is an ionic compound, so the charge of the metal cation is its oxidation number


    Ionic compounds with polyatomics1

    Ionic Compounds with Polyatomics

    Example:

    +2

    Ca SO4

    The anion is a polyatomic ion, sulfate, and the charge of sulfate is negative two. So the oxidation numbers of sulfur and oxygen must add to -2


    Ionic compounds with polyatomics2

    Ionic Compounds with Polyatomics

    Example:

    2.5

    3.5

    +2

    -2

    Ca SO4

    Oxygen is the more electronegative of the two, so it keeps its normal oxidation number.


    Ionic compounds with polyatomics3

    Ionic Compounds with Polyatomics

    Example:

    +6

    -2

    Ca SO4

    +2

    Sulfur and the four oxygen atoms must add to negative two (the charge of the sulfate anion).


    Ionic compounds with polyatomics4

    Ionic Compounds with Polyatomics

    Example:

    Pb(OH)4

    This is an ionic compound, so the charge of the metal cation is its oxidation number. But this is a transition metal, so we cannot know it from its position on the periodic table.


    Ionic compounds with polyatomics5

    Ionic Compounds with Polyatomics

    Example:

    +4

    -1

    Pb(OH)4

    But the anion, the hydroxide ion, carries a charge of negative one. All four hydroxides are negative one, but since the compound is neutral, the oxidation number of lead must balance it out.


    Ionic compounds with polyatomics6

    Ionic Compounds with Polyatomics

    Example:

    3.5

    2.1

    +4

    -2

    Pb(OH)4

    Within the anion, oxygen is the more electronegative of the two elements, and keeps its normal oxidation number.


    Ionic compounds with polyatomics7

    Ionic Compounds with Polyatomics

    Example:

    +4

    -2

    +1

    Pb(OH)4

    Within the hydroxide ion, the oxygen and hydrogen must add to the charge of the ion, -1


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