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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.

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Presentation on theme: "Writing and Naming Binary Compounds & Hydrates You will need: A periodic table A list of common polyatomic ions Patience and understanding."— Presentation transcript:

1 Writing and Naming Binary Compounds & Hydrates You will need: A periodic table A list of common polyatomic ions Patience and understanding

2 Generic Chemical Formulas MgCl 2 Chemical symbols Subscript

3 Binary Compounds 1. Two elements chemically bonded 2. An element and a polyatomic ion chemically bonded 3. Two polyatomic ions chemically bonded A chemical compound consisting of two parts, a CATION (+) and an ANION (-) Examples:

4 Binary Compounds Have two parts Left side is the cation Positively charged Right side is the anion Negatively charged MgCl 2

5 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.

6 1 mono mono 2 di di 3 tri tri 4 tetra tetra 5 penta penta 6 hexa hexa 7 hepta hepta 8 octa octa 9 nona nona 10 deca deca

7 Hydrates CaSO 4 2 H 2 OCalcium sulfate dihydrate CuSO 4 5 H 2 O AlO 3 3 H 2 O Aluminum oxide trihydrate Copper (II) sulfate pentahydrate Binary compound

8 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

9 Writing Binary Formulas Write the formula for sodium chloride. Na Cl Write chemical symbols for the cation and anion Add cation and anion oxidation numbers as superscripts Check to see if oxidation numbers add to zero If yes, leave as written

10 Writing Binary Formulas Write the formula for magnesium nitride Mg N

11 Writing Binary Formulas Write the formula for hydrogen carbonate H CO

12 Writing Binary Formulas Write the formula for magnesium phosphate Mg PO ()

13 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 Fe 2 O 3

14 Writing Binary Formulas For hydrates, that is, binary compounds with water (hydrate) attached: nickel (II) sulfate hexahydrate a.Write the formula of the binary compound (first part) using rules 1-4: NiSO 4 b. Insert a “raised dot” after the binary compound: NiSO 4 ● c.Use name prefix to note the number of water molecules (hydrates): NiSO 4 ● 6 H 2 O

15 Polyatomic Ions (learn these) Table 4Page 619 NameFormula Ammonium NH 4 + NH 4 + Acetate C 2 H 3 O 2 - C 2 H 3 O 2 - Chlorate ClO 3 - ClO 3 - Hydroxide OH - OH - Nitrate NO 3 - NO 3 - Carbonate CO 3 2- CO 3 2- Sulfate SO 4 2- SO 4 2- Phosphate PO 4 3- PO 4 3-

16 More Polyatomic Ions (learn these, too) NameFormula Hydrogen carbonate (bicarbonate) HCO 3 - HCO 3 - Nitrite NO 2 - NO 2 - Permanganate MnO 4 - MnO 4 - Sulfite SO 3 2- SO 3 2-

17 A quick review of hydrates.

18 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

19 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

20 Naming Binary Formulas – Rule 1 For cations (elements) in the first two columns of the periodic table: MgCl 2 LiOH a.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 c.Anion: Write the name of the polyatomic ion: lithium hydroxide or

21 Naming Binary Formulas – Rule 2 For cations (elements) from the third group of the periodic table up to the “staircase” FeCl 2 Cu 2 SO 4 a.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 c.Anion: Name the polyatomic ion: copper (I) sulfate or Exceptions to rule: Ag +1 Zn +2 Cd +2 Al +3 (Use Rule 1)

22 Naming Binary Formulas – Rule 3 For cations (elements) to the right (above) the “staircase” CO 2 CO N 4 S 3 a.Count the “number” of each element. (C-1, O-2 C-1, O-1 N-4, S-3) b. Use prefixes (mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca) to indicate the number of each atom present. b.Do not use “mono” if there is only one of the first element in the compound. c. CO 2 N 4 S 3 CARBON DIOXIDE TETRANITROGEN TRISULFIDE CARBON MONOXIDE CO

23 Naming Binary Formulas – Rule 4 For cations that are polyatomic ions: NH 4 Cl NH 4 OH a.Cation: Name the polyatomic ion: ammoniumammonium b. Anion: Name the element with an ide ending: ammonium chloride c.Anion: Name the polyatomic ion: ammonium hydroxide or

24 Naming Binary Formulas – Rule 5 For hydrates, that is, binary compounds with water (hydrate) attached: NiSO 4 ● 6 H 2 O a.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) sulfate hexahydrate

25 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.

26 Covalent Compounds Example: phosphate ion P O 4 3- Since oxygen is the more electronegative element, it will have its normal oxidation number Polyatomic ion with a charge = -3 Electronegativity:

27 Covalent Compounds Example: P O The phosphate ion has a charge of negative three, so the oxidation numbers must add up to the total charge of the ion

28 Ionic Compounds with Polyatomics Example: Ca SO 4 This is an ionic compound, so the charge of the metal cation is its oxidation number +2

29 Ionic Compounds with Polyatomics Example: Ca SO 4 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 +2

30 Ionic Compounds with Polyatomics Example: Ca SO 4 Oxygen is the more electronegative of the two, so it keeps its normal oxidation number

31 Ionic Compounds with Polyatomics Example: Ca SO 4 Sulfur and the four oxygen atoms must add to negative two (the charge of the sulfate anion)

32 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.

33 Ionic Compounds with Polyatomics Example: 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. +4

34 Ionic Compounds with Polyatomics Example: Pb(OH) 4 Within the anion, oxygen is the more electronegative of the two elements, and keeps its normal oxidation number

35 Ionic Compounds with Polyatomics Example: Pb(OH) 4 Within the hydroxide ion, the oxygen and hydrogen must add to the charge of the ion,


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