Inorganic Nomenclature Naming Ionic Compounds and Writing Formulas

Chemical Names and Formulas In chemistry, chemical names and formulas are used interchangeably. You must learn how to shift back forth between them, if given a name, write a formula, and visa versa. We will start with the simplest inorganic compounds, binary salts.

Naming Binary Ionic Compounds Binary ionic compounds consist of a metal cation and a non-metal anion. The metal always comes first. The –ide suffix is added to the end of the non-metal. Sodium chloride Magnesium oxide Potassium sulfide Aluminum bromide

Given the formula, write the name 1) MgS 2) KBr 3) Ba3N2 4) Al2O3 5) NaI 6) SrF2

7) Li2S   8) RaCl2 9) CaO 10) AlP

Given the name, write the formula Look up the common ionic charge for the metal and non-metal on your reference table This is shown as “Selected Oxidation States,” in the top right hand corner of each element. Note that non-metals often have more than one oxidation state: ignore all but the top one for now.

Magnesium Oxide formula Look up oxidation states of Mg and O Write each as an cation and anion Mg2+ O2- Criss cross the charges, making them subscripts Mg2O2 Reduce by dividing by common denominator, if necessary MgO

Oxidation numbers without lookups

Names  Formulas 2) lithium bromide 3) calcium nitride 4) aluminum sulfide 5) potassium iodide 6) strontium chloride

7) sodium sulfide 8) radium bromide 9) magnesium sulfide 10) aluminum nitride 11) cesium sulfide 12) potassium chloride 13) strontium phosphide

Polyvalent Metals Many of the d-block metals (transition metals) are polyvalent: they have more than one type of ion. For example, iron: Fe2+ and Fe3+ There are two compounds of iron and oxygen: FeO and Fe2O3 Roman numerals are used to indicate the charge on the cation – they become iron (II) oxide and iron (III) oxide, respectively.

Tube Worms

Common Polyvalent Metals Fe Cu Sn Au Hg Pb Cr Mn Co

Rules for converting names to formulas Write ionic charges for polyvalent metal next to the symbol, look up oxidation number for the non-metal (always the negative one!) Criss-cross the charges to become subscripts; reduce to lowest common denominator (if necessary).

Names –> Formulas 1) iron(II) chloride 2) copper(I) sulfide 3) lead(IV) iodide 4) tin(II) fluoride 5) mercury(I) bromide 6) tin(II) oxide

Compounds with transition metals are often brightly colored, like FeCl3

7) chromium(III) oxide 8) gold(I) iodide 9) manganese(II) nitride 10) cobalt(III) phosphide 11) iron(III) chloride 12) copper(II) sulfide 13) lead(II) bromide

Rules for converting formulas to names Look up oxidation number of non-metal (always the negative one!) Count number of negative charges, divide by subscript of the metal Write I, II, III, etc. after the metal name, followed by the anion.

Formulas  Names 1) CuS 2) PbBr4 3) Pb3N2 4) Fe2O3 5) FeI2 6) Sn3P4

Cu2S SnCl2 HgO Hg2F2 CuCl2 CuBr PbO

Polyatomic Ions Many ions are actually made of two or more non-metals. Polyatomic ions have suffixes such as –ite, and –ate that you have heard throughout your lives. Reference Table E lists the more common polyatomic ions.

Calcite: a ternary ionic compound Calcite is an evaporite mineral found in dry lake beds The chemical name for calcite is calcium carbonate, or CaCO3

Potassium Permanganate What is the chemical formula?

K2Cr2O7 What is the name?

Ternary Ionic Compounds Compounds containing polyatomic ions commonly have three or more different elements These are called ternary ionic compounds. You will need to learn to recognize polyatomic ions in names and formulas, and go to your reference tables to make conversions Memorizing polyatomic names, formulas and charges is a good idea for future science majors

Names  Formulas 1) silver carbonate 2) potassium phosphate   2) potassium phosphate 3) aluminum hydroxide 4) sodium hydrogen carbonate 5) calcium acetate 6) potassium permanaganate 7) calcium perchlorate 8) lithium carbonate

Names  Formulas 9) magnesium hydrogen sulfite 10) sodium hypochlorite   10) sodium hypochlorite 11) tin(IV) chlorite 12) mercury(II) phosphate 13) tin(II) carbonate 14) mercury (I) acetate 15) lead(II) chromate 16) copper(I) sulfite 17) Tin (II) dichromate

Formulas  Names 1) AlPO4 2) KNO2 3) NaHCO3 4) CaCO3 5) Mg(OH)2   2) KNO2 3) NaHCO3 4) CaCO3 5) Mg(OH)2 6) Na2CrO4

7) Ba(CN)2 8) K2SO4 9) NaH2PO4 10) NH4NO3 11) Sn(NO3)2 12) FePO4 13) Cu2SO4 14) Ni(C2H3O2)2 15) HgCO3

All Types Together!! NaMnO4 PbSO4 AlBr3 NH4NO3 FePO4 Al2(SO4)3 KCN

Ammonium Nitrate: an ionic compound This very important compound is ionic, despite not having a single metal ion!!

The good and bad of NH4NO3

1 Chemical Name Chemical Formula 2 Ammonium sulfide   3 Ba(OH)2 4 Potassium phosphate 5 CrCl3 6 Mercury (II) nitrate 7 Cu2CO3 8 Sodium nitrite 9 Li2CrO4

10 Calcium hydrogen carbonate   11 HI 12 Lead (II) chlorite 13 HgO 14 Silver hypochlorite 15 CoSO4 16 Potassium cyanide 17 Sn3(PO4)4 18 Sodium hydroxide

19   NH4MnO4 20 Iron (III) sulfide 21 FeSO3 22 Mercury (I) chloride 23 ZnCl2 24 Sodium chlorate 25 K2Cr2O7 26 Ammonium phosphate 27 NaMnO4 28 PbSO4

KHCO3 Hg(OH)2 Sn(HCO3)4 NaH Fe(ClO4)3 Cu2CrO4

Iron (II) hydrogen sulfite Aluminum perchlorate Calcium chlorate Ammonium hydroxide Cobalt (II) iodide Iron (III) carbonate Iron (II) oxide Silver sulfide

Potassium nitrate   Potassium nitrite Ammonium chromate Lead (IV) chlorite Silver oxide Iron (III) hydrogen carbonate Barium hypochlorite Copper (I) carbonate

Chemical Name Chemical Formula Metals are always stated first, by using the name of the element. Metals first, non-metals second. Subscripts indicate the number of atoms of each element in the compounds. Non-metals are stated second. They always end with an –ide suffix (sodium choride) Parenthesis (often used for polyatomic ions) indicate that everything inside must be multiplied by the subscript. Ex: Ca(NO3)2 has 2 atoms of N and 6 of O. Metals with more than one valence are called polyvalent metals. The charge on the ion (always positive) can be found on the periodic table in the upper right corner of each element (oxidation numbers) Polyvalent metals must be recognized! The common ones are Fe, Co, Au, Pb, Sn, Cu, Mn, Cr, and Hg. The charge on the metal can be determined from the non-metal or polyatomic ion. Polyvalent metals are given Roman numerals to distinguish them from each other. (ex: Iron (II) and Iron (III)) Count the total number of negative charges (the charge on the ion * subscript on the ion) and divide by the number of atoms of the cation to get the charge on the cation. Polyatomic ions are made up of combinations of non-metals, and occasionally metals. The charges on the polyatomic ions are found on Table E. Polyatomic ions have unique names and charges. Many of them end in –ate or –ite suffixes. Most are negative ions. They can be found on Table E (front page) Polyatomic ions always have the same charge. Chemical names often must be converted into formulas. Here is a simple way to do this: Write the name of the metal, followed by the non-metal or polyatomic ion. Write the charge of the negative ion as a superscript to the right of the symbol. For non-metals, the charge is always the top oxidation number on the periodic table. Polyatomic charges must be looked up on Table E. Write the charge on the positive ion, given in the periodic table or in the chemical name Criss-cross the ionic charges; the anion supersript becomes the cation subscript; the cation charge becomes the number of anions. If necessary, reduce to lowest common denominator. Examples: CaCl2 chloride has –1 charge. Calcium is always +2. Write name: calcium chloride (no II necessary) Fe(NO3)3 NO3 is nitrate (Table E), w/ -1 charge Fe can be II or III. Which one? Since there are 3 nitrates, the charge on the Fe must be +3 Write the name: iron (III) nitrate. Ex. Barium Sulfate: Ba is +2; sulfate is SO42- from table E. Criss cross leaves Ba2(SO4)2 Reduce to lowest common denomentator: BaSO4. (NH4)2CO3 : Both of these ions are on Table E! NH4+ is ammonium; CO32- is carbonate; ammonium carbonate