LECTURE 5 CHM 151 ©slg TOPICS: 1. Naming Cations 2. Naming Anions 3. Naming Ionic compounds 4. Naming Molecular Binary Compounds

NAMING MOLECULES AND COMPOUNDS There are many rules for naming many types of compounds: To name any compound, you must first recognize its “type.” “Guidelines”: If the compound formula starts with a nonmetal or metalloid,it is a molecular type compound If the formula starts with a metal, consider it an ionic compound, If the formula starts with H, it is an acid

We’ll name in this lesson two specific types: “binary molecules” (two non-metals in formula ) CO 2 PCl 3 SO 3 AsF 3 “ionic salts and bases” ( cation / anion combinations) cation: some metal ion or NH 4 + anion: OH - or O 2- (a “base”) all other anions: (“salts”) K 2 SO 4 NH 4 Cl NaOH MgO FeBr 3

Before naming ionic compounds, let’s review cations and anions, and examine charges and formulas we need to know.....

POSITIVE IONS: Cations CATIONS: positively charged ions; monoatomic cations are formed from metals which have LOST one or more electrons in compound formation: - 1 e Na (11p, 11e) > Na + (11p, 10e) (all Group 1A) -2e Ca (20p, 20e) > Ca 2+ (20p, 18e) (all Group 2A)

Metals Forming One Cation Only (Memorize!) Charge will be same as column or “Group Number” 3B elements form only one charge but aren’t on “memory list”

“One Charge Only”

Naming Cations: Fixed Charge Metals When the metal in the salt or base exhibits only one charge and forms only one cation, the name of the cation is identical with that of the metal: Na + sodium cation Mg 2+ magnesium cation Al 3+ aluminum cation Ag + silver cation

Metals Forming Several Cations All other common metals form cations resulting from the loss of a variable number of electrons (depending on the circumstances of the reaction). An examination of electronic structure (Unit 3) will justify all charges, single or multiple; now we simply must recognize “which is which”

Naturally Occurring, Non-Radioactive Metals

Common Metals, Fixed vs Variable Charge Metals which form single cation Metals which form several cations

Typically Encountered Cations, Variable Charge Metals Cr 2,3+ Fe 2,3+ Co 2,3+ Ni, Mn 2+ Cu 1,2+ Hg 2+, Hg 2 2+ Sn, Pb 2+ Bi 3+ Maximum (if not always common) charge on all metals is given by group number...

Naming Cations: Metals with Variable Charges When a metal is known to form several different cations of different charges, then the name of the cation must include a Roman Numeral indicating the charge of the ion: Fe 2+ Iron(II) cation Cu + Copper(I) cation Fe 3+ Iron(III) cation Cu 2+ Copper(II) cation Sn 2+ Tin(II) cation Bi 3+ Bismuth(III) cation

NEGATIVE IONS: Anions Monoatomic ANIONS: Single nonmetallic atoms which have gained one or more electrons in a chemical reaction and become negatively charged ions : +3e N (7p, 7e) > N 3- (7p, 10e) (all Group 5A) +2e O(8p, 8e) > O 2- (8p, 10e) (all Group 6A) +1e F (9p, 9e) > F 1- (9p, 10e) (all Group 7A)

3-3- Monoatomic Anions: Name, Charge Hydride Nitride Oxide Phosphide Sulfide Selenide Fluoride Chloride Bromide Iodide “ide”

FORMING IONIC COMPOUNDS Na + Cl - NaCl Na + S 2- Na 2 S Na + P 3- Na 3 P Ba 2+ Cl - BaCl 2 Ba 2+ S 2- BaS Ba 2+ P 3- Ba 3 P 2 Make sure charges balance; cross multiply when cation and anion charges are different:

GROUP WORK CATION, ANION Mg 2+ H - Fe 3+ S 2- Al 3+ P 3- Cd 2+ F - Mn 2+ I - FORMULA, NAME

POLYATOMIC IONS CATIONS: only one common, ammonium ion, NH 4 + ANIONS: negatively charged ions containing two or more elements; the knowledge of the formula and charge of the most common are basic to naming compounds and writing formulas. One of the elements usually involved is oxygen; the ion names end in “ate” or “ite” as follows...

Key Polyatomic Anion Formers: Know these! Br, I same as Cl Permanganate (7B) like Perchlorate Chromate (6B) like Sulfate

Polyatomic Anions of C, 4A Most common: CO 3 2- carbonate HCO 3 1- hydrogen carbonate, “bicarbonate” Others: CH 3 CO 2 - acetate (“C 2 H 3 O 2 - ”) CN - cyanide

Polyatomic Anions of N, P 5A Nitrogen: NO 3 - nitrate NO 2 - nitrite (Remember also: NH 4 +, ammonium; N 3-, nitride) Phosphorus: PO 4 3- phosphate HPO 4 2- hydrogen phosphate H 2 PO 4 1- dihydrogen phosphate (Remember also: P 3-, phosphide)

GROUP WORK CATION, ANION Cr 3+ CO 3 2- Ni 2+ CN - Zn 2+ NO 2 - Bi 3+ H 2 PO 4 - Pb 2+ N 3- FORMULA, NAME

Polyatomic Anions of O, S (6A) Cr (6B) Oxygen: OH - hydroxide Remember also: O 2- oxide Sulfur: SO 4 2- sulfate SO 3 2- sulfite HSO 4 - hydrogen sulfate HSO 3 - hydrogen sulfite Remember also: S 2-, sulfide Chromium: CrO 4 2- chromate

The “hydroxides” and “oxides” of the metallic elements are referred to as “bases”; all other ionic combinations are referred to as “salts” “BASES” and “SALTS” Bases: Mg(OH) 2 NaOH CaO Fe(OH) 3 Salts: MgCl 2 MgHSO 4 MgCO 3 Na 3 PO 4 NaNO 2 Na 2 SO 3 Ca(NO 3 ) 2 Ca 3 N 2 CaSO 4 Fe(CN) 2 Fe(CH 3 CO 2 ) 3 Fe(H 2 PO 4 ) 2

Polyatomic Anions of Cl, Br, I (7A) Mn (7B) Fluorine, F forms only the monatomic anion F - ; Bromine, Br and Iodine, I form the same ions as chlorine, Cl: Chlorine: ClO - hypochlorite ClO 2 - chlorite ClO 3 - chlorate ClO 4 - perchlorate Remember also: Cl -, Chloride Manganese: MnO 4 - permanganate

SUMMARY, NAMING IONIC SALTS AND BASES State name of the cation, then name of the anion. Cations with a variable charge are named by adding a Roman numeral Monoatomic anions are named by changing their elemental name to end in “ide” Polyatomic anions (memorized) end in “ite” or “ate”...

GROUP WORK FORMULA LiClO Cd(BrO 2 ) 2 Co(IO 3 ) 3 KMnO 4 Ag 2 CrO 4 NAME

Solutions FORMULA LiClO Cd(BrO 2 ) 2 Co(IO 3 ) 3 KMnO 4 Ag 2 CrO 4 NAME lithium hypochlorite cadmium bromite cobalt(III) iodate potassium permanganate silver chromate

Naming Binary Molecular Compounds All compounds beginning with a metal or ammonium are named as “ ionic compounds.” Compounds containing only two elements (“binary”) in which both elements in the formula are a non-metal or metalloid are named in a different manner... The change in nomenclature reflects the fact that these compounds are “molecular” and not “ionic” in nature!

Name the first element in the formula Name the second element in the formula to end in “ide”: carbide, nitride, phosphide, oxide, sulfide, fluoride, bromide, chloride, iodide Add numerical prefixes to indicate more than one atom of the element in the formula: di (2), tri (3), tetra (4), penta (5), hexa (6), hepta (7), octa(8) Binary Molecular Nomenclature Method:

Typical Nomenclature NO 2 SF 6 ICl 5 N 2 O 5 CBr 4 SO 3 P 2 O 3 nitrogen dioxide sulfur hexafluoride iodine pentachloride dinitrogen pentoxide carbon tetrabromide sulfur trioxide diphosphorus trioxide

BH 3 CH 4 SiH 4 NH 3 PH 3 borane methane* silane ammonia* phosphine COMMON NAMES, BINARY MOLECULES ENDING IN H