Chemical Nomenclature Chemical Nomenclature is born with the publication of Méthode de nomenclature chimique The names proposed were based on the elements’ origin or function.

Chemical Nomenclature System for naming pure substances Element name used even if the substance is di- or polyatomic O 2 = oxygen S 8 = sulfur Compounds - naming differs depending on whether a substance is held together primarily by ionic or covalent bonds.

Metals and Non-metals For nomenclature purposes, metals are to the left of the stair step line and nonmetals are to the right.

Atoms Octet rule- – Electrons are arranged on levels or “shells”. Atoms are most stable with 8 electrons on their outermost shell (exception: H and He) Number of electrons on the outer shell = Same for all elements within each column of the s-block and p-block elements – Exception: Helium

Ions… To achieve the octet, atoms with more than 4 electrons on the outer shell will gain enough electrons to reach 8. Cl 7 electrons on outer shell Cl will gain 1 e -. Now #e - = 18 but #p + = 17 so the chlorine is an ion with the formula Cl 1-.

Ions… O 6 electrons on outer shell O will gain 2 e -. Now #e - = 10 but #p + = 8 so the oxygen is an ion with the formula O 2-. P 5 electrons on outer shell P will gain 3 e - Now #e - = 18 but #p + = 15 so the phosphorus is an ion with the formula P 3-

What Do We Call Them? Positive = cation To name the cation, we use the name of the element and simply add ion – Ex: Lithium Cation Negative = anion To name the anion, we change the ending of the element to ide. – Oxide – Chloride – Phosphide

Binary Ionic Compounds Cations (positively charged ions) and anions (negatively charged ions) will associate with each other and form a neutral binary compound to reduce energy. 1 Na + 1 Cl - NaCl 1 Ca 2+ 1 O 2- CaO 3 K + 1 N 3- K 3 N 2 Al 3+ 3 S 2- Al 2 S 3

Naming binary ionic compounds The name of the cation is the same as the name of the metal. Many metal names end in -ium. The name of the anion (negatively charged ion) takes the root of the nonmetal name and adds the suffix -ide. Calcium and oxygen form calcium oxide. Aluminum and sulfur form aluminum sulfide. The name of the cation (positively charged ion) is written first, followed by that of the anion.

Naming Ionic Binary Compounds

Naming Binary Ionic Compounds PROBLEM:Name the ionic compound formed from the following pairs of elements: PLAN: (a) magnesium and nitrogen SOLUTION: Use the periodic table to decide which element is the metal and which the nonmetal. The metal (cation) is named first and we use the -ide suffix on the nonmetal name root. (b) iodine and cadmium (c) strontium and fluorine(d) sulfur and potassium (a) magnesium nitride (b) cadmium iodide (c) strontium fluoride (d) potassium sulfide

Determining Formulas of Binary Ionic Compounds PROBLEM:Write simplest formulas for the compounds named in Sample Problem 2.5. PLAN: SOLUTION: Compounds are neutral. We find the smallest number of each ion which will produce a neutral formula. Place subscripts to the right of the element symbol. (a) Mg 2+ and N 3- ; three Mg 2+ (6+) and two N 3- (6-); Mg 3 N 2 (b) Cd 2+ and I - ; one Cd 2+ (2+) and two I - (2-); CdI 2 (c) Sr 2+ and F - ; one Sr 2+ (2+) and two F - (2-); SrF 2 (d) K + and S 2 - ; two K + (2+) and one S 2 - (2-); K 2 S

Binary Ionic Compounds The transition metal elements may form cations with more than one charge. To specify which cation forms a compound, a roman numeral equal to the charge is added to the cation name. Fe 2+ = iron (II) Fe 3+ = iron (III)

CHM 1010 PGCC Barbara Gage

Sample Problem 2.7Determining Names and Formulas of Ionic Compounds of Elements That Form More Than One Ion PLAN: SOLUTION: Compounds are neutral. We find the smallest number of each ion which will produce a neutral formula. Use subscripts to the right of the element symbol. PROBLEM:Give the systematic names for the formulas or the formulas for the names of the following compounds: (a) tin(II) fluoride(b) Cr I 3 (c) manganese (IV) sulfide(d) CrO 3 (a) Tin (II) is Sn 2+ ; fluoride is F - ; so the formula is SnF 2. (b) The anion I is iodide( I - ); 3I - means that Cr(chromium) is +3. Cr I 3 is chromium(III) iodide (c) Manganese (IV) is Mn 2+ ; oxide is S 2-, therefore the formula is MnS 2. (d) Cr is chromium; the anion O is oxide(2-); the compound is cobalt (VI) oxide.

Polyatomic Ions Some atoms form bonds that hold atoms together in a structure that has an overall charge (rather than as a neutral compound. These ions are called polyatomic ions. CO 3 2- carbonate SO 4 2- sulfate Compounds with polyatomic ions are named with the cation and anion name. Na 2 SO 4 – sodium sulfate

Determining Names and Formulas of Ionic Compounds Containing Polyatomic Ions PLAN: SOLUTION: Note that polyatomic ions have an overall charge so when writing a formula with more than one polyatomic unit, place the ion in a set of parentheses. PROBLEM:Give the systematic names or the formula or the formulas for the names of the following compounds: (a) Fe(ClO 4 ) 2 (b) sodium sulfite (a) ClO 4 - is perchlorate; iron must have a 2+ charge. This is iron(II) perchlorate. (b) The anion sulfite is SO 3 2- therefore you need 2 sodiums per sulfite. The formula is Na 2 SO 3.

Hydrates Some compounds have water molecules attached as part of their structure. These are termed hydrates. CuSO 4. 5H 2 O copper (II) sulfate pentahydrate Numerical Prefixes for Hydrates and Binary Covalent Compounds Number Prefix Number Prefix Number Prefix 1mono 2di 3tri 4tetra 5penta 6hexa 8octa 9nona 10deca

Binary Acids When certain binary gases dissolve in water they form acids with the same formula. The name is changed to add –ic acid to the anion HCl (g)  HCl (aq) hydrogen chloride hydrochloric acid

Binary Acids HF (aq)hydrofluoric acid HCl (aq)hydrochloric acid HBr (aq)hydrobromic acid HI (aq)hydroiodic acid HCN (aq)hydrocyanic acid

Oxyacids Acids containing oxygen; most do not exist in the same form without water HNO 3 nitric acid HNO 2 nitrous acid H 2 SO 4 sulfuric acid H 2 CO 3 carbonic acid H 3 PO 4 phosphoric acid HC 2 H 3 O 2 or CH 3 COOH acetic acid

Covalent Binary Compounds Non-metals form bonds by sharing electrons rather than transferring them. The resulting bond is referred to as a covalent bond. The element farthest to the left or lower on the periodic table is generally written first. Subscripts are replaced by numerical prefixes in the name.

Covalent Binary Compounds CO 2 carbon dioxide N 2 Odinitrogen oxide P 2 S 5 diphosphorus pentasulfide SiCl 4 silicon tetrachloride For many compounds where two vowels occur together when the prefix is added, the vowel from the prefix can be dropped (except for iodine). N 2 O 5 dinitrogen pentaoxide

Naming Binary Covalent Compounds

Determining Names and Formulas of Binary Covalent Compounds SOLUTION: PROBLEM:(a) What is the formula of carbon disulfide? (b) What is the name of PCl 5 ? (a) Carbon is C, sulfide is sulfur S and di-means 2 - CS 2. (b) P is phosphorus, Cl is chloride, the prefix for 5 is penta-. Phosphorus pentachloride.

CHM 1010 PGCC Barbara Gage