Chapter 5: Nomenclature

Chemistry 1020: Interpretive chemistry

Andy Aspaas, Instructor

Binary ionic compounds

• Ionic compound: combination of metal cation and nonmetal anion

• Main-group metals in groups 1, 2, and 3– Form cations, charge can be predicted by group

number– Metal cations have the same name as the

element• Nonmetal: take root of element name and add -ide

– Charge predicted by taking 8 - group number• In naming compounds, cation is named first and

anion second

Ionic compounds with transition metal cations

• Transition metals can produce ions with varying charges

• When naming these compounds, you must indicate the charge of the cation in roman numerals after the cation name

– Ex. PbCl2 must have Pb2+ cations

– Name: lead(II) chloride

Compounds containing only nonmetals

• Binary compounds with only nonmetals are one type of molecules

• The first element given in the formula is named first, with its full name

• The second element is named as if it were an anion

• Use Greek prefixes to denote subscripts

– 1=mono, 2=di, 3=tri, 4=tetra, 5=penta, 6=hexa, 7=hepta, 8=octa

Polyatomic ions

• Polyatomic ion: a molecule (composed of 2 or more atoms) that carries a charge

• Oxyanion: one atom of a given element, bonded to different numbers of oxygen atoms.

– If there are 2 different oxyanions for a given element, use suffixes to differentiate their name

– “ite” for ion with fewer oxygens– “ate” for ion with greater number of oxygens

Polyatomic ions

Polyatomic ions

• Use prefixes if more than one oxyanion for an elementClO– hypochlorite

ClO2– chlorite

ClO3– chlorate

ClO4– perchlorate

• Oxyanions for a given element have the same charge, but added hydrogens decrease the charge

CO32– carbonate

HCO3– hydrogen carbonate, or bicarbonate

Nomenclature of compounds with polyatomic ions

• Type 1: Cation has known charge

– Use cation name and anion name

– Ex. Na2CO3, KH2PO4, NH4ClO3, Al2(SO3)3

• Type 2: Cation has several possible charges

– Use cation name and roman numeral for cation charge, then anion name

– Ex. CuSO4, Fe(CN)3, Ti(CrO4)2, Ag2SO3

Nomenclature of acids

• Acid: compound with one or more H+ ions attached to an anion

– Acids which do not contain oxygen• Name hydro ______ic acid (with element root in the

blank)

• HF, HCl, HBr, H2S

– Acids which contain oxygen• Use oxyanion name, but change suffix• “ite” becomes “ous”• “ate” becomes “ic”

• H2SO4, H2SO3, HNO2, H3PO4