Ch. 7-1a Naming Ions

POINT > Name and identify the charge of monatomic ions POINT > Define and determine formulas for binary compounds POINT > Define and name polyatomic ions

Metals in Groups 1A, 2A, 3A lose electrons forming (+) charged cations The ions lose the number of electrons needed to fulfill the octet rule (Noble gas config) The cation name is the same as the atom, followed by ion or cation (ex. Na + = sodium ion)

Lithium  Li + lithium ion Calcium  Aluminum  Potassium 

Nonmetals gain electrons forming (-) charged anions The ions gain the number of electrons needed to fulfill the octet rule (Noble gas config) The name of the anion is the stem of the element name, ending in -ide (ex. O 2- = oxide ion)

Chlorine  Cl - chloride ion Phosphorus  Sulfur  Nitrogen 

Many transition metals can form more than one cation, each having a different ionic charge Ex. Iron cation could be Fe 2+ or Fe 3+ Charge must be determined based on the name or formula of a compound (can’t just use group numbers…  )

Stock system for naming transition metal cations: Roman numerals after the name indicate the charge Ex. Iron: Fe 2+ written as iron(II) ion Fe 3+ written as iron (III) ion

Classical system for naming transition metal cations: Latin (or other) root/suffix indicates the charge: -ic refers to higher charge, -ous refers to lesser charge Ex. Iron: Fe 2+ written as ferrous ion Fe 3+ written as ferric ion

Binary compounds are composed of two elements Ex. H 2 O HCl CO 2 NaCl NH 3 If the compound is ionic, the cation is written first and the charges of the ions must be balanced

Ex. Determine the name and formula of a compound of iodine and magnesium Iodine ion is I - and magnesium ion is Mg 2+ Two I - are needed to balance with one Mg 2+ So formula unit would be MgI 2 = magnesium iodide

Determine the formula of a compound of: oxygen and potassium iron(II) and chlorine sulfur and copper(I) strontium and nitrogen bromine and lithium

What is the formula unit of: calcium flouride zirconium(I) carbide sodium sulfide aluminum oxide barium selenide

All of the examples you just encountered were ionic compounds. The charges in an ionic compound must balance, so naming them and determining formulas is straightforward… Atoms in a binary molecular compound can combine in different ways (ex. CO and CO 2, H 2 O and H 2 O 2 )

To name a binary molecular compound we use prefixes to denote the number of each type of atom in the compound Ex. CO 2 is carbon dioxide CO is carbon monoxide

Rules for naming binary molecular compounds: 1. Confirm two nonmetals 2. Name elements in the order of formula 3. Use prefixes to indicate numbers “mono” can be left out if it’s the first element, CO 2

Rules for naming binary molecular compounds: 4. Second element must end in –ide Ex. What is the name of N 2 Cl 5 ? dinitrogen pentachloride

Write the name of the molecular compound: CO SO 3 SO 2 N2S3N2S3 K3F2K3F2

To write the formula of a molecular compound, given the name, use the prefixes to identify the subscript of each element Ex. Hexasulfur tetrachloride would be… S 6 Cl 4 Remember: Molecular formulas do not get reduced, because they indicate the actual number of atoms present in the molecule

Write the formula of the molecular compound: Phosphorus trichloride Dinitrogen tetroxide Triselenium hexaflouride

Polyatomic ions are groups of atoms covalently bonded together that, as a whole, have a charge Ex. NO 3 - SO 3 2- PO 4 3- OH - NH 4 + These form ionic bonds with other ions: Ex. NaNO 3 MgSO 3 Li 3 PO 4 KOH NH 4 Cl

Most polyatomic ions are negatively charged and most contain oxygen Ex. NO 3 - SO 3 2- PO 4 3- OH - NH 4 + These form ionic bonds with other ions: Ex. NaNO 3 MgSO 3 Li 3 PO 4 KOH NH 4 Cl

Most polyatomic anions end in -ite or -ate -ite indicates fewer oxygen present -ate indicates more oxygen present Ex. SO 3 2- = sulfite ion SO 4 2- = sulfate ion ClO 2 - = chlorite ion ClO 3 - = chlorate ion

Sometimes there are more than two possible ions hypo- is added as prefix when fewer oxygen are present (-ite remains as suffix) ClO - Hypochlorite

Sometimes there are more than two possible ions per- is added as prefix when more oxygen are present (-ate remains as suffix) ClO 4 - Perchlorate

Note: Adding/removing oxygen does not change the charge of the polyatomic ion Sometimes a hydrogen is a part of the polyatomic ion. If so, the name includes hydrogen and the charge is reduced by 1 Ex. sulfate = SO 4 2- hydrogen sulfate = HSO 4 -

If a phosphate ion, PO 4 3- has a charge of 3- then the formula and charge of a phosphite ion would be a) PO 5 3- b) PO 4 2- c) PO 3 3- d) PO 3 2-

The atoms in a polyatomic ion are held together by a) ionic bonds b) covalent bonds c) intermolecular forces d) hydrogen bonding

If nitrate is NO 3 - what is nitrite? If sulfite is SO 3 2- what is sulfate?

 Read pages  Practice #1-2 page 211  Practice #1-2 page 213  Practice #1-2 page 215  Practice #1-2 page 217  F.A. #1-5 page 219