SIMPLY PUT, THE ART OF WRITING FORMULAS AND NAMING CHEMICALS

Writing Formulas Binary ionic compounds Ternary ionic compounds Binary molecular compounds Acids

Ionic Compounds Composed of oppositely charged ions Positive ion is a cation Negative ion is an anion Cations attract anions until the net (overall) charge on the formula unit is zero

Properties of Ionic Compounds Usually solid at room temperatureUsually solid at room temperature Are brittle and break under stressAre brittle and break under stress Usually soluble in water Conduct when melted or dissolvedConduct when melted or dissolved Have high melting points

Binary Ionic Compounds Contain a metal, written first, always positive, from left of stairs on the periodic table (it may sometimes have a roman numeral for its charge Contain a nonmetal, written second, always negative, from the right of stairs on the periodic table, ends in -ide The oppositely charged ions attract each other until the net charge is 0.

Binary Ionic Formulas Calcium oxide (metal / non-metal) Find calcium and its charge Ca +2 Find oxide and its charge O -2 To complete the formula, the charges must be completely balanced for a net charge of zero. Ca +2 O -2 The formula is: CaO

Another formula: Aluminum sulfide (metal / nonmetal) Find aluminum and its charge Al +3 Find sulfide and its charge S -2 To complete the formula, use the crisscross method and drop the signs: Al +3 S -2 The formula is: Al 2 S 3

Another one: Copper (II) nitride (roman numeral tells the charge!!!!!! It could be a +2 or a +1) So Cu +2 for the first ion And N -3 for the second ion Cu 3 N 2 is the resulting formula

Try these: Lithium sulfide Li 2 S Magnesium nitrideMg 3 N 2 Barium oxideBaO Copper (II) bromideCuBr 2 Manganese (IV) oxideMn 2 O 4 = MnO 2 Iron (III) chlorideFeCl 3 Calcium selenideCaSe

Ternary Ionic Compounds Consist of three or more elements. Contain at least one polyatomic ion which is a group of atoms with a charge such as sulfate, SO Polyatomic ions usually end in -ate, -ite and sometimes -ide as in cyanide and hydroxide and are on the back of the periodic table.

Ternary Ionic Formulas Lithium nitrate (metal / polyatomic ion) Find lithium and its charge Li +1 Find nitrate and its charge NO 3 -1 To complete the formula, the charges must be completely balanced for a net charge of zero. (criss-cross, drop +/-) The formula is: LiNO 3

Another formula: Calcium nitrate (metal / polyatomic ion) Find calcium and its charge Ca +2 Find nitrate and its charge NO 3 -1 To complete the formula, use the crisscross method and drop the signs. If the polyatomic ion has an added subscript, use parentheses around it. (NO 3 ) 2 The formula is: Ca(NO 3 ) 2

Try these: Potassium chlorateKClO 3 Strontium nitrateSr(NO 3 ) 2 Copper (II) sulfateCuSO 4 Rubidium phosphateRb 3 PO 4 Aluminum chromateAl 2 (CrO 4 ) 3 Iron (III) cyanideFe(CN) 3 Ammonium sulfide(NH 4 ) 2 S

Binary Molecular Compounds Contain two nonmetals Nonmetals are located to the right of the stairs on the periodic table They share electrons in a covalent bond to form molecules.

Properties of Molecular Compounds Usually gases at room temperature Are soft solids under stress Usually soluble in water Do not conduct when melted or dissolved Have low melting points

Binary Molecular Formulas Dinitrogen pentoxide (non-metal / non-metal) The prefix for each non-metal tells how many atoms of each element are present in the formula. It gives the subscript. “di” means a subscript of 2 after nitrogen N 2 “pent” means a subscript of 5 after oxygen O 5 The formula is: N 2 O 5

Try these: Dichlorine heptoxideCl 2 O 7 Diphosphorous trioxideP 2 O 3 Carbon tetrabromideCBr 4 Dinitrogen tetrahydrideN 2 H 4 Carbon disulfideCS 2 Boron trichlorideBCl 3

Naming Compounds These are the types: A)Binary Ionic Compounds  Metal with one possible charge  Metal with two or more possible charges B)Ternary Compounds C)Binary Molecular Compounds D)Acids

Binary Ionic Compounds (with fixed oxidation state on metal) the metal has one possible charge and is combined with a nonmetal Step #1: Name of Element with Positive Charge Step #2: Add Name of Negative element modifying ending to “ ide ”

Examples - Binary Ionic with one possible charge on the metal Al 2 S 3 aluminum sulfide CaBr 2 calcium bromide Mg 3 N 2 magnesium nitride NaCl sodium chloride

Binary Ionic Compounds (with variable oxidation state on the metal) the metal with several possible charges and is combined with a nonmetal Step #1: Name of Element with Positive Charge followed by the Roman numeral for its charge (I, II, III, IV, V, VI, VII, VIII, IX, X) Step #2: Add Name of Negative element modifying ending to “ ide ”

Examples - Binary Ionic with several possible charges on the metal CuCl 2 copper (II) chloride CuCl copper (I) chloride Fe 3 N 2 iron (II) nitride VBr 5 vanadium (V) bromide

Ternary Ionic Compounds Step #1: Write name of the ion having positive charge. If it is a metal, check to see if it has fixed or variable charge. If variable, it must have a roman numeral! Step #2: Add name of the negative polyatomic ion WITHOUT changing its ending.

Examples of Ternary Ionic Compounds Zn (NO 3 ) 2 zinc nitrate Cs C 2 H 3 O 2 cesium acetate Cr SO 4 chromium (II) sulfate NH 4 Cl ammonium chloride (NH 4 ) 2 SO 3 ammonium sulfite

Additional Examples – Roman Numerals Fe (ClO 3 ) 3 Iron (III) chlorate Cu(NO 3 ) 2 Copper (II) nitrate Mn SO 4 Manganese (II) sulfate

Review of all Ionic Compounds Name the following ionic compounds: BaS barium sulfide K 2 SO 4 potassium sulfate PbOlead (II) oxide Cu(NO 3 ) 2 copper (II) nitrate AlNaluminum nitride (NH 4 ) 2 CrO 4 ammonium chromate

Binary Molecular Compounds Consist of two nonmetals Write the name of the first element then the second element, changing its ending to –ide. Place prefixes in front of each element, indicating the number of atoms of each element in the formula. One exception, never use mono- in front of the name of first element. CO 2 CO carbon dioxide carbon monoxide

The list of prefixes is on the back of your periodic table!!! Check it out!

Examples of Binary Molecular CBr 4 carbon tetrabromide Cl 2 O 7 dichlorine heptoxide N 2 O 5 dinitrogen pentoxide

Formulas for Acids Hydrosulfuric acid (hydro- tells you it is binary!, sulf tells the second part) H +1 with S -2 and the formula is H 2 S Sulfuric acid ( ternary, no hydro, ic ending tells sulfate) H +1 and SO 4 -2 combine for H 2 SO 4 Sulfurous acid (ternary, no hydro, ous tells sulfite) H +1 and SO 3 -2 combine for H 2 SO 3

Properties of Acids Are corrosive - will cause burns React with metals Neutralize bases Dissolve in water Have a pH less than 7 on the pH scale Taste sour like a lemon

Try These! Hydrochloric acid __________________ Chloric acid__________________ Chlorous acid__________________ Hypochlorous acid__________________ Perchloric acid__________________

Naming Acids Acids start with hydrogen and are followed by an anion. Use the root of the anion and change it in the following manner: Anion ending “ide” start with “hydro” root of anion followed by “ic” acid HCl hydrochloric acid Anion ending “ate” start with root of anion, followed by “ic” acid HClO 3 chloric acid Anion ending “ite” start with root of anion, followed by “ous” acid HClO 2 chlorous acid

Examples of Naming Acids H 2 Sehydroselenic acid H 2 SO 3 sulfurous acid HNO 3 nitric acid

Examples of Naming Acids HBrhydrobromic acid HClO 4 perchloric acid HClOhypochlorous acid

Try These! H 2 S__________________ H 2 SO 4 __________________ H 2 SO 3 __________________

PROBLEM SOLVING In this chapter you will have to solve the following problems: 1.Find the percent composition of a material 2.Determine the empirical formula (simplest) 3.Determine the molecular formula (actual)

Acids: Know these!!!! HCl HNO 3 H 2 SO 4 H 3 PO 4