Writing a formula for an Ionic Compound: 1st Write the symbols for the ions side by side (cation first): 2nd Cross over the charges : Al+3 O-2 3rd Check the subscripts (the smallest possible ratio of ions): Al+3 O-2 Al2O3 Al2O3

Practice: K+1 Br-1 ----------- Mg+2 Cl-1 ----------- Na+1 O-2 ------------ Mg+2 O-2 ----------- K+1 (NO3 )-1--------- Na+1 (SO4 )- 2--------- Pb+2 (NO3 )-1-------- Al+3 (SO4 )-2--------- KBr MgCl2 Na2O Mg2O2 MgO KNO3 Na2SO4 Pb (NO3)2 Al2(SO4)3

Writing names of ionic compounds: Write the name of the cation followed by the name of the anion: cation anion Element’s name Polyatomic Monatomic The suffix of the element name change by ide. See reference table (SO4 ) 2- -- sulfate. (NO3 ) 1- -- nitrate. Chlorine Chloride (NO2 ) 1- -- nitrite. Oxygen Oxide

Examples: MgCl2 Magnesium chloride Na3PO4 Sodium phosphate CaO Calcium oxide BaSO4 Barium sulfate

Writing names of ionic compounds: If the cation has more than one oxidation number, you must write it between parenthesis (using roman numeral): Examples: Fe2O3 Iron (III) oxide CuCl Copper (I) chloride

Practice: Write the name of the following: LiBr ----------- Aluminum fluoride --- MgO ---------- Ba(OH)2 ------- Sodium carbonate ------ Cu(NO3)2 ----- Iron (III) chloride ---------- NiSO4 --------- Sodium nitride ---------- Lithium bromide AlF3 Magnesium oxide Barium hydroxide Na2CO3 Copper (II) nitrate FeCl3 Nickel (II) sulfate Na3N

Binary Molecular Compounds: Compounds made by two different nonmetals. Examples: CO2 HBr P2O5

Naming Binary Molecular Compounds: 1)The first element in the formula is always named first, using the entire element name. 2) The second element in the formula is named using the root of the element & adding the suffix –ide. 3) Prefixes are used to indicate the number of atoms of each type that are present in the compound.

Prefixes # of atoms Mono ----------- one Di ---------------- two Tri --------------- three Tetra ----------- four Penta------------ five Hexa ------------- six Hepta –---------- seven Octa ------------- eight Nona ------------- nine Deca ------------- ten

Naming Binary Molecular Compounds: EXAMPLES: N2O5 – H2O -- N2O -- CO2 -- PCl5 -- SO3 -- NH3 -- dinitrogen pentoxide. dihydrogen monoxide. dinitrogen monoxide. carbon dioxide. phosphorus pentachloride. sulfur trioxide. nitrogen trihydride.

Writing Formulas (Molecular Compounds): 1) Write the element symbols in the same order than it appears in the compound name. 2) Use subscripts to represent the number of atoms of each element indicated by the prefixes used. Dinitrogen tetroxide ------ Dihydrogen monoxide ------ Diphosphorus monoxide ---- Carbon monoxide ------------ Phosphorus trichloride ----- N2O4 H2O P2O CO PCl3

Practice: 1) CCl4---- 2) Phosphorus tribromide –- 3) CO ----- 4) Dichlorine pentoxide ---- 5) HI(g) --- 6) Hydrogen chloride--- Carbon tetrachloride. PBr3 Carbon monoxide. Cl2O5 Hydrogen iodide. HCl(g)

II - Write the formulas of the following: Dinitrogen tetroxide ------ Dihydrogen monoxide ------ Diphosphorus monoxide ---- Carbon monoxide ------------ Phosphorus trichloride ----- III - Write the names or the formulas for: 1) CCl4---- 2) Phosphorus tribromide –- 3) CO ----- 4) Dichlorine pentoxide ---- 5) HI(g) --- 6) Hydrogen chloride---