Chemical Nomenclature: Formula Writing & Naming Compounds

Chemical Formula The representation of a substance using symbols (letters) and subscripts (numbers) H2O The subscripts tell you how many atoms a compound is composed of. Water is made of 2 atoms of Hydrogen and 1 atom of oxygen

Writing Formulas for Binary Molecules aka Binary Covalent Compounds. made of 2 different elements Molecules are Covalently bonded together Both elements are non-metals To the right of the “staircase” AND Hydrogen

Ex. Phosphorus pentoxide PO5 Write the symbols for the elements in order ide refers to an element except peroxide & hydroxide Subscripts are written from prefixes and follow the symbol Mono = one Di = two Tri = three Tetra = four Penta = 5 Hexa = 6

Practice Carbon dioxide Dihydrogen monoxide Sulfur hexafluoride Mono never STARTS a name! Practice Carbon dioxide CO2 Dihydrogen monoxide H2O Sulfur hexafluoride SF6 Phosphorous pentachloride PCl5

Formula Writing for Ionic Compounds All ionic formulas are made of 2 parts A / B A is positive B is negative A can be: Metal or Polyatomic ion B can be: Non-Metal or Polyatomic ion

Ionic Names with Roman Numerals Copper II Chloride Copper II Chlorate Write the symbols ( -ate is a polyatomic ion) The positive oxidation state for the metal is given to you as a Roman Numeral You know the charge on the anion. It’s based on the number of valence e-

CuCl2 Cu(ClO3)2 Make your charges cancel out Write formula & reduce if you can “1” doesn’t need to be written CuCl2 Cu(ClO3)2

Practice Lead II oxide PbO Lead IV oxide PbO2

Ionic Names without Roman Numerals Potassium Nitride Potassium Nitrate Write down the symbols If polyatomic ion look it up and write it in parenthesis. Don’t change it! Assign oxidation states / charges Part A will be positive: you should know it! Part B will be negative and you should know them  or it’s a PAI (look it up)

K3N KNO3 “Crisscross” 4. Write formula - REDUCE! “1” doesn’t need to be written K3N KNO3

Practice Calcium Phosphate Ca3(PO4)2 Magnesium Hydroxide Mg(OH)2

Formula Writing for 2 polyatomic ions Ammonium Phosphate Write separate formulas in parenthesis NEVER change what’s inside!!!!!!!!!! Assign charges Make the charges cancel out with subscripts & write your final answer…….. (NH4)3PO4

Practice Ammonium Nitrate NH4NO3 Ammonium Hydroxide NH4OH

Naming……..

Naming Binary Molecules . . . both elements are non-metals Count the number of atoms as a prefix mono = one di = two tri = three tetra = four . . . 2. Write the prefix before the names of the elements Mono never STARTS a name

Write the name of the second element end the name with -ide hydrogen hydride oxygen oxide nitrogen nitride sulfur sulfide fluorine fluoride chlorine chloride bromine bromide Practice CO2 carbon dioxide N2O dinitrogen monoxide SCl5 sulfur pentachloride H2O dihydrogen monoxide CCl4 carbon tetrachloride

Naming when the formula starts with a metal MgCl2 FeCl2 Name the first element Check if this element is a transition metal or Tin or Lead no just name the second part yes assign the negative oxidation state first then determine the positive write it as a Roman Numeral

Practice CuSO4 Copper II sulfate Ba(OH)2 Barium hydroxide Remember: You only need a roman numeral if you have a transition metal, or Sn or Pb….but not Zn or Ag Practice CuSO4 Copper II sulfate Ba(OH)2 Barium hydroxide Al2S3 aluminum sulfide CuCl copper I chloride CuCO3 copper II carbonate

Naming polyatomic ion - element compounds NH4Cl No prefixes No roman numerals just name it! Practice NH4F ammonium fluoride (NH4)2S ammonium sulfide

Naming compounds with 2 polyatomic ions Just name them! Practice (NH4)2SO4 ammonium sulfate (NH4)2CrO4 ammonium chromate (NH4)3PO4 ammonium phosphate

The End