Chemical Nomenclature Formula Writing Naming Compounds Chemical Formula

Chemical Nomenclature: Formula Writing & Naming Compounds

Chemical Formula • The representation of a substance using symbols (letters) and subscripts (numbers) H 2 O 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. • Binary – 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 PO 5 • 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 – Tetra = four Di = two Penta = 5 Tri = three Hexa = 6

Practice Mono never STARTS a name! • Carbon dioxide • CO 2 • Dihydrogen monoxide • H 2 O • Sulfur hexafluoride • SF 6 • Phosphorous pentachloride • PCl 5

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

Ionic Names with Roman Numerals Copper II Chloride Copper II Chlorate 1. Write the symbols ( -ate is a polyatomic ion) 2. 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-

3. Make your charges cancel out 4. Write formula & reduce if you can • “ 1” doesn’t need to be written Cu. Cl 2 Cu(Cl. O 3)2

Practice • Lead II oxide • Pb. O • Lead IV oxide • Pb. O 2

Ionic Names without Roman Numerals Potassium Nitride Potassium Nitrate 1. Write down the symbols • If polyatomic ion look it up and write it in parenthesis. Don’t change it! 2. 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)

3. “Crisscross” 4. Write formula - REDUCE! • “ 1” doesn’t need to be written K 3 N KNO 3

Practice • Calcium Phosphate Ca 3(PO 4)2 • Magnesium Hydroxide Mg(OH)2

Formula Writing for 2 polyatomic ions Ammonium Phosphate 1. Write separate formulas in parenthesis – NEVER change what’s inside!!!!! 2. Assign charges 3. Make the charges cancel out with subscripts & write your final answer……. . (NH 4)3 PO 4

Practice • Ammonium Nitrate NH 4 NO 3 • Ammonium Hydroxide NH 4 OH

Naming……. .

Naming Binary Molecules. . . both elements are non-metals 1. 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

3. Write the name of the second element – end the name with • • hydrogen oxygen nitrogen sulfur fluorine chlorine bromine -ide hydride oxide nitride sulfide fluoride chloride bromide Practice • CO 2 carbon dioxide • N 2 O dinitrogen monoxide • SCl 5 sulfur pentachloride • H 2 O dihydrogen monoxide • CCl 4 carbon tetrachloride

Naming when the formula starts with a metal Mg. Cl 2 Fe. Cl 2 1. Name the first element 2. 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 • Cu. SO 4 Copper II sulfate • Ba(OH)2 Barium hydroxide • Al 2 S 3 aluminum sulfide • Cu. Cl copper I chloride • Cu. CO 3 copper II carbonate Remember: You only need a roman numeral if you have a transition metal, or Sn or Pb…. but not Zn or Ag

Naming polyatomic ion - element compounds NH 4 Cl 1. No prefixes 2. No roman numerals just name it! • Practice NH 4 F ammonium fluoride (NH 4)2 S ammonium sulfide

Naming compounds with 2 polyatomic ions • Just name them! Practice • (NH 4)2 SO 4 ammonium sulfate • (NH 4)2 Cr. O 4 ammonium chromate • (NH 4)3 PO 4 ammonium phosphate

The End