Naming and Formula Writing Practice, practice, practice

Compounds l Follow the Law of Definite Proportion. l Have a constant composition. l Two types: Ionic and Covalent (Molecular)

Chemical Formulas l Shows the kind and number of atoms in the smallest piece of a substance. l Molecular formula- number and kinds of atoms in a molecule. l CO 2 l C 6 H 12 O 6

Two Types of Compounds Ionic Compounds l Made of cations and anions. l Metals and nonmetals, generally l The electrons lost by the cation are gained by the anion. l The cation and anions surround each other. l Smallest piece is a FORMULA UNIT.

Naming Binary Ionic Compounds l Binary Compounds - 2 elements. l Ionic - a cation and an anion. l To write the names name the cation and change the suffix of the anion to -ide l Easy with Representative metals. l NaCl = Na + Cl - = sodium chloride l MgBr 2 = Mg +2 Br - = magnesium bromide

Naming Binary Ionic Compounds l Another step in the process comes with the transition metals. l Need to figure out their charges. l The compound must be neutral. (+ and – charges must add up to zero) In these cases- use the anion to determine the charge of the cation by doing some algebra

Naming Binary Ionic Compounds Example: name CuO (Cu has multiple oxidation states, so we must do some algebra) Need the charge of Cu, so look at O l O is -2, and there is one atom og O in the compound l copper must be +2 because there is only one atom of Cu, and the charges need to add to zero l Therefore, the answer is Copper (II) oxide l Name CoCl 3 l Cl is -1 and there are three of them = -3 l Co must be +3 Therefore, Cobalt (III) chloride

Naming Binary Ionic Compounds l Write the name of Cu 2 S. l Since S is -2, the Cu 2 must be +2, so each one is +1. Therefore, copper (I) sulfide l Fe 2 O 3 l Each O is -2 3 x -2 = -6 l 3 Fe must = +6, so each is +2. Therefore, iron (III) oxide

Naming Binary Ionic Compounds l Write the names of the following l KCl l Na 3 N l CrN l Sc 3 P 2 l PbO l PbO 2 l Na 2 Se

KEY l KCl potassium chloride l Na 3 N sodium nitride l CrN chromium (III) nitride l Sc 3 P 2 scandium phosphide l PbO lead (II) oxide l PbO 2 lead (IV) oxide l Na 2 Se sodium selenide

Ternary Ionic Compounds l Will have polyatomic ions l At least three elements l name the ions l NaNO 3 sodium nitrate l CaSO 4 calcium(II)sulfate l CuSO 3 copper (II) sulfite l (NH 4 ) 2 O ammonium oxide

Ternary Ionic Compounds l LiCN l Fe(OH) 3 l (NH 4 ) 2 CO 3 l NiPO 4

Ternary Compound Key l LiCN lithium cyanide l Fe(OH) 3 iron (III) hydroxide l (NH 4 ) 2 CO 3 ammonium carbonate l NiPO 4 nickel (III) phosphate

Writing Formulas l The algebraic sum of the charges must add up to zero. l Get charges on ions. l Cations from table or Table E l Anions from table or Table E. l Balance the charges by adding subscript, which act as multipliers for the charges l Put polyatomics in parenthesis if more than one

Writing Formulas l Write the formula for calcium chloride. l Calcium is Ca +2 l Chloride is Cl -1 l Ca +2 Cl -1 would have a +1 charge. l Need another Cl -1 l Ca +2 Cl 2 -1 the formula is CaCl 2

Write the formulas for these l Lithium sulfide l tin (II) oxide l tin (IV) oxide l Magnesium fluoride l Copper (II) sulfate l Iron (III) phosphide l gallium nitrate l Iron (III) sulfide

Key l Lithium sulfide LiS 2 l tin (II) oxide SnO l tin (IV) oxide SnO 2 l Magnesium fluoride MgF 2 l Copper (II) sulfate CuSO 4 l Iron (III) phosphide FeP l gallium nitrate Ga(NO 3 ) 3 l Iron (III) sulfide Fe 2 S 3

Write the formulas for these l Ammonium chloride l ammonium sulfide l barium nitrate

Key l Ammonium chloride NH 4 Cl l ammonium sulfide (NH 4 ) 2 S l barium nitrate Ba(NO 3 ) 2

Things to look for l If cations have (), the number indicated by the Roman numeral is their charge. l If anions end in -ide they are probably off the periodic table (Monoatomic) l If anion ends in -ate or -ite it is polyatomic – there are exceptions on Table E. Three of them end in –ide. Can you find them?

Part 2: Two Types of Compounds Molecular (Covalent) compounds l Made of molecules. l Made by joining nonmetal atoms together into molecules.

Molecular compounds l made of just nonmetals l smallest piece is a molecule l Molecular compounds name tells you the number of atoms. l Uses prefixes to tell you the number of each type of element

Prefixes l 1 mono- l 2 di- l 3 tri- l 4 tetra- l 5 penta- l 6 hexa- l 7 hepta- l 8 octa-

Prefixes l 9 nona- l 10 deca- l To write the name write two words

Prefixes l 9 nona- l 10 deca- l To write the name write two words PrefixnamePrefixname-ide

Prefixes l 9 nona- l 10 deca- l To write the name write two words l One exception is we don’t write mono- if there is only one of the first element. PrefixnamePrefixname-ide

Prefixes l 9 nona- l 10 deca- l To write the name write two words l One exception is we don’t write mono- if there is only one of the first element. l Be careful with double vowels- listen to the word when deciding whether or not to use it PrefixnamePrefixname-ide

Name These lN2OlN2O l NO 2 l Cl 2 O 7 l CBr 4 l CO 2

Key l N 2 O dinitrogen monoxide l NO 2 nitrogen dioxide l Cl 2 O 7 dichlorine heptoxide l CBr 4 carbon tetrabromide l CO 2 carbon dioxide

Write formulas for these l diphosphorus pentoxide l tetraiodide nonoxide l sulfur hexaflouride l nitrogen trioxide l Carbon tetrahydride l phosphorus trifluoride l aluminum chloride

Key l diphosphorus pentoxide P 2 O 5 l tetraiodide nonoxide I 4 O 9 l sulfur hexaflouride SF 6 l nitrogen trioxide NO 3 l Carbon tetrahydride CH 4 l phosphorus trifluoride PF 3

Two Types of Compounds Smallest piece Melting Point State Types of elements Formula UnitMolecule Metal and Nonmetal Nonmetals solid Solid, liquid or gas High >300ºCLow <300ºC IonicMolecular