Nomenclature

Chemistry UnitScience 10

Nomenclature

• Ask yourself, “Is it binary or polyatomic?”

• If it is binary, it is made up of 2 elements (straight from the periodic table).

• Ex: LiF, HCl, MgO, Mg3N2 , AlH3

• Only 2 element symbols in the formula

Binary Compounds

• There are 2 types of binary compounds:

– Binary ionic (a metal and a non-metal)

– Binary covalent (2 non-metals)

Type 1: Binary Ionic• To name a binary ionic compound:

• the metal always comes first.

• the non-metal’s ending gets changed to ide.

• if it is a transition metal you need to decide which charge it is.

• balance of total negative and positive charge.

(2 elements, 1 metal, 1 non-metal)

Type 1: Binary Ionic• Going from formula to name is easy!

e.g. LiF: Lithium + Fluorine

Lithium Fluorine Lithium Fluor Lithium Fluoride

This compound’s name is Lithium Fluoride

(2 elements, 1 metal, 1 non-metal)

drop the non-metals ending and replace with the appropriate ending… which is?

…Write metal first, non-metal second

Type 1: Binary Ionic

• Going from name to formula requires you to balance the charges of your ions…

e.g. Beryllium Hydride: Beryllium + Hydrogen

So the formula would be BeH2

(2 elements, 1 metal, 1 non-metal)

Beryllium will give one of its electrons to the hydrogen, but it is still not balanced…

Now that all the elements are in their most stableforms (balanced), we can write the formula…

H ·· Be · · H

Type 1: Binary Ionic: Transition Metals

• Transition metals: Check your periodic table of ions to see what the charges of each Transition metal has.

• Balance charges on metal and non metal as per usual

(2 elements, 1 metal, 1 non-metal)

Type 1: Binary Ionic: Transition Metals

• Ex: Iron (II) sulphide Fe 2+ + S 2-

FeS

• Ex2: AuF3

So which gold will fit with our equation? Au(I) or Au(III) are the two different charges of gold

Will Au+ + F- or Au3+ + F+ give AuF3 - use your lewis transfer diagrams to decide

(2 elements, 1 metal, 1 non-metal)

Iron (II) has a 2+ charge whereas

Iron (III) has a 3+ charge

Au (I) has a 1+ charge whereas

Au (III) has a 3+ charge

THE ONLY DIFFERENCE WITH

TRANSITION METALS

TO OUR OTHER BINARY IONIC COMPOUNDS

IS THAT THEY CAN HAVE

MORE THAN 1 CHARGE

WE DO THEM THE EXACT SAME

Type 2: Binary Covalent

• To name a binary covalent compound:• use prefixes to indicate how many of each

there are.» Prefixes: mono, di, tri, tetra, penta, hexa,

hepta, octa, nona, deca.• also ends in ide.• balance using valence numbers (groups)

(2 elements, both non-metals)

Type 2: Binary Covalent

• To go from formula to name:

e.g. HCl - 1 Hydrogen, 1 Chlorine

The first element doesn’t get the mono prefix if it is just one. It does only if its more than one.

Hydrogen monochloride

(2 elements, both non-metals)

Type 2: Binary Covalent

e.g. N2O3 - 2 Nitrogen + 3 Oxygen

• prefixes: 2 nitrogen = di, 3 oxygen = tri• oxygen becomes oxide

So the name becomes: Dinitrogen trioxide

(2 elements, both non-metals)

Type 2: Binary Covalent

• Going from name to formula is just as easy with covalent compounds, since the name tells you how many of each you have

• e.g. nitrogen trichloride = NCl3 tetraphosphorus hexaoxide = P4O6

dinitrogen pentoxide = N2O5

sulfur hexafluoride = SF6

(2 elements, both non-metals)

It’s just that simple!!!

Polyatomic

• What does it mean to be polyatomic?More than 2 elements in a compound.

• You will find examples of these on the back of your periodic tables.

Naming Polyatomic Compounds

THEY ACT THE EXACT SAME AS YOUR BINARY IONIC COMPOUNDS

• these do not end in ide *most end in ate or ite.

• you decide on how many of each by balancing positive and negative charges (these compounds typically exist as ions)

the same as your binary ionic compounds are balanced

• if there is more than one of the polyatomic ion, it must be written in brackets with the subscript outside the bracket

• Polyatomic ions do not use prefixes

Naming Polyatomic Compounds

• e.g. Li2SO4

SO4 is an ion with a -2 charge, so it wants to gain two electrons to get its -2 charge. It will take one electrons from each of the 2 lithium allowing them to form an ionic bond.

• e.g. Ca(NO3)2 so we have 2 NO3’s

NO3 has a -1 charge, so it wants 1 electron, but calcium has 2 to give up so we need two NO3 to balance the formula.

Polyatomic Ions: the Ate or the Ite

• note that the ending of polyatomic ions depends on how many O’s there are

• more O’s is ate.• fewer O’s is ite.

• e.g. SO4-2 sulfate – 4 O’s

SO3

-2 sulfite – 3 O’s

Writing Polyatomic IonsGroup 17 (Halogens)

• these can all form 4 different ions when they bond with oxygen.

• named according to how many O…

FO FO2

FO3

FO4

}} ite because they have fewer O

ate because they have more O

Writing Polyatomic IonsGroup 17 (Halogens)

• these can all form 4 different ions when they bond with oxygen.

• named according to how many O…

FO > hypofluorite > even fewer OFO2 > fluorite

FO3 > fluorate FO4 > perfluorate > even more O

So what am I looking for?• When given a formula or name of a compound how will I

know if it is Binary Ionic, Binary Covalent, or Polyatomic?

• If the formula/name begins with a metal, you know right away that you are dealing with ions and must balance charges (Binary Ionic, or Polyatomic with metals).

• If you see prefixes like di or tri in the name you know it is Binary Covalent (since both ionic and polyatomic do not use prefixes)

• The first thing you should always check for is to see how many elements you have. If you have more than 2 elements, for the purposes of grade 10 science, you will be dealing with polyatomic ions.

Examples• Sodium phosphide

• We have a metal (Na+) and a non-metal (P3-).• So we need to balance the equation (Need 3 sodiums to

balance out the 3- charge of the P• so the formula becomes Na3P

• Dinitrogen pentoxide.• Due to prefixes, this is covalent so the formula is written

N2O5.

• Titanium (IV) bromate• Titanium (a metal) and bromate (a polyatomic)• Ti4+ and BrO3

- • Formula: Ti(BrO3)4