Symbol Name Symbol Name
H+ hydrogen ion H- hydride
Li+ lithium ion F- fluoride
Na+ sodium ion Cl- chloride
K+ potassium ion Br- bromide
Rb+ rubidium ion I- iodide
Cs+ cesiumion O2- oxide
Be2+ beryllium ion S2- sulfide
Mg2+ magnesium ion Se2- selenide
Ca2+ calcium ion Te2- telluride
Sr2+ strontium ion N3- nitride
Ba2+ barium ion P3- phosphide
Ra2+ radium ion As3- arsenide
Ag+ silver ion
Zn2+ zinc ion Al3+ aluminum ion
Note that the letters in an ion’s name before the -ideending is the stem.
For example, the stem for bromide is brom-. Also, just in case, the P for
phosphide is a capital P.
Symbols and Charges for Monoatomic Ions
Systematic nameCommon Systematic name Common
Symbol (Stock system) name Symbol (Stock system) name
Cu+ copper(I) cuprous Hg22+ mercury(I) mercurous
Cu2+ copper(II) cupric Hg2+ mercury(II) mercuric
Fe2+ iron(II) ferrous Pb2+ lead(II) plumbous
Fe3+ iron(III) ferric Pb4+ lead(IV) plumbic
Sn2+ tin(II) stannous Co2+ cobalt(II) cobaltous
Sn4+ tin(IV) stannic Co3+ cobalt(III) cobaltic
Cr2+ chromium(II) chromous Ni2+ nickel(II) nickelous
Cr3+ chromium(III) chromic Ni4+ nickel(IV) nickelic
Mn2+ manganese(II) manganous Au+ gold(I) aurous
Mn3+ manganese(III) manganic Au3+ gold(III) auric
Symbols and Charges for Polyatomic Ions
Formula Name Formula Name
NO3- nitrate ClO4- perchlorate
NO2- nitrite ClO3- chlorate
CrO42- chromate ClO2- chlorite
Cr2O72- dichromate ClO- hypochlorite
CN- cyanide IO4- periodate
MnO4- permanganate IO3- iodate
OH- hydroxide IO- hypoiodite
O22- peroxide BrO3- bromate
NH2- amide BrO- hypobromite
CO32- carbonate HCO3- hydrogen carbonate (bicarbonate)
SO42- sulfate HSO4- hydrogen sulfate (bisulfate)
SO32- sulfite HSO3- hydrogen sulfite (bisulfite)
C2O42- oxalate HC2O4- hydrogenoxalate (binoxalate)
PO43- phosphate HPO42- hydrogen phosphate
PO33- phosphite H2PO4- dihydrogen phosphate
S2O32- thiosulfate HS- hydrogen sulfide
AsO43- arsenate BO33- borate
SeO42- selenate B4O72- tetraborate
SiO32- silicate SiF62- hexafluorosilicate
C2H3O2- acetate (an alternate way to write acetate is CH3COO-)
There is one positive polyatomic ion. It is NH4+and is called the ammonium ion.
Note: Writing just the plus sign or minus sign for ions with +1 or -1 charges is
Binary Compounds of Metals with Fixed Charges
Given Formula, Write the Name
A binary compound is one made of two different elements. There can be one of each element such as in NaCl or KF. There can also be several of each element such as Na2O or AlBr3.
Please remember that all elements involved in this lesson have ONLY ONE charge. That includes BOTHthe cation AND the anion involved in the formula.
Points to remember about naming a compound from its formula
1. The order for names in a binary compound is first the cation, then the anion.
2. Use the name of cation with a fixed oxidation state directly from the periodic table.
3. The name of the anion will be made from the root of the element’s name plus the suffix “-ide.”
Example 1: Write the name of the following formula: H2S
Step #1 – Look at first element and name it. Result of this step = hydrogen.
Step #2 – Look at second element. Use root of its full name ( which is sulf-) plus the ending “-ide.” Result of this step = sulfide.
These two steps give the full name of H2S. Notice that the presence of the subscript is ignored. There are other types of binary compounds where you must pay attention to the subscript. Those compounds involve cations with variable charges. Your teacher will tell you which ones you will be held responsible for.
Example 2: Write the name of the following formula: NaCl
Step #1 – Look at first element and name it. Result of this step = sodium.
Step #2 – Look at second element. Use root of its full name ( which is chlor-) plus the ending “-ide.” Result of this step = chloride.
Example 3: Write the name of the following formula: MgBr2
Step #1 – Look at first element and name it. Result of this step = magnesium.
Step #2 – Look at second element. Use root of its full name ( which is brom-) plus the ending “-ide.” Result of this step = bromide.
Note the presence of the subscript does not play a role in this name.
Example 4: Write the name of the following formula: KCl
The first part of the name comes from the first element symbol: potassium. The second part of the name comes from the root of the second symbol plus ‘-ide,’ therefore chlor + ide = chloride.
This compound is named potassium chloride
Example 5: Write the name of the following formula: Na2S
First symbol is Na, so the first part of the name is sodium. (Note the presence of the subscript does not play a role in this name.) Second element is sulfur (from the symbol S), so the name is sulf + ide = sulfide.