binary ionic compounds. binary ionic compounds are made up of only two elements. the positive ion,...

Binary Ionic CompoundsBinary Ionic Compounds

Binary ionic compounds are Binary ionic compounds are made up of only two elements.made up of only two elements. The positive ion, or cation, is an ion consisting The positive ion, or cation, is an ion consisting

of only one atom. The name of this ion is the of only one atom. The name of this ion is the same as the name of the element. same as the name of the element. e.g. Ke.g. K++ is a potassium ion; Mg is a potassium ion; Mg2+2+ is a magnesium ion. is a magnesium ion.

The negative ion, or anion, is an ion consisting The negative ion, or anion, is an ion consisting of only one atom. The name of this ion is of only one atom. The name of this ion is formed by changing the ending of the element formed by changing the ending of the element to to –ide–ide. . e.g. Fe.g. F-- is a fluoride ion; O is a fluoride ion; O2-2- is an oxide ion. is an oxide ion.

For atoms in the s and p blocks, the For atoms in the s and p blocks, the charges of the ions may be determined charges of the ions may be determined from their position in the periodic from their position in the periodic table.table.

Transition elements can Transition elements can sometimes form cations with sometimes form cations with more than one charge.more than one charge. These cations are named by These cations are named by

including their charge as a Roman including their charge as a Roman numeral in parentheses.numeral in parentheses. e.g. Cue.g. Cu++ is the Copper (I) ion; is the Copper (I) ion; CuCu2+2+ is the Copper (II) ion. is the Copper (II) ion.

Cations and anions must be combined Cations and anions must be combined such that the total positive charges such that the total positive charges equal the total negative charges.equal the total negative charges.

Example: Potassium bromideExample: Potassium bromide K is found in the first column. Its charge K is found in the first column. Its charge

is therefore +1.is therefore +1. Bromine is found in Group 17. Bromine is found in Group 17.

Bromide’s charge is therefore -1.Bromide’s charge is therefore -1. To produce a neutral compound, one KTo produce a neutral compound, one K++

is needed for every one Bris needed for every one Br--. . Therefore the formula is KBr.Therefore the formula is KBr.


Example: Magnesium chlorideExample: Magnesium chloride Mg is found in the second column. Its Mg is found in the second column. Its

charge is therefore +2.charge is therefore +2. Chlorine is found in Group 17. Chlorine is found in Group 17.

Chloride’s charge is therefore -1.Chloride’s charge is therefore -1. To produce a neutral compound, one To produce a neutral compound, one

MgMg2+2+ is needed for every two Cl is needed for every two Cl--. . Therefore the formula is MgClTherefore the formula is MgCl22..


Example: Aluminum oxideExample: Aluminum oxide Al is found in the Group 13. Its charge is Al is found in the Group 13. Its charge is

therefore +3.therefore +3. Oxygen is found in Group 16. Oxide’s Oxygen is found in Group 16. Oxide’s

charge is therefore -2.charge is therefore -2. To produce a neutral compound, two To produce a neutral compound, two

AlAl3+3+ are needed for every three O are needed for every three O2-2-. . Therefore the formula is AlTherefore the formula is Al22OO33..

Transition elements can often have Transition elements can often have more than one charge. This charge more than one charge. This charge will be the same as the Roman will be the same as the Roman numeral.numeral.

Example: Iron (II) chlorideExample: Iron (II) chloride The iron ion has a charge of +2.The iron ion has a charge of +2. Chlorine is found in Group 17. Chlorine is found in Group 17.

Chloride’s charge is therefore -1. Chloride’s charge is therefore -1. To produce a neutral compound, one To produce a neutral compound, one

FeFe2+2+ is needed for every two Cl is needed for every two Cl--. . Therefore the formula is FeClTherefore the formula is FeCl22..

Naming binary compoundsNaming binary compounds

Name the ion with the cation first , the Name the ion with the cation first , the anion second. Examples:anion second. Examples: NaCl: Sodium chlorideNaCl: Sodium chloride MgClMgCl22: Magnesium chloride: Magnesium chloride CuClCuCl22: Copper (II) chloride: Copper (II) chloride FeFe22OO33: Iron (III) oxide: Iron (III) oxide

Note that the first word may or may not be Note that the first word may or may not be capitalized, but the second word (the capitalized, but the second word (the name of the anion) is name of the anion) is nevernever capitalized. capitalized.

For atoms that form more than one For atoms that form more than one ion, the Roman numeral indicating the ion, the Roman numeral indicating the charge must appear as part of the charge must appear as part of the name.name. Example: CuClExample: CuCl22

Cu can have more than one charge. Assume Cu can have more than one charge. Assume that this is true for any transition element.that this is true for any transition element.

Chlorine is in group 17, so the chloride ion Chlorine is in group 17, so the chloride ion must have a charge of -1.must have a charge of -1.

Since there are two ClSince there are two Cl- - for every one copper for every one copper ion, the copper ion must have a charge of +2.ion, the copper ion must have a charge of +2.

Therefore, the name is Copper (II) chloride.Therefore, the name is Copper (II) chloride.

For atoms that form more than one For atoms that form more than one ion, the Roman numeral indicating the ion, the Roman numeral indicating the

charge must appear as part of the charge must appear as part of the name.name.

Example: FeExample: Fe22OO33

Fe can have more than one charge. Assume Fe can have more than one charge. Assume that this is true for any transition element.that this is true for any transition element.

Oxygen is in group 16, so the oxide ion must Oxygen is in group 16, so the oxide ion must have a charge of -2.have a charge of -2.

Since there are three 0Since there are three 0-2 -2 for every two iron for every two iron ions, the iron ions must have a charge of +3.ions, the iron ions must have a charge of +3.

Therefore, the name is Iron (III) oxide.Therefore, the name is Iron (III) oxide.

binary ionic compounds. binary ionic compounds are made up of only two elements. the positive ion,...

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