Naming of Ionic Compounds

Packet #15

Introduction

• An atom that has lost/gained electrons is considered to be an ion

• Cation

• Lost one or more electrons

• Positive charge

• Anion

• Gained one or more electrons

• Negative charge

NAMING IONS

Introduction

• Monatomic ion consist of a single atom with a positive or negative charge resulting from the loss or gain of one or more electrons.

NAMING IONS Anions

Introduction

• Remember, anions are formed when an atom gains one or more electrons while cations are formed when an atom has lost one or more electrons.

• The number of electrons added /lost determines what the charge the atom has.

Anions

• The charge of any ion of Group A nonmetal is determined by subtracting 8 from the group number.

Monatomic Anion—Naming

• The name of simple anions is obtained by adding –ide to the root of the atom name.

• Flourine

• F + e- = F-

• Flouride

• Bromine

• Br + e- = Br-

• Bromide

• Anions that have gained two electrons, oxide (O2-) and sulfide (S2-) for example, are named in the similar manner.

NAMING IONS Cations

Groups 1, 2 & 3

• When the metals in groups 1A, 2A and 3A lose electrons, they form cations with positive charges equal* to their group number.

• The metals of Group 1A, 2A and 3A consistently form cations of 1+, 2+ and 3+ respectively.

Monatomic Ion—Cation Naming

• Simple cations borrow their names from the names of the elements.

• K+ • Potassium ion

• Ca+ • Calcium ion

IONS OF TRANSITION METALS & METALS OF VARIABLE CHARGE

Ions of Transition Metals & Metals of Variable Charge

• Many of the transition atoms form more than one cation with different ionic charges.

• The charges of the cations of many transition atoms must be determined from the number of electrons that are lost.

Ions of Transition Metals & Metals of Variable Charge I

• The names of transition metals with two or more positive ions (cations) use a Roman numeral after the name of the metal to identify the ion charge.

• Iron

• Forms two common cations

• Fe2+

• Iron II ion

• Fe3+

• Iron III ion

• Tin, lead, copper, zinc and mercury

• Can also produce cations of different charges.

Naming Transition Elements Ions

• An older, useful method for naming cations, uses a root word with different suffixes at the end of the word.

• Ferrum is Latin for iron…therefore the root for iron is ferr-.

Naming of Transition Elements Ions II

• The suffix -ous is used to name the cation with the lower of the two cations.

• The suffix –ic is used to name the cation with the higher of the two cations. • Ferrous iron

• Fe2+

• Ferric iron

• Fe3+

Naming of Transition Elements Ions III

Naming of Transition Elements Ions IV

Naming of Transition Elements Ions V

Naming of Transition Elements Ions VI

POLYATOMIC IONS

Polyatomic Ions Introduction

• A polyatomic ion is composed of more than one atom.

• Polyatomic ions are tightly bound group of atoms that behave as a single unit and carry a charge.

Naming of Polyatomic Ions I

• The names of most polyatomic anions end in –ite or –ate.

• Discussion on how determine the endings found three slides ahead.

Naming of Polyatomic Ions II

• Sometimes the same two or three elements combine in different ratios to form a variation of a polyatomic ion. • Notice the endings

• Examine the charge

• Note the number of oxygen atoms that the ion contain.

• There should be a pattern.

Naming of Polyatomic Ions III

• The charge in each of the variations of the polyatomic ion in a given pair is the same. • The -ite ending indicates

the polyatomic with one less oxygen atom than the -ate ending.

Common Polyatomic Ions

SEE THE SPECIAL NOTE LOCATED AT THE BOTTOM OF THE SHEET.

IONIC COMPOUNDS

Introduction

• Ionic compounds, as previously mentioned, are composed of two parts • Cation

• Positive charge

• Anion

• Negative charge

• Special Note • The ionic compound may be composed of a cation that is

monoatomic or polyatomic AND/OR an anion that is monoatomic or polyatomic

System of Writing Formula of an Ionic Compound

• Write the symbol and charges for the cation and the anion

• Whether it is monoatomic or polyatomic

• Write the symbols for the ions side by side, beginning with the cation.

• Determine how to get a neutral compound

• Look for the lowest common multiple of the charges on the ions.

• For example, the lowest common multiple of 3 and 2 is 6.

• Fe3+

• Iron (III)

• O2-

• Oxide

• The lowest common multiple of 3 and 2 is 6.

• Therefore, the formula should indicate six positive charges and six negative charges.

• Fe2O3

• For 6 positive charges, you need two Fe2+

• For 6 negative charges, you need three O2-

System of Naming an Ionic Compound (Binary Ionic Compounds) Containing ONLY MONOATOMIC IONS I

• The name is made up of two words

• The name of the cation FOLLOWED by the name of the anion

• NaCl • Cation

• Sodium

• Anion

• Chloride

• Sodium chloride

• Al2S3 • Cation

• Aluminum

• Anion

• Sulfide

• Aluminum sulfide

System of Naming an Ionic Compound (Binary Ionic Compounds) Containing ONLY MONOATOMIC IONS II

• The name is made up of two words

• The name of the cation FOLLOWED by the name of the anion

• CuCl2

• Cation

• Copper (II)

• Anion

• Chloride

• Copper (II) chloride OR Cupric chloride

• Please remember the old system of naming ions that are variable (includes transition metals)

System of Naming an Ionic Compound (Binary Ionic Compounds) Containing ONE/MORE POLYATOMIC IONS I

• Determine whether the cation, and the anion, is monoatomic or polyatomic

• Name the cation

• Recall that if the cation is monoatomic and NOT a variable metal (transition metal), it is simply the name of the element

• Name the anion

• Remember, if the anion is polyatomic, AND contains oxygen, determine whether it receives–ite, –ate, hypo…–ite or per…–ate.

• K2CO3

• Cation • Potassium

• Anion • Has a charge of -2

• CO3-2 has a name of

carbonate

• The polyatomic ion’s name is thus potassium carbonate.

Special Note Naming Ionic Compounds WITH Variable Charge Metals {Transition Metals}

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