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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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