GC09 Naming and GC09 Naming and FormulasFormulas

Monatomic IonsMonatomic Ions

To name a Ionic Compound or determine it’s To name a Ionic Compound or determine it’s formula you need to understand how to identify formula you need to understand how to identify the number of electrons that are lost or gained in the number of electrons that are lost or gained in each atom.each atom.

CationsCations Atoms that lose electrons (becoming more positive)Atoms that lose electrons (becoming more positive)

• Lose 1 e-, atom becomes more positive by 1Lose 1 e-, atom becomes more positive by 1• Lose 2 e-, atom becomes more positive by 2Lose 2 e-, atom becomes more positive by 2

Metals in Groups 1A, 2A and 3A lose e- and form Metals in Groups 1A, 2A and 3A lose e- and form positive charges equal to their group numberpositive charges equal to their group number

Naming IonsNaming Ions

CationsCations The resulting name of the atom is the name of The resulting name of the atom is the name of

the element followed by either “ion” or “cation”the element followed by either “ion” or “cation”

Example: MagnesiumExample: Magnesium• Group 2: so 2 e- will be lost making the atom Group 2: so 2 e- will be lost making the atom

charge +2charge +2• This is written: MgThis is written: Mg+2+2

• The name is Magnesium ion or Magnesium cationThe name is Magnesium ion or Magnesium cation

Naming IonsNaming Ions

AnionsAnions When atoms gain electrons, they become more When atoms gain electrons, they become more

negative negative • Gain 1 e-: charge decreases to -1Gain 1 e-: charge decreases to -1• Gain 2 e-: charge decreases to -2Gain 2 e-: charge decreases to -2

The charge of any Group A non-metal is determined The charge of any Group A non-metal is determined by subtracting 8 from the group number.by subtracting 8 from the group number.

The name of an anion is not the same as the element The name of an anion is not the same as the element namename

• Start with the stem based on the element nameStart with the stem based on the element name• Add the suffix: “-ide”Add the suffix: “-ide”• Add “ion” or “anion”Add “ion” or “anion”

AnionsAnions

Example:Example: Selenium is a group 6A elementSelenium is a group 6A element

• It’s charge will be 6-8 = -2It’s charge will be 6-8 = -2• It name will be a combination of the element and “-It name will be a combination of the element and “-

ide”ide” Selenide ion or Selenide anionSelenide ion or Selenide anion Written as SeWritten as Se-2-2

Transition MetalsTransition Metals These metals consistently form +1, +2 or +3 cationsThese metals consistently form +1, +2 or +3 cations Many form MORE than one cationMany form MORE than one cation

The charge of a transition metal atom depends on the number of The charge of a transition metal atom depends on the number of electrons lostelectrons lost

Example: Iron (Fe)Example: Iron (Fe) If an iron atom loses 2 electrons, it will have a +2 chargeIf an iron atom loses 2 electrons, it will have a +2 charge It’s name will be “Iron (II) ion”, read “Iron two ion”It’s name will be “Iron (II) ion”, read “Iron two ion” It’s name is written as the symbol FeIt’s name is written as the symbol Fe+2+2

If an iron atom loses 3 electrons, it will have a +3 chargeIf an iron atom loses 3 electrons, it will have a +3 charge It’s name will be “Iron (III) ion”, read “Iron three ion”It’s name will be “Iron (III) ion”, read “Iron three ion” Its’ name is written as the symbol FeIts’ name is written as the symbol Fe+3+3

Transition metalsTransition metals

Try the following (Write out the name and Symbol):Try the following (Write out the name and Symbol): Cobalt (loses 3 e-)Cobalt (loses 3 e-) Nickel (loses 2 e-)Nickel (loses 2 e-) Copper (loses 1 e-)Copper (loses 1 e-) Copper (loses 2 e-)Copper (loses 2 e-) KK PP BeBe Zinc (loses 2-)Zinc (loses 2-) OO NaNa

Polyatomic IonsPolyatomic Ions

These are groups of atoms covalently bound These are groups of atoms covalently bound together, that have a positive or negative together, that have a positive or negative charge.charge.

Usually in the world we deal with polyatomic Usually in the world we deal with polyatomic ions.ions.

When you have a polyatomic ion, you deal with it When you have a polyatomic ion, you deal with it as a whole unit. You never mess with its as a whole unit. You never mess with its fundamental makeupfundamental makeup

Polyatomic IonsPolyatomic Ions You need to know these. The best way is to You need to know these. The best way is to

memorize them using flashcards.memorize them using flashcards.

Notice:Notice: ““-ite”-ite” “-ate”“-ate” SOSO33

-2-2 sulfite sulfite SOSO44-2-2 sulfate sulfate

NONO22-- nitrite nitrite NONO33

--, nitrate, nitrate ClOClO22

-- chlorite chlorite ClOClO33--, chlorate, chlorate

““ite” is used to indicate less oxygenite” is used to indicate less oxygen• How much less? You need to know!How much less? You need to know!

““ate” is used to indicate more oxygenate” is used to indicate more oxygen

Binary Ionic CompoundsBinary Ionic Compounds

Binary means “two”Binary means “two” Binary compounds are made up of two Binary compounds are made up of two

ions.ions.

To name any binary ionic compound, put To name any binary ionic compound, put the cation name first followed by the anion the cation name first followed by the anion name.name.

PracticePractice

CaI2CaI2 Na2ONa2O KClKCl NaClNaCl

A hard oneA hard one CuClCuCl CuCl2CuCl2

Calcium IodideCalcium Iodide Sodium OxideSodium Oxide Potassium ChloridePotassium Chloride Sodium ChlorideSodium Chloride

Copper (I) ChlorideCopper (I) Chloride Copper (II) ChlorideCopper (II) Chloride

Writing the Formula for Binary Ionic Writing the Formula for Binary Ionic CompoundsCompounds

This is the reverse of naming.This is the reverse of naming.

Say you have Ca and I. How do you know Say you have Ca and I. How do you know how many of each atom?how many of each atom?

First: Write the charges of each ion First: Write the charges of each ion (remember this is after the electron is lost/ (remember this is after the electron is lost/ gained).gained).

Writing Formulas: THE CRISS Writing Formulas: THE CRISS CROSS methodCROSS method

CaCa+2+2

gives 2 e-gives 2 e-

How do you know How do you know how many of each how many of each atom?atom?

CaICaI22

II--

Wants 1 e-Wants 1 e-

Use “criss cross”Use “criss cross”

Notice that the Notice that the resulting formula is resulting formula is electrically neutralelectrically neutral

PracticePractice

Use criss cross to determine the Use criss cross to determine the compound formulas for the following pairs compound formulas for the following pairs of elements, include the name:of elements, include the name:

Magnesium and FlourineMagnesium and Flourine Sodium and OxygenSodium and Oxygen Aluminum and BromineAluminum and Bromine Zinc (II) and ChlorineZinc (II) and Chlorine

Formulas and NamesFormulas and Names

MgF2, Magnesium Flouride

Na2O, Sodium Oxide

AlBr3, Aluminum Bromide

ZnClZnCl22, Zinc (II) Chloride, Zinc (II) Chloride