Formulas for Ionic Compounds

Ionic compounds are made up of a METAL and a NONMETAL and are generally referred to as SALTS.

Writing a Formula Problem: Write the formula for the ionic compound 1) Write the symbol for metal first first along with its combining capacity. 2) Write the symbol for the nonmetal with its combining capacity. 3) Goal is to BALANCE the charges. Use subscripts to indicate more than one atom.

Sodium and Chlorine

The goal is to balance the positive and negative charges to make a neutral compound Na + Cl - are the charges balanced? YES! So the formula is… NaCl

Bromine and Barium

What is the ionic formula for a compound of barium and bromine? Ba +2 Br - We need another Br – to balance the charges! Br - Thus, the formula is… BaBr 2

Write the formula for lithium with oxygen. Write the formula for magnesium with oxygen. Li + O -2 Li + = Li 2 O Mg +2 O -2 = MgO

Learning Check Write the correct formula for the compounds containing the following ions: A. Na +, S 2- 1) NaS 2) Na 2 S3) NaS 2 B. Al 3+, Cl - 1) AlCl 3 2) AlCl 3) Al 3 Cl C. Mg 2+, N 3- 1) MgN 2) Mg 2 N 3 3) Mg 3 N 2

Naming Binary Ionic Compounds Contain 2 different elements Name the metal first with its regular name, Change the nonmetal to–ide ending. Examples: 1)NaCl1) sodium chloride 2) ZnI 2 2) zinc iodide 3) Al 2 O 3 3) aluminum oxide

Learning Check Complete the names of the following binary compounds: Na 3 Nsodium ________________ KBrpotassium________________ Al 2 O 3 aluminum ________________ MgS_________________________

Solution Complete the names of the following binary compounds: Na 3 Nsodium nitride KBrpotassium bromide Al 2 O 3 aluminum oxide MgSmagnesium sulfide

Learning Check A. The formula for the ionic compound of Na + and O 2- is 1) NaO2) Na 2 O3) NaO 2 What is the name of the compound? B. The formula of a compound of aluminum and chlorine is 1) Al 3 Cl2) AlCl 2 3) AlCl 3 What is the name of the compound?

Solutions A. The formula for the ionic compound of Na + and O 2- is 2) Na 2 OThe name is sodium oxide B. The formula of a compound of aluminum and chlorine is 3) AlCl 3 The name is aluminum chloride

Transition Metals with More than One Combining Capacity If the metal has more than one combining capacity, the specific combining capacity being used must be given in the name as a ROMAN NUMERAL in brackets after the metal name. Copper can be Cu +1 or Cu +2 Iron can be Fe +2 or Fe +3 Lead can be Pb +2 or Pb +4 There are others as well…see the Per. Table or p. 341 in Hebden (Cations).

Naming Transition Metal Salts Use a roman numeral after the name of a transition metal that possesses multiple combining capacities FeCl 3 (Fe 3+ ) iron (III) chloride CuCl (Cu + ) copper (I) chloride SnF 4 (Sn 4+ ) tin (IV) fluoride PbCl 2 (Pb 2+ )lead (II) chloride Fe 2 S 3 (Fe 3+ )iron (III) sulfide

Learning Check Complete the names of the following binary compounds with variable metal ions: FeBr 2 iron (_____) bromide Cu 2 Ocopper (_____) oxide SnCl 4 ___(_____ ) ______________ Fe 2 O 3 ________________________ CuS________________________

Solutions Complete the names of the following binary compounds with variable metal ions: FeBr 2 iron ( II ) bromide Cu 2 Ocopper ( I ) oxide SnCl 4 tin (IV) chloride Fe 2 O 3 iron (III) oxide CuScopper (II) sulfide

Learning Check Name the following compounds: A. CaO - hint: does Ca have only one cc, or multiple cc? Do you need a roman numeral?? 1) calcium oxide2) calcium(I) oxide 3) calcium (II) oxide B. SnCl 4 1) tin tetrachloride2) tin(II) chloride 3) tin(IV) chloride C. Fe 2 O 3 1) iron oxide 2) iron (III) oxide 3) iron trioxide

Solutions Name the following compounds: A. CaO1) calcium oxide B. SnCl 4 3) tin(IV) chloride C.Fe 2 O 3 2) iron (III) oxide

Polyatomic Ions There are groups of atoms that tend to stay together (very stable) and carry an overall charge These groups are called polyatomic ions There is a list of polyatomic ions in the back of your Hebden text or on the back of your periodic table All polyatomic ions except ammonium NH 4 + have negative charges and act as nonmetals Notice that many have an –ate or –ite ending…this can alert you that you are dealing with a polyatomic ion

Homework IONIC NAMING WORKSHEET #1-33