Writing and Naming Ionic Formulas U7D2 Writing and Naming Ionic Formulas

U7D2: Writing and Naming Ionic Formula HW: WS: Formula Writing and Naming Practice Do Now: 1.HW out for check 2. Is [Cd]-2 the correct ion dot diagram for a Cadmium ion? Explain. Today: Review Naming Ionic Compounds Practice!!! TTL

The three steps in forming an ionic bond are: Metal loses e- to nonmetal becoming a cation. ____________________________________________ Nonmetal gains e- from metal to become an anion. Cation and anion attract to form an ionic compound. Period 1

Let’s practice

More???? Show me where you stand So.. Fist to Five Fist (not understanding need help) Five (feel I can teach it) Show me where you stand

Ionic Formula Writing The number of each type of ion that will form the new compound will depend on the size or magnitude of the charges (oxidation states). The charges must add up to zero. Ex. sodium reacts with chlorine, sodium forms a Na+1 ion & chlorine forms a Cl-1 ion. Only one of each ion is necessary -> the charges add up to zero: (+1) + (-1) =0 the formula of the new compound, sodium chloride, is simply NaCl.

but what if the charges aren’t equal and opposite? If sodium reacts with oxygen, sodium still forms a Na+1 ion but oxygen forms a O-2 ion. The new compound, sodium oxide, will require 2 Na+1 for every O-2: 2(+1) + (-2) =0 . The formula for sodium oxide is Na2O.

Remember: the charges are written as superscripts (Na+1) and the counters in formulas are written as subscripts (Na2O). Positive ions are written first and negative ions are written second in a formula. Lazy chemists do not bother to write 1 as counter in a formula. The element's symbol stands for the 1. Ionic formulas are always written in lowest terms. => an empirical formula. NaCl and Na2O are binary (2 element) ionic cds.

VI. DETERMINING CHARGES: The oxidation state or number is the charge or apparent charge an atom has in a compound. To determine the charge, simply look at the Periodic Table for the oxidation states of the element. For nonmetals it is the FIRST (top) oxidation state ONLY. For many metals, there is only one possibility for the charge. Transition metals and those metals close to the “crack”, there are more than one charge.

Look up the charges on the following: Remember to write the charges as superscript +2 +1 -1 -3 +1 -2 +2 +3 +1 +2 +3 -1 Draw a Lewis Dot structure for (p. 3 margin) FeO and Fe2O3

WRITING BINARY FORMULAS The ions of the elements combine in such a way that the charges have to add up to zero. Metal or positive ion (cation) is written FIRST Nonmetal or negative ion(anion)is written SECOND. The number one,1, is not written in the formula ex. NaCl.

Only the number in the charge for each ion is criss-crossed down and turned into subscripts. Always check that the formula is in LOWEST terms. K+1 O-2  K O  K2O1 or K2O Pb+4 O-2 -> Pb O -> Pb2O4 simplifies to ______ PbO2

So… Let’s look at the different combinations we can have… XY XY XY XY2 XY3

X2Y X3Y X3Y2 X2Y3 XY2

VII. NAMING The name of the positive ion is followed by the name of the negative ion. Group 1 & 2 Metals, Metals with ONE charge LISTED: name of the metal ONLY For nonmetals, the ending of the nonmetal’s name with the ending changed to IDE.

Let’s try! Name ionic compounds: NaF: AlN: AgBr: sodium fluoride Na3P: Li2O: PbCl2 : sodium fluoride Aluminum nitride Silver bromide sodium phosphide Lithium oxide Lead (II) chloride

Practice LiF Lithium fluoride AlCl3 Aluminum chloride SrS Strontium sulfide K3N Potassium nitride Mg3P2 Magnesium phosphide

How about backwards? Name -> formula Determine the elements involved, their charges & then write the formulas. Look up charges on the PT for the ions. Na+1 Br-1 NaBr Ca+2 O-2 CaO Zn+2 ZnCl2 Cl-1 F-1 Be+2 BeF2 K+1 I-1 KI

VIII. DETERMINING CHARGES AND NAMING of TRANSITION ELEMENTS Transition elements (metals) and some other metals located near the “crack”, can have more than one charge. Either you will be told which one to use or the charge can be determined from the formula. To distinguish between the different oxidation states or charges, a roman numeral equal to the charge on the ion is used to name the ion.

(Draw the Ion dot diagram for Iron (II) oxide) Ex, tin comes in two charges, +2 and +4. Sn+2 is called tin (II) and Sn+4 is called tin (IV). The formula of tin (II) oxide is SnO and the formula of tin (IV) oxide is SnO2. The charge on the tin makes a difference! If Fe2O3 is iron (III) oxide, what would be the formula for iron (II) oxide? _____ (Draw the Ion dot diagram for Iron (II) oxide) FeO

ROMAN NUMERALS: +1 ___, +2 ____, +3 ____, +4 ____, +5 ____, +6 _____ I II III IV V VI Cu2O Copper (I) oxide Ni2O3 Nickel (III) sulfide FeI2 Iron (II) iodide Au3N Gold (I) nitride PbO2 Lead (IV) oxide

Going Backwards! Cu+1 F-1 CuF Cu+2 Cl-1 CuCl2 Au+3 O-2 Au2O3 Sn+4 O-2 Pb+2 P-3 Pb3P2

Naming the Ionic Compounds from JUST the Formula Determine if it has a metal with more than 1 charge or not If yes, then look up the nonmetal’s charge and write the formula with each of the charges. Ex . FeO Fe+2 O-2  FeO Fe+3 O-2  Fe2O3 a) Since the formula with Fe+2 matches, FeO, then Fe+2 was used. Use the Roman numeral equal to this charge in the middle of the compound’s name. Iron (II) b) Change the name of the non-metal to the ending “ide”. Oxide Iron (II) Oxide If no, then just use the metal’s name and change the name of the non-metal to the ending “ide”. Ex. AgCl Ag+1 +1 is the only charge Silver Chloride Remember any element in Groups 1 & 2 have ONLY one Charge!! No Roman Numeral ever!!!

Silver chloride Iron (III) oxide Lead (IV) oxide Gold(III) iodide Tin (II) oxide Chromium(III) Nitride Sodium phosphide Copper(II) oxide Zinc bromide Calcium nitride

IX. POLYATOMIC IONS (PAI) A. Reference Table E Groups of atoms bond together by sharing electrons to form ions. one of the atoms in the group brings along a charge and group of atoms is not neutral “many atom” ion.

Complete this chart using reference table E. carbonate NO3 - acetate ClO2 - CrO4 -2 sulfate SO3 -2 chlorate PO4 -3 hydroxide

What type of charge do most of the PAI have? __________________ Most of these PAI end in _________ or __________ Two important exceptions are the positive ion _________ (ammonium) and the negative ion _________ (hydroxide). negative -ate -ite NH4 + OH-

B. Writing and Naming Compounds with Polyatomic Ions Rules: The formula must be in lowest terms the charges must add up to zero. Parenthesis are used around the polyatomic ion when more than one of these ions is necessary in a formula: (NH4)2O. To name compounds with polyatomic ions, use the name of the polyatomic ion listed on the reference table. Ex: (NH4)2O is ammonium oxide; K2CO3 is potassium carbonate. ternary ionic compounds: K2CO3 and NaClO4 binary ionic compounds: K2O and NaCl

Try your hand at these! KNO3 Potassium nitrate Al(ClO3)3 Aluminum chlorate SrSO4 Strontium sulfate KNO2 Potassium nitrite Mg3(PO4)2 Magnesium phosphate

Going Backwards! ternary compounds OH - NaOH Ca +1 SO2 -2 CaSO4 K +1 CrO4 -2 K2CrO4 Au +3 CO3 -2 Au2(CO3)3 NH3 + ClO4 - NH3ClO4

Ok…so how’d we do today Cation:__Ag+1__ Anion:___ (OH)-1____ 1. Cation:__Ag+1__ Anion:___ (OH)-1____ Formula:___________________ Name:_____________________ 2. Cation:____ Fe+3__ Anion:___ (PO4)-3___