Presentation on theme: "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."— Presentation transcript:
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: 1. ____________________________________________ 2. ____________________________________________ 3. ____________________________________________ 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. PeriodPeriod 1 PeriodPeriod 1
More???? 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 Na 2 O.
Remember: the charges are written as superscripts (Na +1 ) and the counters in formulas are written as subscripts (Na 2 O). 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 Na 2 O 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 Draw a Lewis Dot structure for (p. 3 margin) FeO and Fe 2 O 3
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 K 2 O 1 or K 2 O Pb +4 O -2 -> Pb O -> Pb 2 O 4 simplifies to ______ PbO 2
So… Let’s look at the different combinations we can have… XY XY 2 XY 3
X2YX2Y X3YX3Y X3Y2X3Y2 X2Y3X2Y3 XY 2
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: Na 3 P: Li 2 O: PbCl 2 : sodium fluoride Aluminum nitride Silver bromide sodium phosphide Lithium oxide Lead (II) chloride
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 Ca +2 Zn +2 Be +2 K +1 Br -1 O -2 Cl -1 F -1 I -1 NaBr CaO ZnCl 2 BeF 2 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.
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 SnO 2. The charge on the tin makes a difference! If Fe 2 O 3 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 _____ III III IV V VI Cu 2 O Ni 2 O 3 FeI 2 Au 3 N PbO 2 Copper (I) oxide Nickel (III) sulfide Iron (II) iodide Gold (I) nitride Lead (IV) oxide
Going Backwards! Cu +1 CuF Cu +2 Au +3 Sn +4 Pb +2 F -1 Cl -1 O -2 P -3 CuCl 2 Au 2 O 3 SnO 2 Pb 3 P 2
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 Fe 2 O 3 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 is the only charge Silver Chloride Remember any element in Groups 1 & 2 have ONLY one Charge!! No Roman Numeral ever!!!
Silver chloride Lead (IV) oxide Tin (II) oxide Sodium phosphide Zinc bromide Iron (III) oxide Gold(III) iodide Chromium(III) Nitride Copper(II) oxide 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 acetate sulfate chlorate hydroxide NO 3 - ClO 2 - CrO 4 -2 SO 3 -2 PO 4 -3
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 NH 4 + 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: (NH 4 ) 2 O. To name compounds with polyatomic ions, use the name of the polyatomic ion listed on the reference table. Ex: (NH 4 ) 2 O is ammonium oxide; K 2 CO 3 is potassium carbonate. ternary ionic compounds: K 2 CO 3 and NaClO 4 binary ionic compounds: K 2 O and NaCl
Try your hand at these! KNO 3 Al(ClO 3 ) 3 SrSO 4 KNO 2 Mg 3 (PO 4 ) 2 Potassium nitrate Aluminum chlorate Strontium sulfate Potassium nitrite Magnesium phosphate
Going Backwards! ternary compounds Na +1 Ca +1 K +1 Au +3 NH 3 + OH - SO CrO CO ClO 4 - NaOH CaSO 4 K 2 CrO 4 Au 2 (CO 3 ) 3 NH 3 ClO 4
Ok…so how’d we do today 1. Cation:__Ag+1__Anion:___ (OH)-1____ Formula:___________________ Name:_____________________ 2. Cation:____ Fe +3 __Anion:___ (PO 4 ) -3 ___ Formula:___________________ Name:_____________________