Chemical Names and Formulas Chapter 9 Chemical Names and Formulas

Objectives for 9.1 (pgs 253-258) By the end of this section you WILL be able to… ID charges of monatomic ions by using PT Name ions Define polyatomic ion and write names and formulas of most common ones ID two common endings for the names of most polyatomic ions

Naming Ions Monatomic -Ions formed from a single atom -Charge determined by number of valence electrons NOTHING NEW! Cations -Positively charged -Form when elements LOSE electrons -Usually what type of elements?

Naming Cations -The name of the element followed by the word ion. -For example: Na+ is sodium ion, Mg2+ is Magnesium Ion Anions -Negatively charged -Form when elements GAIN electrons -Usually form from what type of elements?

Naming Anions -Named for the element but have the suffix –ide For Example: Cl- is chloride N3- is nitride

Ions of Transition Metals (p. 255) Since “s” and “d” valence electrons are available, transition metals may form cations with different charges (E.g. Fe2+ and Fe3+) Stock System of naming uses a Roman numeral to designate the charge on the ion -For Example: iron (II) and iron (III) – preferred over Classical naming system If the transition metal only forms one ion you do not have to use the stock system

Polyatomic Ions Ions that are made up of two or more covalently bonded atoms yet still have a net charge They behave like ions when bonding because of excess electrons, or excess protons To form some of these ions, BOTH electrons to be shared come from one atom What type of bond is this? -Coordinate Covalent

Oxyanions Most of the common polyatomic ions are oxyanions What do you think oxyanion means? -These anions contain different numbers of oxygen atoms We will use the suffixes –ite and –ate to show how many oxygen are on each

-ate indicates the ion with more oxygen atoms -ite indicates the ion with less oxygen atoms BFAt corner will help us identify how many oxygen If central atom is in the BFAt corner 3 oxygen atoms makes it an –ate 2 oxygen atoms is an –ite If central atom is out of the BFAt corner 4 oxygen atoms makes it an –ate and 3 oxygen atoms is an - ite

Practice naming these… SO42-, SO32-, NO2-, NO3-, F-, ClO2-, ClO3- Respectively, they are sulfate, sulfite, nitrite, nitrate, fluoride, chlorite, and chlorate You will need to memorize the charges!

Sometimes hydrogen appears at the beginning of an oxyanion This just changes the name to hydrogen ___ ate (or ite) For Example: HSO3 -2 is called hydrogen sulfite HSO4-2 is called________________

Prefixes The prefix hypo- means less (think hypothermia) This means there is one less oxygen than the oxyanion with the –ite ending. For example: ClO- is called hypochlorite SO2-2 would be called_________________

The prefix per- indicates that there is one MORE oxygen than the oxyanion with the –ate ending. For Example: ClO4- is called perchlorate PO53- is called _______________

Time to do work! Make flashcards for your polyatomic ions Memorize their charges Use the BFAt corner to determine if they are –ite or -ate End of section 9.1 What are your questions?

9.2 Naming and Writing Formulas Goals for this section…You will be able to… Apply the rules for naming and writing formulas for binary ionic compounds Apply the rules for naming and writing formulas for compounds with polyatomic Ions 9.2 Naming and Writing Formulas

9.2 Naming and Writing Formulas for Ionic Compounds Binary Compound -Compounds composed of two different types of elements Naming Binary Ionic Compounds Write the name of the cation Write the name of the anion For metals with more than one oxidation state, use the STOCK SYSTEM! For example: Iron (III) Chloride = FeCl3

Writing Formulas for Binary Ionic Compounds Ion Charge Method uses charges of ions to determine quantity of each ion in a compound The net charges of a compound = 0 Steps to writing balanced Formulas Write the symbol and charge for each ion present. Write the cation first then the anion. Examples: Na+ Cl- or Ca2+ Cl-

Adjust subscripts by using the cross-over method. Examples: Na+ Cl- or Ca2+ Cl- NaCl CaCl2 Reduce if necessary. Subscripts should be in simplest whole number ratio. 1 1 1 2

The cross-over method also works for polyatomic ions The cross-over method also works for polyatomic ions. However, you must place parentheses around the entire ion to signify more than one. Try these: Lead (II) Sulfate Barium Chloride Iron (II) acetate Ammonium Carbonate Tin (IV) chromate

PbSO4 BaCl2 Fe(C2H3O2)2 (NH4)2CO3 Sn2(CrO4)4 = Sn(CrO4)2 (lowest whole # ratio)

Compounds with Polyatomic Ions Write the symbol of the cation followed by the formula for the anion Cross over to balance charges Place parentheses around the polyatomic ion if there is more than one

Naming Compounds with Polyatomic Ions Memorize formula and charges of polyatomic ions (quiz is coming up) Name the cation (don’t forget about the stock system if needed) Name the anion Examples: A. Ca(OH)2 a. Calcium hydroxide B. FeSO4 b. Iron (II) sulfate

The reward of a thing well done is to have done it -Emerson 9.3 Naming and Writing Formulas for Molecular Compounds Interpret the prefixes in the names of molecular compounds in terms of their chemical formulas Apply the rules for naming and writing formulas for binary molecular compounds

Naming Binary Molecular Compounds Name the first element in the formula Use the appropriate prefix to show how many of that atom are present (see page 269) Name the second element Use the appropriate prefix to show how many of that atom are present Add the suffix –ide to show that it is a binary compound

Try these… N2O CCl4 CO Dinitrogen monoxide Carbon tetrachloride Carbon monoxide

Writing Formulas for Binary Molecular Compounds Use prefixes to tell you how many of each atom are present in the compound Dinitrogen tetroxide N2O4 Iodine heptafluoride IF7

9.4 Naming and Writing Formulas for Acids and Bases “If I set for myself a task, be it so trifling, I shall see it through. How else shall I have confidence in myself to do important things?” -George Clason Goals: Apply the rules for naming acids Apply the rules in reverse to write acids Apply the rules for naming bases

Acids and Bases Naming and Formula Writing -a substance that contains one or more hydrogen atoms and produces hydrogen ions (H+) when dissolved in water -The general form is HnX - The name is dependent upon the name of the anion

Rules! Rule 1 – if the anion ends in “-ide”, the acid name begins with “hydro” and ends with “-ic” (binary acid) (E.g. HCl = hydro-chlor-ic acid) Rule 2 – if the anion ends in “-ite”, the acid name ends with “-ous” (oxyacid). (no hydro) (E.g. H2SO3 = sulfur-ous acid)

Rule 3 - if the anion starts with “hypo” and ends with “-ite”, the acid name starts with “hypo” and ends with “-ous” (E.g. HClO = hypo-chlor-ous acid) Rule 4 – if the anion ends in “-ate”, the acid name ends with “-ic” (E.g. HNO3 = nitr-ic acid) Rule 5 - if the anion starts with “per” and ends with “- ate”, the acid name starts with “per” and ends with “- ic” (E.g. HClO4 = per-chlor-ic acid) I ate so much I felt icky

Naming Acids Use the same steps we did when writing formulas only backwards You should know your polyatomic Ions by now (they’re not going away)

Naming Bases Bases an ionic compound that produces hydroxide ions (OH-) when dissolved in water Naming Bases -Name bases as you would any other ionic compound

Laws of Definite and Multiple Proportions The Law of Definite Proportions - elements combine in a definite mass ratio regardless of the size of the sample produced (e.g. water is always 89% oxygen and 11% hydrogen by mass) The Law of Multiple Proportions – whenever the same two elements form more than one compound, the different masses of one element that combine with a fixed mass of the other element are in a ratio of small whole numbers Examples: H2O and H2O2 CO and CO2 N2O and N2O4

Classical Naming System Classical System of naming using the Latin name of the element and the suffix “-ous” to show the lower of two oxidation states (E.g. ferrous) The suffix “-ic” is used to show the higher of two oxidation states in the Classical System (E.g. ferric)