EXAMPLES. He VIA VIIA Li Be B C N O F Ne

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1 59 IA EXAMPLES VIIIA H IIA IIIA IVA VA He VIA VIIA Li Be B C N O F Ne Na Mg IIIB IVB VB Al Si P VIB VIIB VIIIB IB IIB S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Rf Db Sg Bh Hs Mt "inner" transition metals go here Find the formulas of: (1) an ionic compound containing Al and Br (2) an ionic compound containing Mg and O (3) an ionic compound containing S and K

2 60 Find the formula of: * an ionic compound containing Al and Br Find the formula of: * an ionic compound containing Mg and O Find the formula of: * an ionic compound containing S and K Reminder: When pairing ions to make an ionic compound, alwaly put the cation (+) first in the formula you write! >

3 61 IA H TRANSITION METAL IONS VIIIA IIA IIIA IVA VA He VIA VIIA Li Be B C N O F Ne Na Mg IIIB IVB VB Al Si P VIB VIIB VIIIB IB IIB S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Rf Db Sg Bh Hs Mt "inner" transition metals go here The transition metals always form CATIONS! However, many transition metals are capable of forming SEVERAL DIFFERENT CATIONS! Example: Iron (Fe) forms two cations, depending on the situation: Fe or Fe

4 62 TRANSITION METAL CATIONS - So how do you know which cation you're dealing with? For now, you'll have to be told - Either the chemical formula of an ionic compound or the name of an ionic compound can tell you what charge is on the transition metal cation. Examples: * The iron in this compound has a charge of +3. We call this kind of iron ion "iron(iii) ion"... pronounced "iron three ion". The compound is called "iron(iii) nitride". * The iron in this compound has a charge of +2. We call this kind of iron ion "iron(ii) ion"... pronounced "iron two ion". The compound is called "iron(ii) nitride".

5 63 POLYATOMIC IONS - Some MOLECULES can gain or lose electrons to form CATIONS or ANIONS. These are called POLYATOMIC IONS - Polyatomic ions form ionic compounds in the same way that single-element ions do. Example: CARBONATE ION * Use parenthesis when an ionic compound's formula contains more than one of a polyatomic ion. See the web site or Openstax page table 2.5 for a list of common polyatomic ions!

6 64 NAMES OF IONS - To properly discuss ions and ionic compounds, we have to know how to name them! CATIONS 3 kinds: Main group cations (metals that take only one charge when forming ions) - The element's name is the same as the ion's name! Mg : "magnesium ion" Transition metal cations (from metals that can form several cations) - The CHARGE of the cation must be given. Use a ROMAN NUMERAL after the element name to indicate charge! Polyatomic cations Fe Fe : "iron(ii) ion" : "Iron(III) ion" - Memorize list. NH : "ammonium ion"

7 65 ANIONS 2 kinds Main-group nonmetals - Use the STEM NAME of the element, then add "-ide" suffix N : "nitride" ion P : "phosphide ion" O : "oxide ion" F : "fluoride ion" Polyatomic ions - Memorize list.(see web site) C H O : "acetate ion" SO : "sulfate ion" NO : "nitrate ion" SO "sulfite ion" NO : "nitrite ion" * Polyatomic ions ending in "-ate" and "-ite" suffixes always contain oxygen! "-ate" ions have more oxygen atoms than their "-ite" counterparts.

8 66 NAMING IONIC COMPOUNDS - The name of the compound is based on the name of the ions in the compound - Cation first, anion second Examples: magnesium hydroxide iron(iii) oxide sodium sulfide copper(ii) oxide barium phosphate copper(i) oxide * Remember to include the Roman numeral for CHARGE when you're writing transition metal compound names! (See Openstax p 100 for a chart of polyatomic ions)

9 67 DETERMINING THE FORMULA OF AN IONIC COMPOUND FROM THE NAME - The name of an ionic compound is made of the names of the CATION and ANION in the compound. - To get the FORMULA, you must figure out the SMALLEST RATIO of cation to anion that makes the charges balance out Examples: iron(iii) carbonate potassium sulfide calcium bromide

10 68 DETERMINING IONIC FORMULAS tin(ii) phosphate chromium(iii) nitrate barium hydroxide titanium(iv) chloride Reminder: When indicating more than one of a polyatomic ion, enclose the ion's formula in parenthesis before adding the new subscript. Be particularly careful with HYDROXIDE, CYANIDE, and HYPOCHLORITE ions!

11 69 HYDRATES - many ionic compounds are formed by crystallizing the compound from water. Sometimes, this causes water molecules to become part of the crystal structure. - This water is present in a definite ratio to the ions in the compound. Can be removed by heating, but will NOT evaporate if the compound is left standing. # water molecules per formula unit of compound dot indicates that the water is weakly bound to the ionic compound - many DESSICANTS are hydrates that have had their water molecules driven off. They will slowly reabsorb water from the air (and keep the environment in a dessicator at a low humidity) - Hydrates are named using the name of the ionic compound, and a Greek prefix in front of the word "hydrate" to indicate how many water molecules are associated Why "copper(ii)"?

12 70 MOLECULAR COMPOUNDS - There are several kinds of molecular compound. We will learn to name two simple but important classes BINARY MOLECULAR COMPOUNDS - molecular compounds containing only two elements ACIDS - molecular compounds that dissolve in water to release H ions - corrosive to metals (react with many to produce hydrogen gas) - contact hazard: can cause chemical burns to eyes and skin - sour taste - turn litmus indicator RED - two kinds of acids: BINARY ACIDS - contain hydrogen and one other element OXYACIDS - contain hydrogen, OXYGEN, and another element

13 71 BINARY MOLECULAR COMPOUNDS - Named based on the elements they contain, plus prefixes to indicate the number of atoms of each element in each molecule FIRST ELEMENT - Add a GREEK PREFIX to the name of the element. - Omit the "MONO-" (1) prefix if there is only one atom of the first element SECOND ELEMENT - Add a GREEK PREFIX to the STEM NAME of the element - Add the suffix "-ide" (as if you were naming an anion) - DO NOT omit the "mono-" prefix if there is only one atom of the second element SEE COURSE WEB SITE FOR A LIST OF GREEK PREFIXES! THESE ARE THE SAME PREFIXES USED FOR THE HYDRATES!

14 72 BINARY MOLECULAR COMPOUNDS Examples: boron trifluoride dichlorine heptaoxide carbon monoxide carbon dioxide *Note: metalloids like boron behave chemically like nonmetals do. carbon tetrachloride dihydrogen monoxide dinitrogen tetrafluoride

15 73 BINARY ACIDS ACIDS - named after the element (other than hydrogen) they contain - common binary acids include a Group VIIA element - named: "Hydro-" + STEM NAME OF ELEMENT+ "-ic acid" Four common binary acids hydrofluoric acid hydrochloric acid dissolves glass! most common binary acid! hydrobromic acid hydroiodic acid

16 74 ACIDS OXYACIDS - Easy to think about as HYDROGEN IONS combined with POLYATOMIC IONS - These acids are not true ionic compounds, but they interact with water to PRODUCE ions! - named based on the polyatomic ion they contain, with an ending change: - ions ending in -ATE form acids ending in -IC - ions ending in -ITE form acids ending in -OUS sulfate phosphate sulfite nitrate sulfuric acid phosphoric acid sulfurous acid nitric acid

17 75 OXYACID EXAMPLES acetic acid nitrous acid carbonic acid The number of hydrogen atoms at the beginning of the formula equals the charge of the anion the acid is based on!