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Chem I - Chemical Formulas and Nomenclature Name: ________________________ Period_____ I. Names of Elements The most common source for element names is a property of the elements. o EX: nitrogen: Greek for nitron (niter) and genes (to be born). Niter was the name for any naturally occurring substance that contained nitrogen. Some elements get their name from their place of discovery, person of honor, or from the mineral from which they are obtained. o Ex: Einsteinium or Berkelium II. Chemical Symbols Chemical symbols of the elements are shorthand of the elements. J. J. Berzelius, a Swedish chemist, is generally given credit for creating the modern symbols for the elements. Symbols correspond to the first letter of the name or the first two letters if needed to distinguish between elements with the same first letter. In some cases, the Latin form of the element was used. o EX: ________________is Fe for ferric All elements will begin with a capital letter. If there is a second letter, it is lowercase so that you differentiate between elements and compounds or molecules o EX: Cs = ________________ CS = ____________________ III. Chemical Formulas A chemical formula is a combination of symbols that represents the composition of a compound. Chemical symbols are used to indicate types of elements present. Subscripts are used to indicate the number of atoms for each element present. Coefficients are used to indicate the total number of molecules present. C8H18 2C8H18 _____ atoms of carbon _____ atoms of hydrogen Total # of atoms (_______) ________ atoms of carbon ________ atoms of hydrogen Total # of atoms (________) Oxidation Numbers of Monatomic Ions o The charge on a monatomic ion is the same thing as its oxidation number. o Because atoms want to reach an octet of valence electrons, the oxidation numbers, positive and negative charges, can be predicted for single atoms (__________________). o Metals tend to have positive oxidation numbers. (________________e-) o Nonmetals tend to have negative oxidation numbers. (_______________ e-) 1 Predicting Ionic Charges Group 1: Lose 1 electron to form 1+ ions H+ Li+ Na+ K+ Group 2: Loses 2 electrons to form 2+ ions Be2+ Ng2+ Ca2+ Sr2+ Ba2+ Group 13: Loses 3 electrons to form 3+ ions B3+ Al3+ Ga3+ Group 14: Lose 4 electrons or gain 4 electrons? ___________! Group 14 rarely form ions. Group 15: Gains 3 electrons to form 3- ions N3- (nitride) P3- (Phosphide) As3- (Arsenide) Group 16: Gains 2 electrons to form 2- ions O2- (Oxide) S2-(Sulfide) Se2-(Selenide) Group 17: Gains 1 electron to form 1- ions F1-(Fluoride) Br1- (Bromide) Cl1-(Chloride) I1-(Iodide) Group 18: Stable Noble gases ______________ form ions! Groups 3-12, Transition Elements: Some transition elements have only one possible oxidation state. o ______________= Zn2+ _____________= Ag+ Many transition elements have more than one possible oxidation state. o Iron(II) = Fe2+ Iron(III)= Fe3+ The oxidation number of a transition element can be determined by: o The Roman numeral indicating the oxidation. EX: iron (II) is Fe+2 iron (III) is Fe+3 Oxidation Numbers of Polyatomic Ions o ____________________ ions are ions that are made up of two or more atoms. o Refer to table of Polyatomic ions. o Polyatomic ions generally have the following endings: “ate” or “ite” o EX: (NO2)- _________________ (PO4)-3 _________________ Oxidation Numbers in a Compound o Compounds are formed by ions. _______________ + + Na + Cl- ______________ NaCl = Compound o A _________________ compound requires an equal number of positive and negative charges o The sum of the oxidation numbers in a compound must equal _______________. EX: EX: CaCl2 = 2 positive charges – 2 negative charges = 0 Ba+2 has an oxidation of +2, Cl- has an oxidation of -1 Therefore the formula would be: BaCl2 2 IV. Writing Ionic Formulas Remember: o Ionic compounds are composed of metals and nonmetals. o Ionic compounds are made from the gaining or losing of electrons and the resulting electrostatic force that holds the ions together. o The sum of the oxidation numbers in a compound must equal zero. o When writing formulas, the Cation (metal ion) is always written ___________ the Anion (nonmetal ion). o When using polyatomic ions, refer to the charge. There is only one polyatomic Cation: NH4+ that we will focus on. The remaining are polyatomic Anions. o You can determine the formulas of ionic compounds when given the only the name. EX: Sodium chloride Elements: sodium and chlorine Oxidation: +1 -1 # of each needed for 0 oxidation: 1 1 (+1 + -1 = 0) Formula: • ____________ EX: Magnesium Iodide Elements: Magnesium and Iodine Oxidation: +2 -1 # of each needed for 0 oxidation: 1 2 (+2 + -2 = 0) Formula: _________________ Now, let’s include polyatomic ions. EX: Sodium hydroxide Elements: Sodium (Na) and Hydroxide(OH) Oxidation: +1 -1 # of each needed For 0 oxidation: 1 1 ( +1 + -1 = 0) Formula: EX: Elements: Oxidation: # of each needed For 0 oxidation: Formula: ____________ Aluminum sulfate Aluminum(Al) and Sulfate(SO4) +3 -2 2 (+3 + +3 + -2 + -2 + -2) +6 + -6 = 0 ________________ 3 3 V. Criss Cross Method of Writing Formulas Notice a trend between the between the oxidation/charges of ions and the subscripts of elements. o EX: Mg+2 and Cl- gives ____________ o EX: Al+3 and SO4-2 gives _____________ This method crosses charges and subscripts to form neutral compounds. Draw the arrows showing the bonding below. o Ex: Al +3 and O-2 Al2O3 (neutral) o EX: Lead (II) phosphate Pb+2 and PO4 -3 Pb3(PO4)2 (neutral) Steps in using the Criss Cross Method of Writing Formulas 1. Write the oxidation numbers of each element or polyatomic ion. 2. Determine if the charges cancel each other, if so write the formula as a one-to-one ratio. o Na+ Cl- = ____________ o Ca+2 SO4-2 = ___________ 3. If the charges don’t cancel each other, apply the criss-cross method. o Na+ P-3 = __________ o Ca+2 PO4-3 = ______________ o Remember to put parenthesis around polyatomic ions if there will be more than one of them. Learning Check Circle the correct formula for the compounds containing the following ions: 1. Na+, S2a) NaS b) Na2S c) NaS2 2. Al3+, Cl-1 a) AlCl3 3. Mg2+, N3- a)MgN b)AlCl c) Al3Cl b)Mg2N3 c) Mg3N2 4 VI. Nomenclature Nomenclature is defined as a _________________ system. Chemistry uses nomenclature to standardize names of chemicals. VII. Naming Binary Ionic Compounds Naming binary (composed of _____________) ionic compounds. Name of cation is given first. The name of the cation is the same as the element. Name of anion is given last. The name of the anion is the same as the element, but with an “____________” suffix. EX: Al2O3 Aluminum and Oxygen _______________ cation anion Naming Ionic Compounds containing Transition Metals o If the cation is a transition metal, such as _________(Sn) and ____________(Pb), it can have more than one oxidation number. o So, figure out the cation’s charge and use the roman numerals. o Make sure to put the roman numerals in parenthesis after the name of the cation. EX: Pb+2 = ____________(II) Sn+4 = ____________(IV) Cu+1 = _____________(I) Transition Metals with One Oxidation o We only use the Roman Numeral System for those metals with more than one _____________. o Transition elements with only one possible oxidation will be named with the name of the metal only. _____________ (can only be +2) _____________ (+1) _____________ (+2) Naming Ionic Compounds – Learning Check EX: _______________ is Silver Chloride ______________ is Zinc oxide _______________ is Calcium bromide _______________ is Sodium oxide 5 Naming Ternary Ionic Compounds o Ternary Compounds contain a ______________________ ion. 1. Write name of cation as it is on the periodic table (or poly-ion sheet) 2. Write the name of the poly-ion as it’s written on the sheet – don’t change the ending. o EX: Al2(SO4)3 = _______________________ o EX: Mg(OH)2 = _______________________ Naming Ionic Compounds – Learning Check o Li2CO3 _________________ o FeO is ________________ o Ba(OH)2 ________________ o Sn(NO3)4 ______________ o Zn(NO3)2 _______________ o CuCl _________________ o KClO3 is _________________ o MnSO4 __________________ VII. Writing/Naming Molecules Remember: o Molecules are substances that are covalently bonded together. They contain a nonmetal bonded to a nonmetal o How can you tell the difference between a polyatomic ion and a molecule? Poly-ions have a charge when not bonded to a metal – ex. (PO4)3- or K3PO4 Molecules contain only nonmetals and __________ overall charge – ex. P2O3 In order to be effective in naming molecules, these prefixes must be committed to memory: 1. Mono- Molecular Prefixes 6. hexa- 2. Di- 7. hepta- 3. Tri4. Tetra- 8. octa9. Nona- 5. Penta- 10. Deca- 6 To name binary molecules, follow these rules: 1. The less __________________ element is given first. It is given a prefix if it contributes more than one atom to the molecule. 2. The second element is named by combining a. (a) a prefix indicating the number of atoms contributed by the element, b. (b) the root of the name of the second element, and, c. (c) the ending ____________. 3. The ________ or ________ at the end of a prefix is usually dropped when the word following the prefix begins with another vowel. EX: _______________ or ______________ instead of monooxide or pentaoxide EX: P4O10 o P is less e-neg and it has more than one atom in this molecule. _____________________ o O is named by combining prefix, root name, and ide ending. ____________________ (a is dropped from prefix) *combine to form: Tetraphosphorus decoxide Naming Binary Molecules – Learning Check EX: SO3 is _________________ ICl3 is ____________________ PBr5 is ________________________ H20 is ____________________ Writing Binary Molecules Now… let’s look at writing the molecular formula from the name. When writing the formula of a molecule, an atom’s prefix is its subscript. Do not cross anything. When there is only one of the first atom, a prefix is __________________ o Example #1 Sulfur trioxide = _____________ o Example #2 dichlorine heptaoxide = ________________ o Example #3 phosphorus pentachloride = _______________ o Example #4 dinitrogen monoxide = __________________ 7 o Example #5 carbon monoxide = _________________ o Example #6 dinitrogen trisulfide = _______________ VIII: Writing/Naming Acids Acids are molecular compounds that contain ______________ bonded to a nonmetal or to a group of polyatomic. Acids can be either _____________or ________________ compounds. o Names of binary acids have the form Hydro-_______ acid o Names of ternary acids use a series of prefixes and suffixes to specify the number of oxygen atoms in the molecule. Naming Binary Acids EX: Binary acid: Try: HF is ____________________________ HCl is ___________________________ H2S _____________________ HI _____________________ HBr _____________________ Remember this! It helps Naming Ternary Acids o o o When naming ternary acids, identify polyatomic ion in the formula. For polyions that end in “_____” change the ending to “_____”. (Something I “ate” made me feel “ic”). For polyions that end in “_____” change the ending to “______”.(A snake b“ite” is poison“ous”) EX: nitrate _________________ nitrite _________________ sulfite _________________ sulfate __________________ Naming Ternary Acids with four Oxygen Possibilities o o o Some ternary acids have more than one oxygen possibilitiy. When naming ternary acidse from plyions that have up to four oxygen possibilities: For polyions that end in “_____” change the ending to “______”.(A snake b“ite” is poison“ous”) -ic greatest # of oxygen atoms. -ic greater # of oxygen atoms. -ous smaller # of oxygen atoms. -ous smallest # of oxygen atoms. *Know all form of ClO3-1and IO3-1 8 Polyion Acid Formula Acid Name ClO4-1 HClO4 perchloric acid ClO3-1 HClO3 chloric acid ClO2-1 HClO2 chlorous acid ClO-1 HClO hypochlorous acid o Name the following ternary acids having more four oxygen possibilities HIO ____________________ HIO3 __________________ HIO2 ____________________ HIO4 __________________ Naming Acids – Learning Check HCl = ____________________ HF _______________________ H2SO4 ____________________ HNO3 ____________________ H3PO4 ____________________ HNO2 ____________________ Writing Formulas of Acids Acids are molecules that are covalently bonded, yet they have properties of ionic compounds, so use rules for creating neutral ionic compounds. Formulas for acids begin with hydrogen. The oxidation state for hydrogen is +1. Identify if the acid is binary or ternary. If the acid is binary, it will have a “______________” prefix, all others will be ternary. 1. Formulas of Binary Acids Write H+ Identify the monotomic anion by its root name in the acid. Determine its charge by following the oxidation trend for the groups. Write the element symbol and its negative oxidation. Cris cross charges to create neutral acid formulas. EX: hydrosulfuric acid = ______________________ Now Try: hydrochloric acid = H+ + Cl- = ___________ hydrophosphoric acid = H+ +P-3= __________ hydrobromic acid = H+ + Br- = ___________ hydrofluoric acid = H+ + F- = _____________ 2. Formulas of Ternary Acids Write H+ Identify polyion by: 1. Ic _________ and ous __________ suffixes 2. Prefixes of per and hypo to indicate numbers of oxygen atoms for chlorates and iodates Write formula of polyion including oxidation. 9 Criss cross charges for neutral formula. EX: sulfuric acid = ______________________ Now try: phosphoric acid = (ate to ic) nitric acid =(ate to ic) H+ + PO4-3 = ____________ H+ + NO3- =___________ nitrous acid = (ite to ous) sulfurous acid = (ite to ous) H+ + NO2- = ____________ H+ + SO3-2 = ___________ perchloric acid = (ate to ic) hypoiodous acids= H+ + ClO4- =____________ H+ + IO-= _____________ acetic acid = (ate to ic) H+ +C2H3O2 =___________ 10 Naming Compounds Flow Chart Does the Formula begin with H? NO YES Does it begin with a metal which has more than one oxidation number? (eg Fe, Ni, Cu, Sn, Hg) NO YES It is an Acid (must be aqueous) Does the acid contain a polyatomic ion? YES NO Name the first element followed by its oxidation numbers (Roman numeral) Ending of polyatomic ion -ate Does the formula contain a polyatomic ion? NO YES Are both elements nonmetals? NO YES Name the first element, then the second element with the – ide ending. -ite Name the polyatomic ion, replacing the –ate ending with -ic. Add the word acid. Name the polyatomic ion, replacing the –ite ending with -ous. Add the word acid. Name the first element using the proper prefix. (never mono-). Name the second element with the proper prefix (including mono- and – ide ending.) 1 mono2 di3 tri4 tetra5 penta6 hexa7 hepta8 octa9 nano10 deca- Write the prefix hydro, then the name of the second element with –ic ending. Add the word acid. Name the first element, then the polyatomic ion. If two elements are present, name both, then the polyatomic ion. (e.g. NaHCO3 is sodium hydrogen carbonate) 11 Common Polyatomic Ions ANIONS: 1* Acetate 2C2H3O2− NH2− N3− C7H5O2− BrO3− ClO3− ClO2− OCN− Amide Azide Benzoate Bromate * Chlorate * Chlorite Cyanate * Cyanide * * * * * * * Dihydrogen phosphate Formate Bicarbonate Bisulfate Bisulfide Hydroxide Hypochlorite Iodate Nitrate Nitrite Perchlorate Permanganate Thiocyanate Triiodide Vanadate CN − H2PO4− HCO2− HCO3− HSO4− HS− OH− ClO− IO3− NO3− NO2− ClO4− MnO4− SCN− I3− VO3− * * * * * 3Carbide Carbonate Chromate Dichromate Imide Manganate Metasilicate Monohydrogen phosphate Oxalate Peroxide Peroxydisulfate Phthalate Polysulfide Selenate Sulfate Sulfite Tartrate Tellurate Tetraborate Thiosulfate Tungstate Zincate C2−2 CO3−2 CrO4−2 Cr2O7−2 −2 NH MnO4−2 SiO3−2 HPO4−2 * C2O4−2 O2−2 S2O8−2 C8H4O4−2 Sx−2 SeO4−2 SO4−2 SO3−2 C4H4O6−2 TeO4−2 B4O7−2 S2O3−2 WO4−2 ZnO2−2 4- Aluminate Arsenate Borate Citrate Phosphate Phosphite Orhtosilicate AlO3−3 AsO4−3 BO3−3 C6H5O7−3 PO4−3 PO3−3 Pyrophosphate SiO4−4 P2O7−4 Tri-polyphosphate P3O10−5 5- CATIONS: 1+ * Ammonium Hydronium NH4+ H3 O+ The subscript is used to indicate the number of atoms for each element present. Ex. N3− The symbol indicates the type of element present in the compound. Ex. Na= Sodium The coefficient is used to indicate the total number of molecules present. Ex. 3C8H10N4O2The superscript is used to indicate the oxidation number of each element or polyatomic ion. Ex. AlO3−3 The formula is a combination of symbols that represent the composition of a compound Ex. C4H4O6−2 Transition elements Oxidation states for transition elements *Silver Ag+ Iron (II) Fe+2 NON-METALS Oxidation states N-3 Nitride Cu+ P-3 Phosphide Copper (II) Cu+2 O-2 Oxide Cobalt (II) Co+2 Cobalt (III) Co+3 S-2 Sulfide Tin (II) Sn+2 F-1 Fluoride Tin (IV) Sn+4 Lead (II) Pb+2 Cl-1 Chloride Lead (IV) Pb+4 Br-1 Bromide Mercury (I) Hg2 + I-1 Iodide Mercury (II) Hg+2 *Zinc Zn+2 Iron (III) Fe+3 *Cadmium Cd+2 Copper (I) 12 Prefix System Prefixes for binary molecular compounds. 1 2 3 4 5 Mono Di Tri Tetra Penta 6 7 8 9 10 Hexa Hepta Octo Nona Deca TERNARY ACIDS Know all forms of ClO3-1 and IO3-1 Per--------ic --------ic --------ous Hypo--------ous Greatest # of O atoms Greater # of O atoms Smaller # of O atoms Smallest # of O atoms