CHEMISTRY NOTES: CHEMICAL NAMES AND FORMULAS

Transcription

1 CHEMISTRY NOTES: CHEMICAL NAMES AND FORMULAS I. PERIODIC TABLE schematic presentation of the elements according to their periodic properties, arranged by increasing atomic number A. general layout 1) GROUP vertical column a) REPRESENTATIVE ELEMENTS group A elements b) TRANSITION ELEMENTS group B elements c) INNER TRANTITION ELEMENTS (rare earth metals) 2 footnotes 2) PERIOD horizontal row (17) B. metals, nonmetals, and metalloids 1) metals a) most of the periodic table is composed of metals b) metal characteristics: luster, ductility, malleability, conductivity 2) nonmetals a) found in the upper righthand corner of the chart b) nonmetal characteristics: nonlustrous, poor conductors 3) metalloids (semimetals, semiconductors) elements having properties of metals and nonmetals (they border the staircase) THE METALLOIDS: B, Si, Ge, As, Sb, Te, Po (Al is classified as other metal and At is a nonmetal) C. a staircase divides the metals from the nonmetals D. common elements to know Ag, Al, Ar, As, Au, B, Ba, Be, Bi, Br, C, Ca, Cl, Co, Cr, Cs, Cu, F, Fe, Fr, H, He, Hg, I, K, Kr, Li, Mg, Mn, N, Na, Ne, Ni, O, P, Pb, Ra, Rb, S, Sb, Si, Sr, Sn, U, W, Zn E. early classifications 1) Johann Dobereiner ( ) 1817: found groups of three elements ( triads ) that have related properties 2) John Newlands ( ) 1863: Law of Octaves repetition of properties observed every eighth element 3) Dmitri Mendeleev ( ) 1869: arranged elements according to atomic masses left blank spots where the elements did not seem to fit in II. Atoms and Ions A. atomic charge: neutral (net charge of zero) # protons = # electrons B. ION charged atom(s) or group of atoms 1) formed by gain or loss of electrons 2) CATION a positive ion formed by losing electrons 3) ANION a negative ion formed by gaining electrons common ending is IDE (chloride, bromide, iodide...) CP AN Cations Positive, Anions Negative Cat People Are Nice YOU CAN T LOSE OR GAIN PROTONS TO FORM AN ION! 4) an ion has different properties than its element (Na atom vs. Na ion) 5) examples... Q: Aluminum loses three electrons when its ion is formed. Write its symbol and charge. A: Al 3 Q: Oxygen gains two electrons when its ion is formed. Write its symbol and charge. A: O 2

2 III. Compounds A. COMPOUND (cmpd.) a substance formed from more than one element B. Law of Definite Proportions 1) compounds form from elements combining in the same mass ratio 2) atoms combining is simple wholenumber ratios C. MOLECULE a group of atoms with no net charge D. two general types of cmpds. 1) MOLECULAR COMPOUND composed of molecules usually liquids or gases at room temp. usually have a low melting point (m.p.) and boiling point (b.p.) composed of nonmetals like CO 2 2) IONIC COMPOUNDS composed of positive/negative ions usually crystalline solids at room temp. usually have a high melting point (m.p.) and boiling point (b.p.) composed of metals and nonmetal like NaCl THE SEVEN DIATOMIC MOLECULES: H 2 F 2 O 2 N 2 Cl 2 Br 2 I 2 IV. Chemical formulas A. CHEMICAL FORMULA 1) symbols representing the composition of the smallest unit of a substance 2) shows which elements are present and how many there are H 2 SO 4 hydrogen, sulfur, oxygen 7 atoms total B. MOLECULAR FORMULA symbols representing the composition of a molecule C. FORMULA UNIT the lowest wholenumber ratio if ions in an ionic compound It is improper to use the term molecule to describe an ionic compound. Ionic compounds occur in repeating units in their crystals. D. number codes 1) SUBSCRIPT a number written slightly below the symbol Br 2 2) SUPERSCRIPT a number written slightly above the symbol Sr 2 (In chem., a superscript is not called an exponent. Nothing is being multiplied.) V. Laws of Definite and Multiple Proportions A. Law of Definite Proportions in any compound, the masses of the elements are always in the same proportions B. Law of Multiple Proportions the ratio of elements that form more than one (multiple) compounds will always be a wholenumber ratio C. example PROPORTIONS OF TIN AND OXYGEN IN tin(ii) oxide and tin(iv) oxide: TOTAL MASS Sn TOTAL MASS O RATIO Sn:O SnO 119 amu 16 amu 1:1 SnO2 119 amu 32 amu 1:2 VI. Ionic Charges of the Elements A. pattern ( Charge Chant : no O!) Group IA IIA IIIA IVA VA* VIA* VIIA* 0 (VIIIA) x none x most of Group IVA don t usually form ions

3 * when applicable B. metals form cations () nonmetals form anions () C. multiple charges (transition metals) 1) Stock system uses number clues 2) Classical (Latin root) system LOWER CHARGED ION: suffix OUS Cu = cuprous ion HIGHER CHARGED ION: suffix IC Cu 2 = cupric ion ION FORMULA STOCK NAME CLASSICAL NAME Cu copper(i) ion cuprous ion Cu 2 copper(ii) ion cupric ion Fe 2 iron(ii) ion ferrous ion Fe 3 iron(iii) ion ferric ion Hg 2 mercury(i) ion mercurous ion 2 Hg 2 mercury(ii) ion mercuric ion Pb 2 lead(ii) ion plumbous ion Pb 4 lead(iv) ion plumbic ion Sn 2 tin(ii) ion stannous ion Sn 4 tin(iv) ion stannic ion Cr 2 chromium(ii) ion chromous ion Cr 3 chromium(iii) ion chromic ion Mn 2 manganese(ii) ion manganous ion Mn 3 manganese(iii) ion manganic ion Co 2 cobalt(ii) ion cobaltous ion Co 3 cobalt(iii) ion cobaltic ion 3) onecharge transition metal ions: Ag, Cd 2, Zn 2 VII. Polyatomic ions A. a group of charged atoms B. most end in ATE or ITE IMPORTANT POLYATOMIC IONS TO MEMORIZE: 1 CHARGE: ammonium NH 4 1 CHARGE: acetate C 2 H 3 O 2 or CH 3 COO chlorate ClO 3 chlorite ClO 2 cyanide CN dihydrogen phosphate H 2 PO 4 hydrogen carbonate or bicarbonate HCO 3 hydrogen sulfate or bisulfate HSO 4 hydrogen sulfite or bisulfite HSO 3 hydroxide OH hypochlorite ClO nitrate NO 3 nitrite NO 2 perchlorate ClO 4 permanganate MnO 4 2 CHARGE: carbonate CO 3 2 chromate CrO 4 2 dichromate Cr 2 O 7 2 hydrogen phosphate HPO 4 2 oxalate C 2 O 4 2 silicate SiO 3 2 sulfite SO 3 2 sulfate SO CHARGE: phosphite PO 3 3 phosphate PO 4 3

4 VIII. Common vs. Systematic Names A. common names do not discuss chemical composition B. systematic names are a standardized way of naming compounds C. some common names for chemicals: asbestos = magnesium silicate aspirin = acetylsalicylic acid baking soda = sodium bicarbonate black lead = graphite borax = sodium borate brine = strong sodium chloride solution chalk = calcium carbonate drinking alcohol = ethanol Epsom salts = magnesium sulfate laughing gas = dinitrogen monoxide lime = calcium oxide lime, slaked = calcium hydroxide limewater = calcium hydroxide solution table salt = sodium chloride quicksilver = mercury silica = silicon dioxide soda ash, dry = dry sodium carbonate soda lye = sodium hydroxide soluble glass = sodium silicate talc or talcum = magnesium silicate vinegar = dilute acetic acid Vitamin C = ascorbic acid water = H 2 O water glass = sodium silicate IX. BINARY COMPOUNDS: BINARY IONIC & BINARY MOLECULAR A. BINARY CMPD. composed of two elements 1) compound composed of monatomic ions 2) net charge must be zero B. crisscross formula method 1) write the symbols of the two ions next to each other 2) write the charges as superscripts 3) balance the formula by crisscrossing the numbers C. BINARY IONIC CMPDS. metal cation / nonmetal anion combination 1) name the cation first, then the anion (IDE ending) 2) use Roman numerals if/when needed for the cation 3) examples: CaBr 2 calcium bromide; KI potassium iodide; FeCl 3 iron(iii) chloride D. BINARY MOLECULAR CMPDS. nonmetal / nonmetal combination 1) two nonmetallic elements 2) no ionic charges involved 3) ending in IDE 4) prefixes used in naming: MONO, DI, TRI, TETRA, PENTA, HEXA, HEPTA, OCTA, NONA, DECA (mono is not used on the first element) 5) examples: CCl 4 carbon tetrachloride; BF 3 boron trifluoride; CO carbon monoxide X. Ternary Ionic Compounds A. TERNARY CMPD. compound made up of three different elements B. crisscross formula method C. examples: Na 2 SO 4 sodium sulfate; KMnO 4 potassium permanganate; Fe(OH) 3 iron(iii) hydroxide XI. Common Acids ACIDS compounds that donate H ions in solution HX H X acetic acid HC 2 H 3 O 2 or CH 3 COOH hydrochloric acid HCl phosphoric acid H 3 PO 4 carbonic acid H 2 CO 3 nitric acid HNO 3 sulfuric acid H 2 SO 4

5 POLYATOMIC IONS Students must memorize those in boldface type. 1 CHARGE: ammonium NH 4 diammine silver(i) Ag(NH 3 ) 2 hydronium H 3 O pyridinium C 5 H 5 NH 2 CHARGE: mercury(i) Hg CHARGE: acetate C 2 H 3 O 2 or CH 3 COO aluminate AlO 2 amide NH 2 azide N 3 benzoate (C 7 H 5 O 2 ) bromate BrO 3 bromite BrO 2 chlorate ClO 3 chlorite ClO 2 chromite CrO 2 cyanide CN cyanate OCNdihydrogen phosphate H 2 PO 4 formate HCOO hydrogen carbonate or bicarbonate HCO 3 hydrogen sulfate or bisulfate HSO 4 hydrogen sulfite or bisulfite HSO 3 hydroxide OH hypobromite, BrO hypochlorite ClO hypoiodite IO iodate, IO 3 iodite IO 2 nitrate NO 3 nitrite NO 2 perchlorate ClO 4 perbromate, BrO 4 periodate IO 4 (MORE 1 CHARGE:) permanganate MnO 4 superoxide O 2 thiocyanate SCN triflate (trifluoromethanesulfonate) CF 3 SO 3 2 CHARGE: aluminate Al 2 O 4 2 carbide C 2 2 carbonate CO 3 2 chromate CrO 4 2 dichromate Cr 2 O 7 2 disulfate S 2 O 7 2 disulfide S 2 2 hexafluorosilicate SiF 6 2 hydrogen phosphate HPO 4 2 manganate MnO 4 2 molybdate MoO 4 2 oxalate C 2 O 4 2 peroxide O 2 2 selenate SeO 4 2 silicate SiO 3 2 sulfite SO 3 2 sulfate SO 4 2 tartrate C 4 H 4 O 6 2 tetraborate B 4 O 7 2 thiosulfate S 2 O CHARGE: arsenate AsO 4 3 arsenite AsO 3 3 borate BO 3 3 hexacyanoferrate(iii) Fe(CN) 6 3 phosphite PO 3 3 phosphate PO CHARGE: hexacyanoferrate(ii) Fe(CN) 6 4 pyrophosphate P 2 O 7 4