* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chemistry 1 Lectures
Metastable inner-shell molecular state wikipedia , lookup
Debye–Hückel equation wikipedia , lookup
Physical organic chemistry wikipedia , lookup
Nucleophilic acyl substitution wikipedia , lookup
Isotopic labeling wikipedia , lookup
Artificial photosynthesis wikipedia , lookup
Resonance (chemistry) wikipedia , lookup
Biological aspects of fluorine wikipedia , lookup
Electrolysis of water wikipedia , lookup
Metallic bonding wikipedia , lookup
List of phenyltropanes wikipedia , lookup
History of chemistry wikipedia , lookup
Rutherford backscattering spectrometry wikipedia , lookup
Chemistry: A Volatile History wikipedia , lookup
Biochemistry wikipedia , lookup
Aromaticity wikipedia , lookup
Acid–base reaction wikipedia , lookup
Nanofluidic circuitry wikipedia , lookup
Gas chromatography–mass spectrometry wikipedia , lookup
Coordination complex wikipedia , lookup
Drug discovery wikipedia , lookup
Hypervalent molecule wikipedia , lookup
Atomic theory wikipedia , lookup
Chemical bond wikipedia , lookup
History of molecular theory wikipedia , lookup
Organic chemistry wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Metalloprotein wikipedia , lookup
Ionic compound wikipedia , lookup
Homoaromaticity wikipedia , lookup
Inorganic chemistry wikipedia , lookup
IUPAC nomenclature of inorganic chemistry 2005 wikipedia , lookup
Molecules and Compounds ed. Brad Collins Some images Copyright © The McGraw-Hill Companies, Inc. Sunday, August 18, 13 A molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical bonds Chemical Bond H2 H 2O NH3 CH4 A diatomic molecule contains only two atoms H2, N2, O2, Br2, HCl, CO A polyatomic molecule contains more than two atoms O3, H2O, NH3, CH4 3.1 Sunday, August 18, 13 Molecules vs. Compounds Molecules are composed of 2 or more atoms Compounds are composed of 2 or more elements Molecules have a definite arrangement of atoms Compounds have a definite ratio of elements, but may or may not have a definite arrangement of those elements Molecules are held together by chemical bonds Compounds may be held together by chemical bonds or by other attractive forces. Examples of molecules: H2, O3 (ozone), NH3, H2O, C6H12O6 Examples of compounds: H2O, CH4, Al2O3, NaCl 3.1 Sunday, August 18, 13 3.1 Sunday, August 18, 13 Molecular mass (or molecular weight) is the sum of the average atomic masses (in amu) in a molecule. 1S SO2 2O SO2 32.07 amu + 2 x 16.00 amu 64.07 amu For any molecule molecular mass (amu) = molar mass (grams) 1 molecule SO2 = 64.07 amu 1 mole SO2 = 64.07 g SO2 3.1 Sunday, August 18, 13 Do You Understand Molecular Mass? How many H atoms are in 72.5 g of C3H8O ? 1 mol C3H8O = (3 x 12) + (8 x 1) + 16 = 60 g C3H8O 1 mol C3H8O molecules = 8 mol H atoms 1 mol H = 6.022 x 1023 atoms H 1 mol C3H8O 8 mol H atoms 6.022 x 1023 H atoms 72.5 g C3H8O x x x = 1 mol H atoms 60 g C3H8O 1 mol C3H8O 5.82 x 1024 atoms H 3.1 Sunday, August 18, 13 Organic vs. Inorganic Compounds • Organic compounds are carbon-containing substances • Do not include carbon-oxides, e.g., carbon dioxide (CO2), carbon monoxide (CO) or carbonate (CO32–) • 20-30 million known organic compounds • Carbon can concatenate (C–C– C–C– C–C– C–C–C) • Inorganic compounds are substances based on all the other elements. • ~500,000 known inorganic compounds 3.1 Sunday, August 18, 13 Ionic Compounds • Compounds composed of ions • Ionic compounds don’t exist as molecules. • Exist as 3-dimensional networks of ions: crystal lattice A monatomic ion contains only one atom Na+, Cl–, Ca2+, O2–, Al3+, N3– A polyatomic ion contains more than one atom OH–, CN–, NH4+, NO3– Sunday, August 18, 13 3.2 Examples of Monatomic Ions 3.2 Sunday, August 18, 13 Do You Understand Ions? How many protons and electrons are in 27 3+ 13 Al ? 13 protons, 10 (13 – 3) electrons For cations subtract the charge from the number of protons How many protons and electrons are in 78 234 Se ? 34 protons, 36 (34 + 2) electrons For anions add the charge to the number of protons 3.2 Sunday, August 18, 13 ionic compounds consist of a combination of cations and anions • the formula is always the same as the empirical formula • the sum of the charges on the cation(s) and anion(s) in each formula unit must equal zero The ionic compound NaCl 3.2 Sunday, August 18, 13 Formulas of Ionic Compounds 2 x +3 = +6 3 x -2 = -6 Al2O3 Al3+ 1 x +2 = +2 Ca2+ 1 x +2 = +2 Na+ O22 x -1 = -2 CaBr2 Br– 1 x -2 = -2 Na2CO3 CO323.2 Sunday, August 18, 13 A molecular formula shows the exact number of atoms of each element in the smallest unit of a molecule. An empirical formula shows the simplest whole-number ratio of the atoms in a substance molecular empirical H 2O H2O C6H12O6 CH2O O3 O N2H4 NH2 Formulas for ionic compounds always reflect their empirical formulas. Sunday, August 18, 13 3.2 Hydrated Compounds Definition: Ionic compounds (usually) that have a specific number of water molecules trapped in their crystal lattice. CuSO4 • 5 H2O copper sulfate pentahydrate Anhydrous (anhydride) - a hydrate with the water molecules driven off (usually upon heating) CuSO4 copper sulfate Molecular mass of hydrates: Include the mass of water given in the formula. 3.2 Sunday, August 18, 13 Covalent Compounds An atomic force microscopy image of a graphene molecule A ball-and-stick model of graphene Image credit: IBM Research 3.3 Sunday, August 18, 13 Covalent Compounds • Electrons are shared between 2 atoms in a covalent bond. • Do not give up or take electrons - no ions formed • Usually between 2 non-metals, or a non-metal and metaloid • Formulas for covalent compounds are molecular formulas. • Examples: Sunday, August 18, 13 • NH3 ammonia • H2O water (dihydrogen oxide) • CO2 carbon dioxide 3.3 Naming Compounds Organic Compounds: Contain carbon (except oxides, sulfides, cyanide) Inorganic Compounds: Everything else, divided into 4 classes Ionic compounds Molecular compounds Acids and Bases Hydrates 3.4 Sunday, August 18, 13 Chemical Nomenclature • Ionic Compounds – often a metal + nonmetal (binary compounds) – anion (nonmetal), add “ide” to element name BaCl2 barium chloride K2O potassium oxide MgCl2 magnesium chloride K3N potassium nitride 3.4 Sunday, August 18, 13 3.4 Sunday, August 18, 13 Naming Polyatomic Ions: 8 “-ates” + 5 Names for all the polyatomic ions and the acids derived from them can be derived from the names of 12 core ions: 8 “-ates” + 4 8 “-ates” “+ 5” carbonate CO32– cyanide CN– chlorate ClO3– thiocyanate SCN– chromate CrO42– hydroxide OH– dichromate Cr2O72– peroxide O2– nitrate NO3– ammonium phosphate PO43– NH4+ manganate MnO3– sulfate SO42– Sunday, August 18, 13 per- ____ -ate hypo- ____ -ite Hydrogen in front of an “-ate” ion is named hydrogen ____ -ate, except sulfate, which is bisulfate. Naming Ionic Compounds • With Polyatomic Ions – sometimes a metal + polyatomic ion – Use the metal and the polyatomic ion naming rules Ba(ClO2)2 barium chlorite KNO3 potassium nitrate Mg(OH)2 magnesium hydroxide KClO4 potassium perchlorate 3.4 Sunday, August 18, 13 Naming Ionic Compounds • Transition metal ionic compounds have variable charges – Iron can be +2 or +3 – Smaller charge is sometimes named as an ‘ic’ ion higher charge as an ‘ous’ ion – So in ferric chloride (FeCl2) iron ion is Fe2+ – Modern method is to indicate charge on the metal with Roman numerals – So FeCl2 is now named iron(II) chloride FeCl2 2 Cl- are -2 so Fe is +2 iron(II) chloride FeCl3 3 Cl- are -3 so Fe is +3 iron(III) chloride Cr2S3 3 S-2 are -6 so Cr is +3 (6/2) chromium(III) sulfide 3.4 Sunday, August 18, 13 • Covalent compounds • Between 2 (or more) nonmetals or nonmetals + metalloids • Naming: • Some have common names: • H2O, NH3, CH4, C60 • Otherwise: • Element further left in periodic table is 1st • Element closest to bottom of group is 1st • Last element ends in ide (for inorganics) • If more than one compound can be formed from the same elements, use prefixes to indicate number of each kind of atom 3.4 Sunday, August 18, 13 Covalent Compounds HI hydrogen iodide NF3 nitrogen trifluoride SO2 sulfur dioxide N2Cl4 dinitrogen tetrachloride NO2 nitrogen dioxide N2O dinitrogen monoxide TOXIC! Laughing Gas 3.4 Sunday, August 18, 13 Exceptions: Molecular Compounds B2H6 diborane CH4 methane SiH4 silane NH3 ammonia PH3 phosphine H2O water H2S hydrogen sulfide 3.4 Sunday, August 18, 13 Naming Compounds Compound Ionic Molecular NH4+ Metal or plus mono or polyatomic anion Yes Alkali metal ions Alkaline earth metal ions Ag+, Al3+, Cd2+, Zn2+ ✤ Name metal ion first, then anion ✤ If monatomic anion, add “ide” to the end of the root of the element name ✤ If polyatomic ion, use 8 “-ates” + 4 rules Sunday, August 18, 13 Cation has only one charge Binary compounds of nonmetals or nonmetals and metalloids No Transition metal cations ✤ Name metal ion first ✤ Specify charge on cation with a Roman numberal ✤ If monatomic anion, add “ide” to the end of the root of the element name ✤ If polyatomic ion, use 8 “-ates” + 4 rules ✤ Name element furthest left or furthest down in a group first. ✤ Add “ide” to the end of the root of the second element’s name ✤ Use prefixes to designate the numbers of each element present ✤ The mono prefix is usually omitted 3.4 Practice • Name the following compounds: • SiCl4 • P4O10 • What are the formulas for the following compounds? • carbon dioxide • disilicon hexabromide 3.4 Sunday, August 18, 13 Acids and Bases An acid can be defined as a substance that yields hydrogen ions (H+) when dissolved in water. HCl •Pure substance, hydrogen chloride •Dissolved in water (H+ Cl-), hydrochloric acid Binary acids consist of hydrogen and one other atom: •Examples: HF, HCl, HBr, HI, H2S 3.4 Sunday, August 18, 13 Naming Binary Acids “-ides” are “-ic”-y 3.4 Sunday, August 18, 13 An oxoacid is an acid that contains hydrogen, oxygen, and another element. HNO3 nitric acid H2CO3 carbonic acid H2SO4 sulfuric acid HNO3 “-ates” are “-ic”-y and “-ites” “-ous” Sunday, August 18, 13 3.4 Naming Oxo-acids Per______ate ______ate ______ite hypo______ite Add H+ Add H+ Per______ic acid ______ic acid “Representative” -ic acid Add H+ Add H+ ______ous acid hypo______ous 3.4 Sunday, August 18, 13 Worked Examples 2.8 3.4 Sunday, August 18, 13 Acids and Bases A base can be defined as a substance that yields hydroxide ions (OH–) when dissolved in water. NaOH KOH Ba(OH)2 sodium hydroxide potassium hydroxide barium hydroxide Name the cation, then add “hydroxide” Don’t use prefixes with “hydroxide” 3.4 Sunday, August 18, 13 3.4 Sunday, August 18, 13