Atomic theory of matter, 1807 – John Dalton (paraphrased postulates) Elements are composed of atoms, which are very small Atoms of a given element are identical and different from atoms of another element* Atoms cannot be changed, destroyed, or created in a chemical reaction* Compounds are formed from atoms and the relative quantity and identity of atoms are always the same for a given pure compound

J.J. Thompson – cathode ray tubes – charge-to-mass ratio of electrons Robert Millikan – oil-drop experiment – charge on electrons (therefore mass) Marie Curie – radioactivity – identified sub-atomic particles Ernest Rutherford – gold leaf experiment – revealed the nuclear atom

Cathode Rays and Electrons

Cathode Rays and Electrons

Radioactivity

AN EXAMPLE: fill in the following chart Symbol 52Cr Protons 43 55 Neutrons 49 114 Electrons 89 57 Mass # 139 133

Chemical Nomenclature Common names (water, ammonia, etc.) Ionic compounds Cations Group 1 and 2 metals (first 2 columns): same name as element Transition metals Add Roman numeral to denote charge: e.g. Fe3+  Iron (III) Or, use Latin names: e.g. Fe3+  ferric ion, Fe2+  ferrous ion Molecular cations tend to end in “ium”: e.g. NH4+  ammonium, H3O+  hydronium

Chemical Nomenclature Common names Ionic compounds Cations Anions Monatomic anions: replace suffix with “ide” Cl-  chloride N3-  nitride Polyatomic anions containing oxygen (oxyanions) Most “common”  ends in “ate” One less oxygen than “ate” version  ends in “ite”

Chemical Nomenclature Common names Ionic compounds Cations Anions Monatomic anions: replace suffix with “ide” Polyatomic anions containing oxygen (oxyanions) Most “common”  ends in “ate” One fewer oxygen than “ate” version  ends in “ite” One more oxygen than “ate” version  starts with “per” / ends in “ate” One fewer oxygen than “ite” version  starts with “hypo” / end in “ite” ClO-  hypochlorite ClO2-  chlorite ClO3-  chlorate ClO4-  perchlorate

Chemical Nomenclature Common names Ionic compounds Cations Anions Monatomic anions: replace suffix with “ide” Polyatomic anions containing oxygen (oxyanions) Oxyanions containing hydrogen One hydrogen: add “hydrogen” to start of name (add +1 to charge) Two hydrogens: add “dihydrogen” to start of name (add +2 to charge) PO43-  phosphate HPO42-  hydrogen phosphate H2PO4-  dihydrogen phosphate

Chemical Nomenclature Common names Ionic compounds Cations Anions Compounds (omit subscripts in name) LiF  ? aluminum sulfite  ? FeHPO4  ?

Chemical Nomenclature Common names Ionic compounds Cations Anions Compounds Hydrates (some ionic compounds include “waters of hydration”) FeCl3  iron (III) chloride FeCl3 • 6H2O  iron (III) chloride hexahydrate

Chemical Nomenclature Common names Ionic compounds Acids (anions with hydrogen cations) From anions ending in “ide”  prefix “hydro”, change “ide” to “ic acid” From oxyanions For oxyanions ending in “ate”  change “ate” to “ic acid” For oxyanions ending in “ite”  change “ite” to “ous acid” HI  hydroiodic acid HNO3  nitric acid (H2SO4  sulfuric acid) HClO  hypochlorous acid

Chemical Nomenclature Common names Ionic compounds Acids Binary molecular compounds The leftmost (or bottom-most) element on the periodic table goes first … unless it’s oxygen, which always goes last … unless oxygen is paired with fluorine, and then it’s first again The name of the second element is given the “ide” suffix Use Greek prefixes (mono, di, tri, tetra, etc.) to indicate number of atoms … but don’t uses “mono” for first element PCl5  phosphorous pentachloride N2O3  dinitrogen trioxide

Chemical Nomenclature Common names Ionic compounds Acids Binary molecular compounds Basic organic compounds Alkanes Alcohols Organic acids