AP Ch2: Atoms, Molecules and ions History of Chemistry • 400 B.C: Democritus (greek philosopher) hypothesizes that all matter is composed of tiny particles called atoms. Atoms vs Hyle • 1500’s: Georg BauerGermany, develops systematic metallurgy. How to extract metals from raw ore. Robert Boyle-1st true chemist • Wrote: The Skeptical Chymist • Developed P1V1 = P2V2 Boyle’s Law Joseph Priestly • 1700’s: English clergyman discovers oxygen! Priestly ROCKS! Antoine Lavoisier • 1700’s: French chemist, uses combustion reaction to verify the law of conservation of mass, mass cannot be created nor destroyed by ordinary chemical reactions. Joseph Proust • Proust’s Law: “The Law of Definite Proportions: A given compound always contains exactly the same proportions of elements by mass” Example: CuCO3 is always 51% Cu, 10% C and 39% O, by mass. John Dalton….THE MAN! John Dalton 1 • Formulates the law of multiple proportions: Elements can combine to form a series of compounds. Example: N2O dinitrogen monoxide N + O2 NO nitrogen monoxide NO2 nitrogen dioxide NO1/2 cannot form John Dalton 2 • Formulates Atomic Theory: 1) Each element is made up of tiny particles called atoms. The atoms of a given element are identical. Chemical compounds are formed when atoms come together, in simple whole number ratios. Chemical reactions involve the reorganization of the atoms; combined, separated or rearranged. 2) 3) 4) 1808: Gay-Lussac • Develops: P1/T1 = P2/T2 1903: J.J. THOMSON • Discovers the electron, using his famous Cathode Ray Tube (CRT), which turns out to be a primitive TV or computer monitor. He also calculated the charge of electron to be -1.76 x 108 Coulombs per gram. 1909 Millikan finds the charge of an electron. • Robert Millikan finds the charge on the electron to be -1.6 x 10-19 Coulombs Robert Millikan’s Oil Drop Experiment CRT and TV 1900’s Eugene Goldstein discovers that beams of particles travel in the opposite direction as cathode rays. These particles are protons. 1911 Ernest Rutherford • Rutherford discovers the nucleus of an atom, using his famous gold foil experiment. His native New Zealand put his image on money. Rutherford’s Gold Foil Experiment Rutherford’s Gold Foil Experiment James Chadwick • Chadwick, Rutherford’s assistant, later made the observation that when gold nuclei are radiated with alpha particles, they sometimes emit particles, which are not affected by a charge. This was the discovery of the neutron. Nuclear Radiation Type Alpha symbol a make-up 2p+ & 2no mass 4 amu Beta B high speed electron 1/1840 amu Gamma g high energy photon 0 amu Positron e+ beta antiparticle 1/1840 amu penetrating power low medium high high Penetrating Power Periodic Table: The Basics Classes of elements to know: • • • • • • • • • Group 1: Alkali metals Group 2: Alkaline-earth metals Groups 3-12: Transition Metals B, Si, As, Te, Ge, Sb are metalloids Group 17: Halogens Group 18: Noble Gases Elements #57-70: Rare-Earth Metals Elements #89-102: Radioactive Series *All elements with an atomic number greater than 83 and Tc have all radioactive isotopes. • **All elements on the periodic table on the wall which are outlined are synthetic. Nomenclature: Naming Chemical Compounds • 1) 2) 3) 4) 5) The types of chemical compounds you need to know for this chapter: Covalent binary Ionic binary A) singlevalent cation (s-block) B) multivalent cation (transition metal) Ionic ternary (containing a polyatomic ion) Ionic ternary hydrates Acids Binary Covalent: prefix___ prefix___ + ide (2 nonmetals) # of atoms 1 2 3 4 5 6 7 prefix monoditritetrapenthexhept- examples CO2 CCl4 NO2 N2O5 P2O3 SO3 SO2 Binary ionic: cation anion+ide (metal + nonmetal) Formula KCl Name magnesium chloride NaBr lithium oxide Al2O3 calcium sulfide BeF2 strontium nitride NaH Ionic w/ a multi-valent(transition metal) cation • The oxidation number of the cation is always given in roman numerals, in parethesis. Common cations to memorize: • Cr 2+ = chromium (II) aka: chromous Cr 3+ = chromium (III) aka: chromic • Fe 2+ = iron (II) aka: ferrous Fe 3+ = iron (III) aka: ferric • Co 2+ = cobalt (II) Co 3+ = cobalt (III) • Ni 2+ = nickel (II) Ni 3+ = nickel (III) • Cu + = copper (I) aka: cuprous Cu 2+ = copper (II) aka: cupric • Sn 2+ = tin (II) aka stannous Sn 4+ = tin (IV) aka stannic • Pb 2+ = lead (II) aka plumbous Pb 4+ = lead (II) aka plumbic Indicates the most common form Hydrates: • Name ionic compound + _______ hydrate (prefix) Example: CuSO4 . 5 H2O copper (II) sulfate pentahydrate Acids Binary acids = hydro-_____-ic acid Ternary acids(oxyacids): Name anion, ite = ous acid OR Name anion, ate = ic acid POP QUIZ!!!!! • Name the following compounds: Na2S Fe(NO3)3 Mg(C2H3O2)2 NH4NO2 K2CO3 S2O5 CuCl Zn(ClO3)2 CuCl2 Zn(ClO4)2 CuCl2.3H2O Zn(ClO2)2 H2CO3 Zn(ClO)2 N2O3 HCl HClO2 HClO4 HClO3 END OF CHAPTER 2