1. CHEMISTRY 161 Chapter 2

2. proton, p 1.67262 × 10 -27 kg +1.6022 × 10 -19 C +1 electron, e 9.10939 × 10 -31 kg -1.6022 × 10 -19 C -1 neutron, n 1.67493 × 10 -27 kg 0 0 Subatomic Particles (1897 – 1932)

3. 2.3. Periodic System of the Elements Mendeleev (1869) Atomic Weight ElementProperty 6.9Lithiumactive metal 9.0Berylliummetal 10.8Boronnonmetallic solid 12.0Carbonnonmetallic solid 14.0Nitrogennonmetal, inactive gas 16.0Oxygennonmetal, active gas 19.0Fluorinenonmetal, very active gas 23.0Sodiumvery active metal, properties like Li 24.3Magnesiumactive metal 27.0Aluminummetal 28.1Siliconnonmetallic solid 31.0Phosphorousnonmetallic solid, properties like N 32.1Sulfurnonmetallic solid, properties like O 35.5Chlorinenonmetallic gas, properties like F 39.1Potassiumvery active metal, properties like Na 40.1Calciumactive metal, properties like Mg

4. Now rearrange by properties: 6.9 Li active metal 9.0 Be metal 10.8 B nonmetallic solid 12.0 C nonmetallic solid 14.0 N nonmetal, inactive gas 16.0 O nonmetal, active gas 19.0 F nonmetal, very active gas 23.0 Na very active metal, chemical properties like Li 24.3 Mg active metal 27.0 Al metal 28.1 Si nonmetallic solid 31.0 P nonmetallic solid, chemical properties like N 32.1 S nonmetallic solid, chemical properties like O 35.5 Cl nonmetallic gas, chemical properties like F 39.1 K very active metal, chemical properties like Na 40.1 Ca active metal, chemical properties like Mg Mendeleev’s Periodic System “The properties of the elements ….are in periodic dependence ….. on the atomic weights of the elements."

5. 2.4. Atomic Number, Mass Number, Isotopes atomic number (number of protons) (number of electrons) mass number (number of protons plus neutrons)

6. Mendeleev 1869 “The properties of the elements ….are in periodic dependence ….. on the atomic weights of the elements." Theory of the Atom 1897-1932 “The properties of the elements ….are in periodic dependence ….. on the atomic weights of the atomic number." Periodic System of the Elements

7. 1.Periodic System of the Elements 1.1. periods, groups 1.2. metals, nonmetals, semimetals atomic number, mass number 2. Combination of Atoms 2.1. diatomics, polyatomics 2.2. neutrals, ions (cations, anions) 3. Quantification chemical formula, empirical formula

8. Homework Chapter 2, p. 43-53 problems, group 1 – 8 elements