The Atom What is it? Who discovered it?

Matter: -Has mass and takes up space -Has inertia Made of atoms

History of the Atom -What’s it made of ? *Democritis- mostly empty space with tiny atoms in it *Lavoisier- law of conservation of matter *Dalton- Atomic Theory of matter matter made of unique atoms *Thomson- Discovery of electrons use of cathode rays *Rutherford- nucleus and protons *Chadwick- nucleus and neutrons

Models of the atom: Bohr Model- Electron Cloud Model http://www.colorado.edu/physics/2000/quantumzone/bohr.html Electron Cloud Model http://particleadventure.org/particleadventure/frameless/modern_atom.html

Electron energy levels 1.      seven energy levels 2.      max number of electrons in each level 3.      sublevels (s,p,d, and f)- (refrigerator analogy) electron dot diagram

Elements -made up of the same type of atoms simplest material 109 total so far, 90 naturally occurring

-Periodic table -Mendeleev- Organize information Easy to use chart Listed in Atomic order (sm -> bigger)

*How to use the Chart Atomic number (# of protons) Atomic mass (protons +neutrons) *Isotopes* same element, different number of neutrons

*Classification Groups (families) and Periods Metals Nonmetals Metalloids

Substances Substance- same composition and properties throughout Elements pure substances only one type of atom Compounds more than one type of atom have formulas (NaCl, H20, NaOH, HCl) Law of Definite Proportions

Mixtures- two or more substances together Uniform (homogeneous) Tea, sterling silver, steel Nonuniform (heterogeneous) Pepperoni pizza, milk, OJ, blood

Phases of Matter Solid Liquid Gas

How atoms get together Bonding Sharing Stealing Covalent bonding (CO2,CN-) Hydrogen covalent bonds (H2, H2O) Stealing Ionic bonding (NaCl, HCl)

Chemical Reactions a) All atoms are balanced on each side of the equation b) Can be endothermic or exothermic ie water and photosynthesis