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Chemistry Notes Part 1 • Greek Philosopher • 4 Elements Earth Fire Water Air Emphedocles --• Elements • Something that can not be broken down into a simpler form and maintain characteristic properties Made up of only ONE type of atom --Russian Scientist Invented the periodic table of elements Only 50 known elements 1860s Predicted new elements • Now: 118 known elements #1-92 occur naturally Only 88 are naturally found on earth --• “Stuff” or “LEGOS®” of the universe Solid Liquid Gas Plasma BEC (Bose-Einstein Condensate) --• Greek Philosopher • Atom is “indivisible” --• Basic unit of an element --• Parts of an atom Electrons: (-) Orbits nucleus ≈.0000001 amu (atomic mass unit) • • Dimitri Mendeleev Matter Democritus Atom Sub atomic particles --Molecule Element (Atomic) Number Electron number of an atom In nucleus ≈1 amu • • • • ≥ 2 atoms bonded together Ex: H2O Ex: O2 Ex: CO2 • Atomic # = # of Protons ------- • Atom is electrically neutral # of electrons = # of protons • Atomic mass Mass of protons and neutrons --Atomic mass – atomic number= # of neutrons EX: O (Oxygen) +=8 -=8 0 = 8 (16-8) Ex: Fe (Iron) Ex: Mg (Magnesium) • Neutron # --Rows Columns Valence electrons Protons: (+) In nucleus ≈1 amu Neutrons: (none) • Periods How many electron orbitals (shells) an atom has --• Groups of Families • Have similar characteristics and properties • Same # of valence electrons --• Outer electrons of an atom • Important for + are responsible for chemical reactions