Chemistry Notes Part 1

Elements Something that can not be broken down into a simpler form and maintain characteristic properties Made up of only ONE type of atom

Dimitri Mendeleev Russian Scientist Invented the periodic table of elements Only 50 known elements 1860s Predicted new elements Dimitri Mendeleev

Now: 118 known elements #1-92 occur naturally Only 88 are naturally found on earth

Matter “Stuff” or “LEGOS®” of the universe Solid Liquid Gas Plasma BEC (Bose-Einstein Condensate)

Atom Sub atomic particles Basic unit of an element Parts of an atom Electrons: (-) Orbits nucleus Protons: (+) In nucleus Neutrons: (none) Atom Sub atomic particles

Molecule ≥ 2 atoms bonded together Ex: H2O Ex: O2 Ex: CO2

Element (Atomic) Number Electron number of an atom Atomic Mass Atomic # = # of Protons Typically # of electrons = # of protons Mass of protons and neutrons

Neutron # Atomic mass minus atomic number= # of neutrons EX: O (Oxygen) Protons (+) = 8 Electrons (-) = 8 Neutrons (0) = 8 (16-8)=8 Atomic # Symbol Name Atomic Mass

Rows Columns Periods Groups of Families How many electron orbitals (shells) an atom has Groups of Families Have similar characteristics and properties Same # of valence electrons

Valence Electrons Outer electrons of an atom Important for + are responsible for chemical reactions