chem flash cards

• atomic mass

  sum of protons and neutrons in nucleus 


  atomic number

  number of protons in nucleus

  OR

  number of electrons in shells

  number of protons are equal to number of electrons -> neutral charge
• isotopes

  atoms of the same element with the same number of protons and electrons but diff numbers of neutrons


  Ar= (mass*%isotope 1) + (mass * % isotope 2) over 100
• compounds and formulas

  compound formed when 2 or more different elements are joined by chemical reactions

  • atoms in a compound are held by chemical bonds

  • properties of compound are diff to elements which made it

  • formula of compound identifies how many atoms of each are present
• rules for writing formulas using ions

  1. name of compound
  2. formula of ions
  3. balance
  4. write formula
  5. use bracket when 2 cap letters in ion AND 1+ of said ion is present
• 7 elements that go as pairs on their own in an equation

  hydrogen

  oxygen

  nitrogen

  fluorine

  chlorine

  bromine

  iodine