General Chemistry

• Refers to the closeness of the average to the actual or true value

  Accuracy
• How close each measurement to one another

  Precision
• All not zero digits are significant

  Rule 1 Nonzero Digits
• Zeros between nonzero digits are significant

  Rule 2 Captive Zeros
• Zeros from the left are not significant

  Rule 3 Leading Zeros
• Zeros at the end of a number are significant

  Rule 4 Trailing Zeros
• May not significant 


  Rule 5 Final Zeros
• An arrangement of all elements known in accordance with their increasing atomic number and Chemical properties

  Periodic Table of Elements
• Row


  Period
• Column


  Group
• Same valence of electron configuration and chemical properties

  Elements of the same group
• Have an increasing valence electron 


  Element of the same period
• When the energy level of the atom increases…

  The number of energy sub levels increases
• German chemist who formed triads of elements

  Johann Wolfgang Dobereiner 1817
• Triads of elements consist of three components

  Arithmetic mean of atomic masses and two elements present in triad
• An English chemist proposed law of octaves

  John Alexander Reina Newlands 1863
• Elements are arranged in the order of the increasing atomic mass, the properties of every elements are similar to the rest

  Law of Octaves
• Arranges the elements in order of increasing atomic mass

  Dmitri Ivanovic Mendeleev and Julius Lothar Meyer 1869