Periodic Table
Periodic table - Mendeleyev
• In 1869 Russian chemist Dimitri Mendeleyev classified the elements according to their chemical properties, he noticed patterns were in order with the mass number of the atom.
• Mendeleyev started the development of the periodic table, arranging chemical elements by atomic mass. He predicted the discovery of
other elements, and left spaces open in his periodic table for them.
Periodic table
• Today, we use the periodic table arranged by the atomic number.
• In periodic table atomic number increases while going to the right of the table and also going to down to the table.
• The elements in the periodic table are arranged in order of increasing atomic number.
• In periodic table, the columns are called «group» and the rows are called «period»
Periodic table
• The elements He, Ne, Ar, Kr, Xe, Rn have the atomic number of 2,10,18,36,54, 86.
• These elements follows the octet rule.
• Hence, these elements do not react. They are called noble gases.
Periodic table
• All elements display several trends and we can use the periodic law and table formation to predict their chemical, physical, and atomic properties.
• Understanding these trends is done by analyzing the elements
electron configuration; all elements prefer an octet formation and will gain or lose electrons to form that stable configuration.
Periodic trends
• These periodic trends are:
• Electronegativity
• ionization energy
• electron affinity
• atomic radius
• ionic radius
• metallic character
• chemical reactivity
