Mendeleev

• First organize elements by properties (mass, density, color, etc)
• Observed that # of VE went in a pattern of 1,2,3,4,3,2,1.
• Arranged elements into rows of 7, they all fell into columns and had same valence #.
• Arranged elements by increasing atomic mass
• Missing blocks for future elements
• Mosley improved periodic table by grouping elements by atomic #.

Periodic Law

• Periodic recurrence of chemical and physical properties of the elements when they're arranged in order of increasing atomic number.
• Examples: Ionization energy, melting point, boiling point, mass, density, atomic radius. etc.

The recurring sequence of pattern of a property w/ increasing atomic number from L->R and T->B in a periodic table.

Anatomy of Periodic Table

• 7 Periods - the number of the period indicates the # of E shells present
• 18 Columns - number of valence electrons present (excluding transition metals)

Metals

• Shiny, hard
• Solids
• good conductors of heat/electricity
• malleable & ductile
• High MP & BP

Metalloids

• Semi-good conductors of heat/electricity
• Properties are btwn metals and non metals.
• Metalloids used in PC's & integrated circuits

• Dull
• Exist in three states of matter
• Poor conductors
• Low MP, BP

• the effect wherby the inner E/shells protect the outer E/shells from the actual nuclear charge

• The charge/force experienced by the outer E/shells after having considered the shielding effect of the inner E/shells.

• Minimum amt. of energy required to remove an electron from the outermost electron shell from any given atom.
• Ionization energy increases across a period and decreases down a family.

• Distance from the nucleus in an atom to the outermost electron shell.
• Atomic radius decreases across a period and increases down a family.

• Amt. of energy required to remove an electron from it's outermost electron shell.
• Increases across a period and decreases down a family.