Organizing the Elements The Periodic Table Organizing the Elements

Your Periodic Table

The Periodic Table of Elements

Mendeleev’s Periodic Table Elements were arranged horizontally by increasing atomic mass. Elements were grouped vertically according to similar characteristics

Mendeleev’s Breakthrough An element’s properties can be predicted based on its location in the periodic table. Mendeleev was able to predict the existence of 5 yet-to-be- discovered elements Prediction Discovered Ekaaluminium (1871): atomic mass = 68 density = 6.0 Gallium (1875): atomic mass = 69.72 density = 5.904 Ekasilicon (1871): atomic mass = 72 density = 5.5 color = grey Germanium (1886): atomic mass = 72.61 density = 5.35

The Modern Periodic Table Elements are now arranged by increasing atomic number (number of p+). Instead of atomic mass (# of p+ and n0) Elements in vertical columns share similar characteristics. This creates a repeating pattern of characteristics as you move across each row. The word “periodic” means regular, repeated pattern.

4 Important Facts about the Elements Inside the Boxes 4 Important Facts about the Elements 6 12.011 C Carbon Element Name 6 C Carbon 12.011 Element Symbol Atomic Number Atomic Mass (“atomic weight”)

Inside the Boxes 4 Important Facts about the Elements Element Name – Duh… Element Symbol – 1, 2, or 3 letters that represent the name of the element The symbol may or may not be similar to the English name of the element Many derive from the Latin name of the element Atomic Number – The number of protons (p+)found in the nucleus Atomic Mass – The average number of protons (p+) and neutrons (n0) in the nucleus a.m.u. (atomic mass unit) = mass of 1 proton or 1 neutron

Organization GROUPS 18 vertical columns Each group is numbered (# on top of columns) Also called, “families” (i.e. – the lithium family) Elements in a family share similar characteristics Valence Electrons (groups 1-2, 13-18)

Interesting Element “Families” Group 1 (Alkali Metals) are all metals that react violently with water. Group 11 (Copper Family) are all metals that react with water slowly or not at all. Group 18 (Noble Gases) rarely react at all!

Organization PERIODS 7 horizontal rows Each period is numbered (# on left of rows) La’s and Ac’s are part of period 6 and 7 Arranged based on the configuration of electrons (implications in chemical bonding) Periods display a repeating pattern of characteristics

# of p+ increases left to right Patterns in the Table # of p+ increases left to right

atomic mass increases left to right Patterns in the Table atomic mass increases left to right

elements in groups share #’s of valence e- 1 elements in groups share #’s of valence e- 8 2 3 4 5 6 7

similar characteristics

increasing density down the columns

classifications Alkaline Earth Metals Noble Gasses Alkali Metals Halogens Non-Metals Metalloids Transition Metals Lanthanides Actinides

G standard state Gasses L Solids L