Periodic Families

The Periodic Table What does the word periodic mean? pe·ri·od·ic  –adjective 1. recurring at intervals of time: periodic revivals of an interest in handicrafts.  2. occurring or appearing at regular intervals: periodic visits of a mail steamer to an island.  3. repeated at irregular intervals; intermittent: periodic outbreaks of the disease. From Dictionary.com Choose 1 definition and know it!

Mendeleev and the Periodic Table Dmitri Mendeleev  A Russian developed the first periodic table in 1869  He based his table upon the physical properties of the elements  He was even able to predict the properties of undiscovered elements  He made the table 40 years before the discovery of the electron

A gentle reminder Columns on the Periodic Table  They are called Groups or Families Rows on the Periodic Table  Periods Groups and families include similar elements Metals are on the left of the zig-zag line Non-metals on the right of the zig-zag line

How are the elements arranged The elements are arranged by number of protons, the atomic number The elements are not in mass number  Ar, number 18, has a larger mass than K, number 19  The same thing happens with Co and Ni

A new term Valance electrons Electrons in the outermost shell  Remember electron configuration Usually the S and P sub –orbital How many valence electrons in Na, or Cl S can hold 2 and P can hold 6  How many elements in period 2? Coincidence… I think not.

Remember your “People” from outer Space What did you notice as you move down a column? What you did you notice as you across a row? The same thing happens in the periodic table.

Lets take a tour of the Periodic Families

Group 1 Alkali Metals Know this group Metallic, soft Low melting point for a metal Highly reactive One valence electron

Group 2 Alkaline Earth Metals Know this group Higher melting points than alkali metals Soft and lightweight for a metal but harder that alkali metals Low reactivity at room temperature 2 valence electrons Important compounds  Calcium oxide (lime) the 5 th most produced chemical  Calcium carbonate-chalk, marble, toothpaste abrasive and antacid

Group 13 Boron Family Metalloid Boron, Metal Al, Ga, In, Th Has 3 valance electrons Ions +3 Can be very hard (boron) Overall shiny, relatively soft and low melting point Can be excellent conductors (Al) Important compounds  Borax  Aluminum oxide- used in sandpaper

Group 14 The Carbon Family Non metal C, metalloid Si & Ge and metals tin and lead Has 4 valence electrons Density increases as you go down the group Hardness and melting point decrease as you go down the group Can form bonds with 4 other chemicals Important compounds  Methane CH 4  Silicon dioxide- glass  Buckminsterfullerene, nanotubes

Group 15 The Nitrogen Family Nonmetallic N, P; Metalloids arsenic, antimony (Sb) and 1 metal bismuth 5 valence electrons, ion have a -3 charge Melting points increase then decrease Density increases steadily Important compounds  Ammonia NH 3  Amino acids  Bismuth subsalicylate

Group 16 Oxygen Family Nonmetal O and S, metalloid Se and Te, lone metal polonium 6 valence electrons, has a charge of -2 Melting points increase Densities increase Important chemical  Water  H 2 S the rotten egg smell,  Hydrogen peroxide  Sulfuric acid, the cheapest strong acid

Group 17 Halogen Family Know this family Extremely reactive, F the strongest 7 valence electrons, charge of -1 Melting points increase but still well below 0 Densities increase Important compounds  HCl hydrochloric acid  Bleach NaClO  PCB discontinued as a cancer risk  Ammonium perchlorate used in the shuttle

Group 18 Noble Gases Know this family Eight valence electrons  Outer shell filled  That is why He is in this group Odorless colorless gases Unreactive  There are some exceptions

Reactivity in non metals Reactivity in metals Trends in reactivity More reactive as you move down More reactive as you move up

Atomic radius for metals increases Atomic radius for non-metals decreases Trends in atomic radius Atomic radius decreases

Least Metallic Most Reactive V8 V2 V4 Positive ions Variable v-electrons V6V5 V1 V2V3V7 Increasing reactivity Most reactive Most metallic /-4+30 Increasing reactivity Unreactive gases METALS NON-METALS METALLOIDS V8 V2 V4V6V5 V1 V2V3V7

Ion Sizes Metals form positive ions and become smaller Non-metals form negative ions and get bigger.