Tuesday, Oct 10  You have a CBA tomorrow!  Follow the power point to fill in your chart  Tape it on p. 30 when you are done  Work on your CBA review sheet  I will be here after school if you have any questions

The Periodic Table History of the Periodic Table The Periodic Table

Why is the periodic table important to me?  The periodic table is the most important tool for chemists.  You get to use it on every test.  It organizes lots of information about all the known elements.

Mendeleev – the father of the periodic table  Dmitri Mendeleev (1869, Russian)  Organized elements in rows by increasing atomic mass.  Elements with similar properties were grouped together in the same column  There were some discrepancies- some elements didn’t quite match up.

Moseley  Henry Moseley (1913, British)  Organized elements by increasing atomic number.  Resolved discrepancies in Mendeleev’s arrangement.  Periodic Law-the physical and chemical properties of the elements are periodic functions of the atomic numbers.

Periodic Table  Periodic table-an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column, or group.

Horizontal rows of the periodic table are called PERIODS. Each element in the period is in the same energy level.

Vertical columns of the periodic table are called GROUPS or FAMILIES.

Groups  The elements in any group of the periodic table have similar chemical and physical properties, because they have the same number of valence electrons.

Group 1: Alkali Metals  1 valence electron  Silvery appearance and very soft (can be cut with a butter knife)  Not found pure naturally because so reactive  All the alkali metals react vigorously or explosively with water  Because of extreme reactivity with moisture, usually stored in oil

Group 1

Group 1 Video  Nv3swDk Nv3swDk  Sodium (Na) reacting with water

Group 2: Alkaline Earth Metals  2 valence electrons  Harder, denser, & stronger than alkali metals  Shiny and silvery white appearance  Do not dissolve well, hence “earth metals”  Also too reactive to be found free in nature (but less reactive than Group 1)

Groups 3-12: Transition Metals  Valence electrons vary  Metals with typical metallic properties  Properties of metal include luster, good thermal and electrical conductivity, and the capability of being permanently shaped or deformed at room temperature. (malleable and ductile) Called “transition elements”  Typically less reactive than Groups 1&2, & some are extremely unreactive

Groups  Contains: metals, nonmetals, and metalloids  Properties vary  Total number of electrons in highest energy level = group # - 10  Ex. Group 13 elements have 13-10= 3 “valence” electrons  Group 14= 4 valence electrons, Group 15= 5 valence electrons, etc

Metalloids  Fall on both sides of a “stair-step” line separating metals and nonmetals  Sometimes behave like a metal and at other times like a nonmetal.  Some examples of metalloids are: boron, silicon, germanium, etc.

Group 17: Halogens  Nonmetals with 7 valence electrons  Common properties considered characteristic of a nonmetal include: poor conductors of heat and electricity. In solid form, they are dull and brittle. They usually have lower densities than metals.  Most reactive nonmetals  React with most metals to form salts (NaCl, KCl, MgCl 2, etc)

Group 18: Noble Gases  “ Nobility of the periodic table”  8 valence electrons WITH the exception of Helium  VERY unreactive and extremely stable because they have 8 valence electrons  All gases at room temperature  Don’t bond with other elements

Lanthanides & Actinides  Lanthanides  Top row of f-block  14 elements  Shiny metals similar in reactivity to the alkaline-earth metals  Actinides  Bottom row of f-block  14 elements  All radioactive  1 st 4 elements found naturally on Earth; remainder only lab-made elements

 Take your I-Journal and your review sheet to study for your TEST tomorrow!!!  I will be here after school, stop by if you need help with anything!