The Periodic Table Chemistry Johnson- 2014

Lesson 1

Mendeleev(mass)  Born at Tobolsk, Siberia in 1834 and died in  Mendeleev is best known for his work on the periodic table; arranging the 63 known elements into a Periodic Table based on atomic mass, which he published in Principles of Chemistry in  His first Periodic Table was compiled on the basis of arranging the elements in ascending order of atomic weight and grouping them by similarity of properties.  Mendeleev provided for variance from strict atomic weight order, left space for new elements, and predicted three yet-to-be- discovered elements including silicon and boron.

Moseley(#)

Periodic Law  PERIODIC LAW, in chemistry, law stating that many of the physical and chemical properties of the elements tend to recur in a systematic manner with increasing atomic number. Progressing from the lightest to the heaviest atoms.

Periodic Table Sublevels

Valence Electrons  Electrons in the outer energy shell of an atom.  Look at the group number of an element; the number in the 1’s position tells you how many valence electrons there are. 

Lewis Dot Diagram/Electron Dot Diagrams  Write element symbol.  Know # of valence electrons  Place dots to represent valence electrons one at a time around the element symbol clockwise starting at 12:00 until all valence electrons are present. Some of the valence electrons will end up as pairs when you are finished. 

Homework  Study note page #7.  Be able to identify the valence electrons for all main group elements (everything except transition metals).  Be able to draw Lewis Dot aka Electron Dot configurations for elements  Be able to write electron configurations for elements