Ch.5 Sec 1 and 2

Ch. 5 Sec 1

1. Periodic Table

• An arrangements of the elements in order of their atomic number so that elements w/ similar properties fall in same column or group
• Elements are arranged vertically in the P.T.(periodic table) in groups that share similar chemical properties

Ch. 5 sec. 2

Periods

• Elemts organized horizontally in rows
• Length of each period is determined by # of electrons that can occupy the sublevels being filled in that period
• The P.T. is divided in 4 blocks, s p d & f; the name of each block is chosen by the electron sublevel being filled in that block (disregarding Hydrogen and Helium b/c they are too small)

Alkali metals

• Elements of group 1 on P.T.
• Lithium, Sodium, potassium, rubidium, cesium, and francium are the Alkali metals
• In alkali metals's pure state, they all have a silvery appearance and are soft enough to cut w/ a knife

Alkaline-earth metals

• Elements in group 2 of P.T.
• Beryllium, magnesium, calcium, strontium, barium, and radium (all Alkaline-earth metals)
• Less reactive than alkali metals, but are still too reactive to be found in nature in pure form

• Hydrogen has an electron configuration of 1s1 but despite the ns2 configuration, it doesn't share the same properties as elements of group 1
• Hydrogen is an unique elments

• Like the Group 2 elements, helium has an ns2 group configurtaion, yet it is part of group 18
• B/c its highest occupied energy level is filled by 2 electrons, helium posses special chemical stability

P.S. remember to do Pre-Lab for tomorrow