The Periodic Table Ch. 6

Why is the Periodic Table so important to chemists?

Three Classes of Elements

Groups  Elements in the same group have similar chemical and physical properties Why??

Families  Columns are also grouped into families  Families may be one column or several  Families have names rather than numbers

Hydrogen  A family of its own  Diatomic  Reactive gas

Alkali Metals  Group 1A (No hydrogen)  Very reactive metals  Always combined with something else in nature  Soft metals

Alkaline Earth Metals Group 2A Reactive metals Always combined with nonmetals in nature Some are important mineral nutrients (Mg and Ca)

Transition Metals d-Block elements Less reactive harder metals Includes metals used in jewelry and construction Cannot easily predict valence e -

Carbon Family  Elements in group 4A  Branch of chemistry based on Carbon  Silicon and Germanium are important semiconductors

Halogens  Group 7A  Reactive  Volatile  Diatomic (F 2,Cl 2,Br 2,I 2 )  Nonmetals  Always found combined with other elements in nature

The Noble Gases  Group 8A  Unreactive gases (Inert)  Have a full valence shell

- Have f orbitals that contain electrons -Used to be called rare-earth elements -More abundant than other metals Inner Transition Metals

 Groups 1A – 7A Representative Elements