Organizing the Elements

Ch. 3 Sec. 2

Activity-Which is easier? Pg. 80Your time (seconds)

RANDOM ORDER

Your time (seconds)

ROWS

Why is the Periodic Why is the Periodic Table important to me?Table important to me?

most useful tool to a chemist

organizes lots of info. about all known elements

Pre-Periodic Table Chemistry … …was a mess!!! No organization of elements. Imagine going to a grocery

store with no organization!! Difficult to find information. Chemistry didn’t make sense.

Dmitri Mendeleev: Father of the Table

HOW HIS WORKED…

Put elements in rows by increasing atomic mass.

Put elements in columns by the way they reacted.

SOME PROBLEMS… He left blank spaces for

what he said were undiscovered elements. (Turned out he was right!)

He broke the pattern of increasing atomic weight to keep similar reacting elements together.

The Current Periodic Table Mendeleev wasn’t too far off. Now the elements are put in

rows by increasing ATOMIC NUMBER!!

Each square of periodic table incl:

element’s atomic number= # of protons in its nucleus

chemical symbol name atomic mass= avg. mass of

all isotopes of that element15.9994

Chemical symbol 1 or 2 letters ex: iron= Fe

Groups

columns aka families 18 groups eg: Group 15= nitrogen family each group has similar characteristics

Periods Horizontal rows 7 periods

Periodic Table Song by Tom Lehrer

YouTube video-Meet the Elements

Periodic Table Rap-YouTube http://www.youtube.com/watch?

v=cAnOUwPfHlk&feature=related