TOIPC: Periodic Table Organization

Do Now: take new packet and open up to blank periodic table

Periodic Law

• There is a periodic repetition of chemical and physical properties of elements when arranged by increasing atomic number

The periodic table hasn’t always look like this

History of the Periodic Table

• End of the 1700’s – less than 30 elements known

• Many elements discovered during 1800’s

• Many experiments done to determine atomic masses

http://www.dlt.ncssm.edu/TIGER/chem1.htm

John Newlands

• 1864: if elements arranged by atomic mass - properties repeat every 8th element

• Law of Octaves – did not work for all known elements

• Key idea was correct: Properties of elements do repeat in periodic way

Mendeleev & MeyerMendeleev produced 1st accepted PT: 1869•Elements ordered by ↑ atomic mass into columns with similar properties•Predicted existence & properties of undiscovered elements•Not totally correct

– more accurate atomic mass calculations showed some elements weren’t in right place

Remember

1860’s:

•No subatomic particles yet discovered

•Dalton’s billiard ball model of the atom

1913 – Henry Moseley

• by 1913, protons & electrons discovered– Neutrons were predicted

• Moseley determined atoms of each element contain unique # protons (= atomic number)

• rearranged Mendeleev’s PT by atomic number instead of mass

• problems with elements in wrong place disappeared

http://library.tedankara.k12.tr/chemistry/vol1/atomstr/trans50.jpg

Periodic Table is arranged according atomic number and organized into groups and periods

COLUMNSGroups/Family numbering (1 18) left to right

TELL US NUMBER OF VALENCE ELECTRONS (KIND OF)

Valence Electrons – electrons in the outer shell

• Chemical behaviour determined by # valence electrons

• Elements with same # valence electrons will have similar chemical properties

–Elements in same column have similar chemical properties

Going Down Column 1:

2-8-18-32-18-8-1Fr7

2-8-18-18-8-1Cs6

2-8-18-8-1Rb5

2-8-8-1K4

2-8-1Na3

2-1Li2

1H1

ConfigurationElementPeriod

Valence Electrons

414 or IVA

313 or IIIA

22 or IIA

11 or IA

Number of Valence Electrons

Group

Names of Families(AKA group A elements)

• Group 1 = Alkali Metals

• Group 2 = Alkaline Earth Metals

• Groups 3-12: Transition metals

• Group 17 = Halogens

• Group 18 = Noble Gases

Transition Metals (in yellow)

• Groups 3 through 12

form brightly colored salts

Inner Transition Metals

• Lanthanide (rare Earth metals) – can be found naturally on Earth, only 1 is radioactive

• Actinide– all are radioactive, some are made in the lab. INCLUDES Uranium

ROWSPeriod numbering (1 7) top to bottom

TELL US NUMBER OF SHELLS (energy levels)

Energy Levels = Row Number• Elements in same row

have same # of principal energy levels