# Unit II—Part 4 Adapted by NCDPI – Unit 2 Matter all around us

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Unit II—Part 4 Adapted by NCDPI – Unit 2 Matter all around us
The Periodic Table Unit II—Part 4 Adapted by NCDPI – Unit 2 Matter all around us

The Father of the Periodic Table—Dimitri Mendeleev
Mendeleev was the first scientist to notice the relationship between the elements Arranged his periodic table by atomic mass Said properties of unknown elements could be predicted by the properties of elements around the missing element Image taken from:

Henry Moseley Moseley later discovered that the periodic nature of the elements was associated with atomic number, not atomic mass Image taken from:

The Periodic Table Column = Group or Family
18 columns on the Periodic Table Row = Period 7 rows on the Periodic Table

Periods •Each row is called a “period”
•The elements in each period have the same number of energy levels 1st Period = 1 E. Level 2nd Period = 2 E. Levels 3rd Period = 3 E. Levels 4th Period = 4 E. Levels 5th Period = 5 E. Levels 6th Period = 6 E. Levels 7th Period = 7 E. Levels Middle School Science Image: Chem4kids.com

Groups •Each column is called a “group”
•Each element in a group has the same number of electrons in their outermost energy level (valence electrons) Except for He, it has 2 electrons Group 1 = 1 electron Group 2 = 2 electrons 4 Group 8 = 8 electrons Middle School Science Image: Chem4kids.com

Metals, Nonmetals, and Semi-metals
Only nonmetal on the metal side Nonmetals are on the right of the stair-step Metals are to the left of the stair- step Semi-metals, “metalloids,” touch the stair-step

Special Rows on the PT Lanthanides Actinides

What does the information in the box tell me?
1 H 1.008 Atomic Number = # of protons Elemental Symbol Atomic Mass = # of protons plus neutrons

The Groups of the Periodic Table
Group 1: The Alkali Metals Most reactive metals on the PT Rarely found free in nature Charge of 1—1 valence electron 87 Fr (223) 55 Cs 37 Rb 85.468 19 K 39.098 11 Na 22.990 3 Li 6.941 1 H 1.008 + -

The Groups of the Periodic Table
Group 2: The Alkaline Earth Metals Still quite reactive Charge of 2—2 valence electrons Image: Chem4kids.com Image:

T he Groups of the Periodic Table
Groups 3-12: Transition Metals Found freely and in compounds in nature Charge is usually 2 but can vary—usually 2 valence electrons Group 13: Boron Family Charge is 3—3 valence electrons

The Groups of the Periodic Table
Group 14: The Carbon Family Contains elements that can form unusual bonds (carbon and silicon) Charge is +4 or -4—contains 4 valence electrons Group 15: The Nitrogen Family Charge is -3—contains 5 valence electrons

The Groups of the Periodic Table
Group 16: The Oxygen Family Also known as the chalcogens Charge is -2 has 6 valence electrons Group 17: The Halogens Most reactive nonmetals charge is -1 has 7 valence electrons Group 18: The Noble Gases (The Inert Gases) Nonreactive Charge is 0—2 or 8 valence electrons