Introduction to the Periodic Table

Introduction to the Periodic Table

History of Periodic Table

Basic chemical elements known since prehistoric times Easy to mine with simple tools. Gold Silver CopperWhy? Exist in native form (no processing needed).History of Periodic Table

Science has come along way since Aristotles theory of Air, Water, Fire, and Earth (300B.C.).

In 1669, 1st element discovered through scientific enquiry was phosphorus, P.

History of Periodic Table

urineHennig Brand (and later Robert Boyle) turned urine into P! Ewww!History of Periodic TableElements Song 1Scientists have identified 90 naturally occurring elements, and created about 28 others (present total 118).History of Periodic TableSo how and why are the elements organized as they are?

Li36.941Elements in Periodic TableLi36.941solidAtomic number = protons an atom of that element has.

The atomic number is unique to that element. No two elements have the same atomic number.Atomic NumberInformation for Elements in the Periodic Table

State of matter at room temperature

Atomic mass = protons and neutrons an atom of that element has (round to nearest whole number, so Li = 7)

LithiumChemical Symbol

Chemical Name

Bohr Model of Atom

Niels Bohr proposed the Bohr Model of the Atom in 1915.C6Carbonpositively-charged nucleus orbited by negatively-charged electrons.Electrons orbit around the nucleus in different energy levels lowest energy level nearest to nucleus.1st energy level2nd energy levelSubatomic Structure and Bohr Model of Atom

Li37

1 outer electron in 2nd electron shell2 electrons (max.) in 1st electron shellElectron configuration for Li, 3 electrons = 2, 1

Kids to practice a few elements with magnetic Bohr modelTry Helium (at # 2, mass 4) Beryllium (at # 4, mass 9) and magnesium (at # 12 mass 24)How is reactivity of an element related to its position in the Periodic Table?

All elements want to be stable and have full outer electron shell (2 electrons for 1st shell, 8 electrons for outer shells)

Elements either try to lose an electron or gain one, whichever is easier energetically

3+lose!Li9+gain!F

Reactivity Increases DOWN a groupReactivity decreases and then increases across periodNon-reactive (inert) elements3+11+LiLithium: 3P, 3e (2,1)NaSodium: 11P, 11e (2, 8, 1)Single outer electron far from nucleus, shielded by electron cloud and easily lost, therefore Na more reactive than LiSingle outer electron closer to positive nucleus than atoms further down the group with more electron shells therefore not as reactiveReactivity Increases going DOWN a group

3+Lose 1 electron!Li5+BF5+Gain 1 electron!Reactivity decreases and then increases across periodNeeds 3 more electrons to get stable full shell of 8Meet the Elements They Might Be Giants

11 (atomic number)Na (11 N 12 e 11t symbol)23 (atomic mass)Sodium (element name)A11 (atomic number)Na (element symbol)23 (atomic mass)Sodium (element name)

SLG P 11 N 12 e 11Bohr model2, 8, 1 electron arrangementYour work!Li37 P 3 N 4 e 3 S L GBohr modelElectron configuration2,1 lithium