Introduction to the Introduction to the Periodic TablePeriodic Table

I. Development of the TableI. Development of the Table

A.A. Dobereiner (1829) Dobereiner (1829) placed elements in placed elements in triadstriads--groups of 3 based on similar groups of 3 based on similar characteristics.characteristics.1. When he grouped elements 1. When he grouped elements with similar properties he with similar properties he found a relationship with found a relationship with atomic mass.atomic mass.

Halogen TriadHalogen Triad

ElemenElementt

Symbol Symbol Atomic Atomic massmass

ChlorinChlorinee

ClCl 35.535.5

BrominBrominee

BrBr 8080

IodineIodine II 127127

These 3 elements have similar properties.

(35.5 + 127)/2 = 81.2

B. Mendeleev (1869)B. Mendeleev (1869)

1.1. Arranged elements by Arranged elements by increasing atomic mass in increasing atomic mass in columns, starting with the columns, starting with the lightest.lightest.

Mendeleev’s Periodic TableMendeleev’s Periodic Table

3.3. Significance of Mendeleev’s tableSignificance of Mendeleev’s table Showed that element properties Showed that element properties

display display periodicityperiodicity-the tendency to -the tendency to recur at regular intervalsrecur at regular intervals

He predicted the properties of He predicted the properties of several undiscovered elements. several undiscovered elements. (blank spaces)(blank spaces)

Ex: TelluriumEx: Tellurium

C. Moseley & The Modern Periodic C. Moseley & The Modern Periodic TableTable

1.1. Rearranged the periodic Rearranged the periodic table by increasing atomic table by increasing atomic numbernumber

2.2. Periodic Law-Periodic Law-

physical & chem properties physical & chem properties of elements repeat in a of elements repeat in a regular pattern when regular pattern when arranged in order of arranged in order of increasing atomic #increasing atomic #

Ex: atomic radiusEx: atomic radius

II. Using the Periodic II. Using the Periodic TableTable

A.A. PeriodPeriod- horizontal row- horizontal row

B.B. Group (family)-Group (family)- vertical column vertical column members of the same family have the members of the same family have the

same # valence esame # valence e--

They have similar chem propertiesThey have similar chem properties

C. The Groups of the Periodic C. The Groups of the Periodic TableTable

Group 1: Alkali MetalsGroup 1: Alkali Metals

1 valence1 valenceThe most reactive elementsThe most reactive elementsNever found uncombined in natureNever found uncombined in natureSoft, shiny metalsSoft, shiny metalsNa is so reactive it must be packaged Na is so reactive it must be packaged

in oilin oil

Na

Group 2: Alkaline Earth Group 2: Alkaline Earth MetalsMetals

2 valence2 valence22ndnd most reactive elements most reactive elementsNever found uncombinedNever found uncombined

Transition MetalsTransition Metals

Found in the middle of the periodic Found in the middle of the periodic tabletable

Don’t always have the same # Don’t always have the same # valencevalence

Example: Sometimes Cu has 1 Example: Sometimes Cu has 1 valence and sometimes it has 2.valence and sometimes it has 2.

Group 13: Boron FamilyGroup 13: Boron Family

3 valence3 valenceB is a metalloid, the rest are metalsB is a metalloid, the rest are metalsEx: AlEx: Al

Group 14: The C familyGroup 14: The C family

4 valence4 valenceC is so abundant it has a whole C is so abundant it has a whole

branch of chemistry called branch of chemistry called organic organic chemistrychemistry

Si is in glass, cement, computer Si is in glass, cement, computer chipschips

Sn & PbSn & Pb

Group 15: Then N familyGroup 15: Then N family

5 valence5 valenceNN22 makes up 78% of the atmosphere makes up 78% of the atmosphereN & P are used as fertilizer and are N & P are used as fertilizer and are

cycledcycledAs As

Group 16: The O familyGroup 16: The O family

6 valence6 valenceO is very reactiveO is very reactiveEx: SEx: S

Family 17: The HalogensFamily 17: The Halogens7 valence7 valenceMost reactive nonmetalsMost reactive nonmetalsForm salts when they react with Form salts when they react with

metalsmetals

Ex: NaClEx: NaClUsually gain 1 e Usually gain 1 e Ex: Cl & IEx: Cl & I

Family 18: Noble GasesFamily 18: Noble Gases

Have full valenceHave full valenceMost stable elementsMost stable elementsEx: He, NeEx: He, Ne

Rare Earth Metals found at Rare Earth Metals found at bottombottom

Lanthanide seriesLanthanide seriesActinide seriesActinide series

RadioactiveRadioactiveMost don’t occur in natureMost don’t occur in nature

Enriched Uranium

D. Physical State & Classes of D. Physical State & Classes of ElementsElements

1.1. Physical StatesPhysical States

a. Most elements are solida. Most elements are solid

b. 2 liquids = Br & Hgb. 2 liquids = Br & Hg

c. All gases are in the upper right c. All gases are in the upper right except H.except H.

Br

2.2. Metals, nonmetals & metalloidsMetals, nonmetals & metalloidsa. Most elements are metalsa. Most elements are metals

MetalsMetals

1.1. Have lusterHave luster

2.2. High melting ptHigh melting pt

3.3. Conduct heat & electricityConduct heat & electricity

4.4. MalleableMalleable

5.5. DuctileDuctile

6.6. Solid at room temp except Solid at room temp except HgHg

7.7. Lose e when they bondLose e when they bond

8. Are subject to 8. Are subject to corrosioncorrosion – –

the deterioration of a material as a the deterioration of a material as a result of reaction with its result of reaction with its environment, especially with oxygen environment, especially with oxygen

NonmetalsNonmetals

Opposite of metals in all propertiesOpposite of metals in all propertiesAre brittleAre brittleAre often insulatorsAre often insulatorsShare or gain electrons when they Share or gain electrons when they

bondbondMany are gasesMany are gases

MetalloidsMetalloidsHave characteristics between a Have characteristics between a

metal & a nonmetal.metal & a nonmetal.Are Are semiconductorssemiconductors- conduct heat & - conduct heat &

electricity, but not as good as a electricity, but not as good as a metalmetal

Ex: SiliconEx: Silicon