Chemistry

Chapter 6The Periodic Table

The Periodic Table

• Developed by DimitriMendeleev in 1869

• Arranges the elements by similarities in their chemicalproperties

• Each element has a unique symbol and atomic number

The 1st Periodic Table

Metals v. Nonmetals

Example

Classify the following elements as metals or nonmentals.Bromine TungstenMagnesium PhosphorusMercury LithiumHydrogen Neon

Electron Configurations

• The periodic table is arranged by electron configurations

• Unknown to Mendeleev and Moseley• Elements with the same electron

configuration in the outer energy level are in the same groups

Transition Metals

• These are the d-block and f-block metals• Form colored compounds• Typically are more dense, and have higher

melting and boiling points than s-block metals

Noble Gases

• The last group discovered because of inertness

• In 1895 argon was successfully isolated from air

• Soon after other noble gases were isolated and they were added to the periodic table

Alkali Metals• All highly reactive and are never

found in elemental form in nature • Soft metals• React readily with water to form

bases• All electron configurations end with

ns1

Alkaline Earth Metals• Much less reactive than alkali

metals• Soft metals• Can be made to react with water to

form bases• All electron configurations end with

ns2

Halogens• Most reactive nonmetals• Are all found as diatomic molecules

in their pure form• Contain gases, a liquid, and solids• All electron configurations end with

ns2np5

Example

Classify the following elements as alkali metals, alkaline earth metals, transition metals, halogens, or noble gases.BromineMagnesiumMercuryLithium NeonTungsten

HalogenAlkaline Earth MetalTransition MetalAlkali MetalNoble GasTransition Metal