Introduction to the Periodic Table. Dmitri Mendeleev The elements were first arranged in the...

Introduction to the Periodic Table

Dmitri Mendeleev

• The elements were first arranged inthe periodic table in 1869 by Dmitri Mendeleev.

• By arranging all of the 63 elements then known by their atomic weights, he managed to organize them into groups possessing similar properties. Where a gap existed in the table, he predicted a new element would one day be found and deduced its properties.

Periods

Periods are horizontal rows.

Groups

Groups are vertical columns.

Metals

Physical Properties of Metals

• Conduct heat & electricity• Malleable• Ductile• Lustrous• Almost all metals are solid at normal

temperatures.

Nonmetals

Physical Properties of Nonmetals• Brittle• Not lustrous• Poor conductors of heat & electricity• Many nonmetals are gaseous at normal temperatures (N, O, Cl, Ne)• One nonmetal is liquid at normal

temperatures (Br)• Several nonmetals are solid at normal

temperatures (C, P, S)

Metalloids or semimetals

Physical Properties of Metalloids

• Show a mixture of metallic & nonmetallic properties

• They have an intermediate level of conductivity and thus they make good semiconductors

Alkali metals

Alkali metals

• Silvery colored• They are soft, and can be easily cut with a

knife to expose a shiny surface which dulls on oxidation.

• Highly reactive• Low melting temperatures• Low boiling temperatures• Low densities

Alkaline earth metals

Alkaline earth metals

• Metals• Shiny, silvery-white color• Highly reactive

Transition metals

Transition metals

• Lustrous metallic appearance• Many of their compounds are colored• Good conductors of heat & electricity• High melting points• High boiling points

Halogens

Halogens

• All halogens exist as diatomic molecules• F2, Cl2, Br2, I2, At2

Noble Gases

Noble Gases

• Noble gases are Inert – which means that they are unreactive and do not readily combine with atoms of other elements

• Noble gases are monatomic gases• Noble gases boil at lowtemperatures

Lanthanides

Actinides