Applied Chem. C3 Notes

Development of the Periodic Table

C3 Section 1 Vocabulary

• Periodicity• Periodic Law

C3-1: Search for a Periodic Table

• 1829 JW Dobereiner (old German guy)– Classified elements into 3 groups• Triads

– Similar properties

Mendeleev’s Periodic Table

• 1869 Russian Chemist• Studied properties of elements• Arranged elements in repeating pattern of

increasing atomic mass

Mendeleev’s Table:

Why this Mendeleev’s table is special!

• Periodicity: Tendency to recur at regular intervals.

• Mendeleev correctly predicted the properties of several undiscovered elements.

• Left blank spaces for undiscovered elements• Formed basis for modern periodic table

Modern Periodic Table

Characteristics of Modern PT

• Arranged by atomic number and not atomic mass.– Find where the atomic number increases but

atomic mass decreases.

• Periods (rows)• Groups (columns)

Periodic Law

• Physical and chemical properties of the elements repeat in a regular pattern when they are arranged in order of increasing atomic number

C3 Section 2 Vocabulary

• Period Metalloid• Group Semiconductor• Noble Gas• Metal• Transition metal• Lanthanide• Actinide• Nonmetal

C1 Section 2: Using the Periodic Table

• Periods (rows)– Represent the energy levels electrons can occupy.– Each new period has a new energy level

• Groups (columns)– Sometimes called a family– All elements in a group have similar properties

Names of Groups

Physical States and Classes of Elements

• Metals are elements that have luster, conduct heat and electricity, and usually bend without breaking

• Majority of elements

Where are metals located on periodic table?

Transition metals

• Elements in groups 3-12• Commonplace: Silver (Ag), Copper (Cu), Iron

(Fe), Zinc (Zn)• Some radioactive• Not as predictable in properties as main group

elements

Inner Transition Metals

• Lanthanides=Atomic numbers 57 (Lanthanum) to 71.– Not naturally abundant on earth– Called “rare earth”– All lanthanides have similar properties

• Actinides=Atomic numbers 90-103– Unpredictable properties

Characteristics of Nonmetals

• Many nonmetals are abundant in nature.• Examples include oxygen and nitrogen that

make of 99% of atmosphere.• Don’t conduct electricity.• Poor conductors of heat.• Brittle when solid.• Many nonmetals are gases at room

temperature.

Metalloids

• Some properties of metals and some properties of nonmetals

• Lie between the border of metals and nonmetals

• Some metalloids are semiconductors

• Silicon (Si), germanium (Ge) and arsenic (As) are metalloids that are semiconductors.

• Look at your phone for uses of semiconductors!

Electrical Conduction of Semiconductor

Doped Semiconductors