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 PeriodMetalloid GroupSemiconductor 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 – 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