The Periodic Law Periodic Table of Elements video
Development of the Periodic Table • Dmitri Mendeleev developed the first periodic table • The periodic table is an arrangement of elements according to their chemical and physical properties
Mendeleev’s Periodic Table • Mendeleev arranged the elements according to their atomic masses • The elements followed a pattern of 1 2 3 4 3 2 1 (valence electrons) • video
Questions • Who developed the first periodic table? • What is the periodic table? • What are valence electrons? • How did Mendeleev arrange elements in the first periodic table?
Periodic • Refers to repeating according to a pattern
Questions • Why are the days of the week and the months of the year periodic?
Modern Periodic Tablevideo • Henry Moseley determined the atomic number of the elements • Elements in the modern periodic table are arranged according to atomic numbers • video
Periodic Law • States that the physical and chemical properties of elements are periodic functions of their atomic numbers • Properties of elements have some pattern according to their atomic numbers
Questions • What is the major difference between Mendeleev’s periodic table and the modern periodic table?
Columns in the periodic table • Columns of elements are known as groups or families • Elements in a family have similar properties
Rows in the periodic table • The horizontal rows of elements are called periods • The elements in a period do NOT have similar properties
Periods • First element in a period is an active solid • Last element in a period is an inactive gas
Questions • What is the major difference between periods and families? • How are elements in a family similar? • How are elements in a period different?
Element squares in the periodic table • The basic information found in each square of the periodic table : • Atomic number • Chemical symbol • Element name • Atomic mass • video
Elements • Elements are classified as: • Metals • Nonmetals • Metalloids
Questions • What information is found in the squares on the periodic table? • How can an element be classified?
Characteristics of Metals (video) • Good conductors of heat and electricity • Shiny; High melting points • Malleable (bends easily) • Ductile (can be made into wires) • Found on the LEFT of the periodic table
Questions • What is the difference between ductile and malleable? • Where are metals found on the periodic table?
Properties of Nonmetals • Dull • Brittle (hard/ easily broken) • Found on the RIGHT of the periodic table • video
Properties of Metalloids • Has properties of both metals and nonmetals • Found touching the dark, zig-zag line • Metalloid means “metal-like” • video
Questions • What is a metalloid? • Where are metalloids located in the periodic table? • Where are nonmetals located on the periodic table?
Periodic Properties of Elements (Modern Table) • Valence pattern across a period is 1 2 3 4 3 2 1 0 (left to right) • Metals lose electrons easily • Nonmetals gain electrons easily
Periodic Properties of Elements • The size of the atom decreases from left to right across a period • The metallic properties of elements decrease from left to right across a period • Elements on the left are more reactive than the elements on the right
Questions • What happens to metallic properties as one moves from left to right across a period? • What is the valence pattern of electrons across a period? • video