Periodic Table of Elements The Periodic Law Periodic Table of Elements

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-, 0 (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 Table video 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?

Summary Slide Periodic Properties of Elements (Modern Table)

Periodic Properties of Elements (Modern Table) Valence pattern across a period is: First 4 columns lose 1 2 3 4 Last 4 columns gain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