Chapter 3 The Periodic Table

Development of the Modern Periodic Table J.W. Döbereiner Classified some elements into groups of three, which he called triads Elements in a triad had similar chemical properties, and their physical properties varied in an orderly way according to their atomic masses

Development of the Modern Periodic Table John Newlands Arranged elements by increasing atomic mass Their properties repeated every 8th element Known as the law of octaves

Development of the Modern Periodic Table Dmitri Mendeleev Demonstrated a connection between atomic mass and elemental properties Arranged elements in order of increasing atomic mass Predicted the existence and properties of undiscovered elements Based his table on 60 or so elements

Development of the Modern Periodic Table Henry Moseley Discovered that atoms contain a unique number of protons called the atomic number Arranged elements in order of increasing atomic number, which resulted in a periodic pattern of properties

The Modern Periodic Table Arranged in order of increasing atomic number which increases as you move across rows called periods Elements with similar chemical properties appear in the same column called groups Properties change in an orderly progression across the rows from left to right

Periodic law The physical and chemical properties of the elements repeat in a regular pattern when they are arranged in order of increasing atomic number

Types of Elements Metals Nonmetals Generally shiny when smooth and clean Solid at room temperature Good conductors of heat and electricity Malleable and ductile Loosely held valence electrons Have high melting points Generally gases at room temperature Brittle, dull-looking solids Poor conductors of heat and electricity Tightly held valence electrons Lower melting points than metals

Types of Elements Metalloids Have physical and chemical properties of both metals and nonmetals Also called semimetals and semiconductors Lie along the border between metals and nonmetals

Groups of Elements Group 1 Alkali metals Group 2 Alkaline earth metals 1st Row Lanthanide Series (Lanthanoid) 2nd Row Actinide Series (Actinoid) Group 16 Chalcogens (Oxygen Group) Group 17 Halogens Group 18 Noble gases Groups 3-12 Transition Elements (Metals)