Periodic Table of the Elements

Periodic Table of the Elements Suggested Reading Pages 133-149 Section 5-1 & 5-2

Early Development of P.T. • 1700’s – about 30 elements identified • Antoine Lavoisier • Antoine Lavoisier's Traité Élémentaire de Chimie, 1789, as quoted in J. R. Partington's A Short History of Chemistry (Dover, 1989, ISBN 0486659771).

Early 1800’s • J.W. Dobereiner • Triads (groups of 3) • Similar Properties • Mass of middle element was close to the average of the other two in the triad.

1865 • J.A.R. Newlands • 62 elements arranged by atomic mass • Similar Properties with every 8th element • Law of Octaves

1869 • Dmitri Mendeleev – 1st periodic table. • Arranged by atomic mass & how one element reacted with other elements. • Left gaps for undiscovered elements.

Mendeleev’s Periodic Table

Henry Moseley 1913 • Determined the nuclear charge of the atom. • Modified Mendeleev’s P.T. • Arranged elements by increasing atomic number.

Modern Periodic Table • Elements are arranged in order of increasing atomic number so that elements with similar properties fall in the same column.

Periodic Law • The physical and chemical properties of the elements are periodic functions of their atomic numbers. • When elements are arranged in order of increasing atomic number, elements with similar properties appear at regular intervals.

Organizing the Squares • Metals • Nonmetals • Metalloids • Groups – Vertical • Groups have similar chemical and physical properties. • Periods – Horizontal Rows

Group Labels • Representative Elements • Transition Metals • Inner Transition Metals – Lanthanide & Actinide Series

Group Names • Alkali Metals • Alkaline Earth Metals • Halogens • Noble Gases

“Blocks” s-block d-block p-block f-block

Electron Configuration • Valence electrons – responsible for properties of elements. • Same groups = similar electron configurations = similar properties

Representative elements • Outermost s & p sublevels are only partially filled. • Group # tells you how many valence electrons there are. 8A 1A 2A 3A 7A 4A 6A 5A

s-Block • Chemically Reactive Metals • Group 1 – Alkali Metals (most reactive) Soft, silvery, can be cut with a knife. • Group 2 – Alkali Earth Metals (harder, denser, stronger than alkali metals). • Too reactive to be found in nature as free elements.

p-block • Main group elements • All nonmetals (except H) • All metalloids • Halogens – most reactive nonmetals. • Noble Gases - inert

Transition Metals • Outermost s sublevel and nearby d sublevel contain electrons. Transition Metals

d-block • Metals with typical “metal” properties … gold, silver, etc. • Transition elements • Fairly unreactive • Some exist in nature as free elements

Noble Gases • Outermost s & p sublevels are filled. • Inert Gases (do not readily react).

Hydrogen and Helium • Hydrogen is unique – does not fit in with any group. • Helium fits in best with group 18 because its highest energy level is full and it is nonreactive or inert.

*Inner Transition Metals • Outermost s sublevel and nearby f sublevel contain electrons. Inner Transition Metals

f-block • Lanthanides and Actinides • Lanthanides – shiny metals similar in reactivity to alkaline earth metals. • Actinides – all are radioactive

Periodic Table of the Elements

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