Periodic Table

History Antoine Lavoisier – Father of Modern Chemistry 1829 German J. W. Dobereiner Grouped elements into triads Three elements with similar properties Properties followed a pattern The same element was in the middle of all trends Not all elements had triads

Law of Octaves 1862 John Newlands developed Law of Octaves The elements showed a repetition in their chemical properties after 8 elements Used Atomic Weights but not actual values Important because showed the first pattern of repeating properties

Julius Lothar Meyer Meyer first table published 1864 containing 28 elements Arranged in order of Atomic Weight and made a clear horizontal relationship Allowed properties (valency) to outweigh Atomic Weight Anticipated Mendeleev by years

Meyer Left gaps to denote unknown elements Not willing to make predicitions More focused on Physical properties not chemical properties Bitter battle with Mendeleev Lost to Mendeleev because of Mendeleev’s forceful ways

History Russian scientist Dmitri Mendeleev taught chemistry in terms of properties Mid 1800 – atomic masses of elements were known Wrote down the elements in order of increasing mass Found a pattern of repeating properties Not first to develop system but his version had the strongest impact

Mendeleev’s Table Grouped elements in columns by similar properties in order of increasing atomic mass Found some inconsistencies - felt that the properties were more important than the mass, so switched order. Found some gaps Must be undiscovered elements Predicted their properties before they were found

Dmitri Mendeleyev Mendeleyev was known as the “Father of the Periodic Table” DOB: 1834-1907 Created the first table on 3-1-1869 Table had 70 elements Used properties to set up table

Mendeleev Distinguished from competitors by a devotion to, and love for, the individuality of the elements that went hand in hand with an intimate knowledge of their chemical characteristics Focused on both physical and chemical properties

Mendeleyev Cont. Properties Used: Atomic Weight Melting Pts. Densites He could only predict these properties His work preceded chemical advances by 30 years Produced his table 27 years before the first subatomic particle, the electron was discovered Did not predict Noble Gases

Acceptance Mendeleev’s table received real acceptance in 1875 Discovery of Scandium, Germanium and Gallium showed Mendeleev’s predictions were correct.

“The elements were not being arranged to make a periodic table, but to fit the periodic table”

Meyer vs. Mendeleyev Julius Meyer (1830-1895) Created a table that plotted: Atomic Volume vs. Atomic Weight Lost out to Mendeleyev Published before Meyer Final Table: Atomic Weight vs. Valency Table had 8 columns but was missing Noble Gases Discovered 30 years later

Modern Russian Table

Spiral Periodic Table

Changing of Table Henry Moseley (1887-1915) – changed table in 1913 by increasing atomic number Currently use this today Glenn Seaborg – rare earth series from Actinium (89) up. Minor Changes – inner transitional Lu & Lr replaced La & Ac Bohr first linked Quantum Theory

Today’s Table

More History First Classified Groups: Gases Non-Metals Metals Earths First Elements Discovered: Carbon Sulfur Copper Gold & Silver Iron Tin Antimony Mercury Lead Oxygen (1772) First Classified Groups: Gases Non-Metals Metals Earths

The elements in the A groups are called the representative elements

Transition metals The Group B elements

IA IIA IIIB IVB VB VIB VIIB VIIIB IIIA IVA VA VIA VIIA VIIIA IB IIB 1 Other Systems IA IIA IIIB IVB VB VIB VIIB VIIIB IIIA IVA VA VIA VIIA VIIIA IB IIB 1 2 13 14 15 16 17 18 3 4 5 6 7 8 9 10 11 12 1A 2A 3A 4A 5A 6A 7A 8A 3B 4B 5B 6B 7B 8B 1B 2B

Vertical Columns Known as Groups or a Family Elements in same group have similar physical & chemical properties Each group is identified by a group number and group letter

Horizontal rows are called periods There are 7 periods

Group 1A are the alkali metals Group 2A are the alkaline earth metals

Group 7A is called the Halogens Group 8 are the noble gases

The group B are called the transition elements These are called the inner transition elements and they belong here

Metals

Metals & Their Properties Metals are good conductors of heat and electricity Metals are malleable Metals have high luster

Example of Metals Copper is a relatively soft metal and a very good electrical conductor Mercury is the only metal that exists as a liquid at room temperature

Non-metals

Nonmetals & Their Properties Carbon, the graphite in a pencil is an example of a nonmetallic elements Nonmetals are poor conductors of electricity Can be brittle Non-lustrous Many are gases at room temperature

Example of Nonmetals Sulfur was once known as Brimstone Microspheres of phosphorus, a reactive nonmetal

Metalloids or Semimetals Properties of both Semiconductors

Example of a Metalloid Silicon is a metalloid Silicon is brittle like a nonmetal Silicon has metallic luster Silicon is a semiconductor of electricity