The Historical Development of the Periodic Table 1790s

The

Historical Development of the Periodic Table • 1790’s --- French scientist Antoine Lavoisier compiled a list of elements known at the time. • Many of the elements such as gold, carbon, and oxygen were known since prehistoric times.

Historical Development of the Periodic Table -- continued • 1864 ---John Newlands, an English chemist proposed an organization scheme for the known elements. • He noticed that when elements were arranged by atomic mass, their properties repeated every eighth element. • The first and the eighth elements had similar properties.

Historical Development of the Periodic Table -- continued • 1869 --- Lothen Meyer (a German chemist) & Dimitri Mendeleev ( a Russian chemist) • Organized elements by increasing atomic mass into columns with similar properties • Predicted the existence and properties of undiscovered elements.

The Modern Periodic Table Groups (sometimes called Families) • Are columns numbered from 1 -8, followed by a letter “A” or “B” • “REPRESENTATIVE ELEMENTS” • The groups designated with a letter “A” (1 A to 8 A) • “TRANSITION ELEMENTS” • The groups designated with a “B” (1 B through 8 B) are referred to as the • A more recent numbering system • uses the numbers 1 through 18 (also appears above each group)

The Modern Periodic Table --- continued • Period ( rows on the periodic table) • The periodic table consists of rows called Periods • There a total of 7 rows or periods, beginning with hydrogen • These rows also designate the energy level where electrons are found (more about this when we talk about electron configuration).

The Modern Periodic Table --Classifying the Elements • Metals • • Generally shiny when smooth and clean Solid at room temperature Good conductors of heat and electricity Most metals are ductile (drawn into wires) and malleable (moldable). Metals are in green

The Modern Periodic Table --Classifying the Elements • Nonmetals • • Elements that are generally gases or brittle Dull-looking solids They are poor conductors of electricity The only nonmetal that is a liquid at room temperature is Bromine Non metals are in orange

The Modern Periodic Table --Classifying the Elements • Metalloids • Elements with physical and chemical properties of both metals and nonmetals Metalloids are in purple

THE REPRESENTATIVE ELEMENTS Group 1 A – The Alkali Metals • Elements have 1 valence electron • Lose their valence electron = +1 charged ion • Good conductors of heat and electricity • Highly reactivity (The most reactive) • Silver in color • Belong to the s-block in the periodic table

THE REPRESENTATIVE ELEMENTS Group 2 A – The Alkaline Earth Metals • have 2 valence electrons • Lose their valence electrons = +2 charged ion • Less reactive than alkali metals • Most compounds of alkaline earth metals do not dissolve easily in water • Belong to the s-block in the periodic table

THE REPRESENTATIVE ELEMENTS Group 3 A – The Boron Group • Named for the metalloid Boron • Elements have 3 valence electrons • Lose their valence electrons = +3 charged ion • Most often found as oxides in the earth’s crust • Boron is the only metalloid in this family, all other elements are metals • Belong to the p-block in the periodic table

THE REPRESENTATIVE ELEMENTS Group 4 A – The Carbon Group • Is named for the nonmetal Carbon • Elements have 4 valence electrons • Lose their valence electrons to form a +4 charged ion OR can gain 4 electrons and form a – 4 charged ion • Contains all three classifications: nonmetals, metalloids, and metals • Belong to the p-block in the periodic table.

THE REPRESENTATIVE ELEMENTS Group 5 A – The Nitrogen Group • Is named for the nonmetal Nitrogen • Elements have 5 valence electrons • Gain 3 electrons = -3 charged ion – Except Bismuth, which can lose 3 electrons and form ions with a +3 charge • Contains all three classifications: nonmetals, metalloids, and a metal • Nitrogen essential for life, being part of DNA – Liquid N 2 used as refrigerant: preservation of biological samples • Belong to the p-block in the periodic table

THE REPRESENTATIVE ELEMENTS Group 6 A – The Oxygen Group • Is named for the nonmetal Oxygen • Elements have 6 valence electrons • Gain 2 electrons = -2 charged ion • Contains all three classifications: nonmetals, metalloids, a metal • O 2 is the 3 rd most abundant in the universe – No combustion without oxygenation • Belong to the p-block in the periodic table

THE REPRESENTATIVE ELEMENTS Group 7 A – The Halogens • Are named for their ability to form compounds with all metals (react easily) • These compounds are called salts therefore also called “salt formers” • Elements in this family have 7 valence electrons • Gain 1 electron = -1 charged ion • Fluorine is a gas & the most reactive of all halogens • Chlorine is a gas at room temperature, and has disinfectant and antiseptic qualities • Belong to the p-block in the periodic table

THE REPRESENTATIVE ELEMENTS Group 8 A – The Noble Gases • Among the last naturally occurring elements to be discovered because they are colorless and unreactive • Elements in this family have 8 valence electrons – They have a full outer shell of electrons = maximum number of electrons (8 electrons) except for helium, which has two • Have no charge because they are stable • Called nobles gases because they react rarely with other elements because of their stable electron configuration • Belong to the p-block in the periodic table.

THE TRANSITION METALS Groups 1 B- 8 B (or more commonly referred to as Groups 312) • Are in groups 3 -12 of the periodic table • Mostly dense and hard • Good conductors of electricity and heat, have luster, are malleable • Their valence electrons are in more than one electron shell – Can lose 2 electrons = +2 – Can form ions with a +3 or higher • Transition metals belong to the d-block in the periodic table

THE INNER TRANSITION METALS -- The Lanthanide Series (Period 6 on the Periodic Table) • Elements originally found in infrequently found minerals = rare earth elements • Silvery metals with relatively high melting points • All except for promethium are nonradioactive • Compounds of lanthanides are used in movie projectors, lasers, tinted sunglasses, welder’s goggles • Belong to the f-block in the periodic table

THE INNER TRANSITION METALS -The Actinide Series (Period 7 on the Periodic Table) • All are radioactive elements • Only 3 exist in nature, Thorium, Protactinium, & Uranium • The rest are synthetic elements called transuranium elements • A transuranium element is an elements whose atomic number is greater than 92 • Transuranium elements are created in particle accelerators or nuclear reactors • Plutonium used as fuel in nuclear power plants • Americium is used for home smoke detectors • Belong to the f-block in the periodic table

NEWLY DISCOVERED ELEMENTS -- Atomic Numbers 114, 116, & 118 • Some of the names of these elements are not officially assigned • Element with atomic # 114 was known as ununquadium (Uuq) • Is now know as Flerovium (Fl) • First produced by scientists in 1998 and IUPAC announced its official name until 2011 • Element with atomic # 116 currently went by Ununhexium(Uuh) • Is now known as Livermorium (Lv) • First produced in 2000 and IUPAC finally recommended the new name • Element with atomic # 118 goes by Ununoctium (Uuo) • Scientists believed they had made element 118 in 2002 • In 2011 IUPAC did not accept there was enough evidence to accept Uuo as an established element