The Periodic Table of Elements

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 1800’s --- with discovery of electricity, the development of the spectrometer, the industrial revolution, compounds were broken down into their component elements & their identification became more accessible.

Historical Development of the Periodic Table -- continued 1864 ---John Newlands, am 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. In other words, the first and the eight elements had similar properties.

Historical Development of the Periodic Table -- continued 1869 --- Lothen Meyer (a German chemist) & Dmitri Mendeleev ( a Russian chemist) organized elements by increasing atomic mass into columns with similar properties, which 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” The groups designated with a letter “A” (1A to 8A) are often referred as the main group or the “REPRESENTATIVE ELEMENTS” The groups designated with a “B” (1B through 8B) are referred to as the “TRANSITION ELEMENTS” A more recent numbering system, which uses the numbers 1 through 18, also appears above each group

The Modern Periodic Table --- continued Period ( rows on the periodic table) Consists of rows called Periods (There are 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 --- elements that are 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. Silicon and Germanium are two of the most important metalloids, as they are used extensively in computer chips and solar cells. Metalloids are in purple

THE REPRESENTATIVE ELEMENTS Group 1A – The Alkali Metals Elements in this family have 1 valance electron. Lose their valance electron to form a +1 charged ion. Good conductors of heat and electricity. Found combined with other elements in nature due to their high reactivity. Soft enough to cut with a knife. Stored in oil to prevent a reaction with oxygen in the air. Belong to the s-block in the periodic table.

THE REPRESENTATIVE ELEMENTS Group 2A – The Alkaline Earth Metals Elements in this family have 2 valance electrons. Lose their valance electrons to form a +2 charged ion. Form compounds with oxygen called oxides. 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 3A – The Boron Group Is named for the metalloid Boron Elements in this family have 3 valance electrons Lose their valance electrons to form a +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 4A – The Carbon Group Is named for the nonmetal Carbon Elements in this family have 4 valance electrons Lose their valance electrons to form a +4 charged ion OR can gain 4 electrons and form a –4 charged ion. Contains one of the most important elements on the periodic table, which is carbon. Contains all three classifications: carbon is a nonmetal, silicon and germanium are metalloids, and tin and lead are metals Belong to the p-block in the periodic table.

THE REPRESENTATIVE ELEMENTS Group 5A – The Nitrogen Group Is named for the nonmetal Nitrogen Elements in this family have 5 valance electrons Gain 3 electrons to form a -3 charged ion. Except Bismuth About 78% of Earth’s atmosphere is nitrogen; proteins and other essential organic compounds contain nitrogen. Contains all three classifications: nitrogen & phosphorus are nonmetals, arsenic & antimony are metalloids, and bismuth is a metal. Belong to the p-block in the periodic table.

THE REPRESENTATIVE ELEMENTS Group 6A – The Oxygen Group Is named for the nonmetal Oxygen. Elements in this family have 6 valance electrons. Gain 2 electrons to form a -2 charged ion. Polonium is the most metallic member of this family; it was discovered by Marie & Pierre Curie and named after there native land Poland; it is rare, radioactive & extremely toxic. Contains all three classifications: oxygen and sulfur are nonmetals, selenium & tellurium are metalloids, and polonium is a metal. Belong to the p-block in the periodic table.

THE REPRESENTATIVE ELEMENTS Group 7A – The Halogens Are named for their ability to form compounds with all metals. Because these compounds are called salts, Group 7A are called “salt formers,” or Halogens Elements in this family have 7 valance electrons. Gain 1 electron to form a -1 charged ion. Fluorine is a gas & the most reactive of all halogens. Chlorine is a gas at room temperature. Bromine is a liquid, but evaporates easily. Iodine is a solid that an change directly into a vapor. Astatine is radioactive with no known uses. Belong to the p-block in the periodic table.

THE REPRESENTATIVE ELEMENTS Group 8A – The Noble Gases Were among the last naturally occurring elements to be discovered because they are colorless and unreactive. Elements in this family have 8 valance electrons. This means they have the maximum number of electrons in their outermost energy level, 8, except for helium, which has two. Oxidation Number: These elements do not have a charge as they have a full octet. Nobles gases react rarely because of their stable electron configuration. There are no known compounds of helium, neon, & argon. In 1962, inorganic chemist, Neil Bartlett created a compound of xenon and Fluorine. Belong to the p-block in the periodic table.

THE TRANSITION METALS Groups 1B- 8B (or more commonly referred to as Groups 3-12) Conduct electricity & heat; have luster, are malleable Most are hard solids with high melting & boiling points. Transition metals can lose 2 s electrons and form an ion with a +2 charge Because unpaired electrons can move to the outer energy level, these elements can form ions with a +3 charge or higher, as well. Silver, gold, platinum & palladium are the only transition metals that are unreactive enough to be found in nature uncombined Transition metals belong to the d-block in the periodic table Metals such as iron, cobalt & nickel are said to be ferromagnetic (which means they are strongly attracted to a magnetic field.)

THE INNER TRANSITION METALS -- The Lanthanide Series (Period 6 on the Periodic Table) Silvery metals with relatively high melting points. Because there is very little variation in properties among the inner transition metals, they are found mixed together in nature and are extremely difficult to separate. Compounds of lanthanides are used in movie projectors, lasers, high-intensity search lights, tinted sunglasses, welder’s goggles, & in the steel industry to remove carbon from iron. Oxides of some of these metals are used in television screens and computer monitors

THE INNER TRANSITION METALS -- The Actinide Series (Period 7 on the Periodic Table) Actinides are radioactive elements. Only 3 actinides 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 creates in particle accelerators or nuclear reactors. Most transuranium elements decay quickly, except for plutonium-239, which can remain radioactive for thousands of years. Plutonium is used as fuel in nuclear power plants. Americium is used for home smoke detectors.

NEWLY DISCOVERED ELEMENTS -- Atomic Numbers 114, 116, & 118 The names of these elements are not officially assigned. Element with atomic # 114 currently goes by Ununquadium and has a mass of 285 atomic mass units. Element with atomic # 116 currently goes by Ununhexium and has a mass of 289 atomic mass units. Element with atomic # 118 currently goes by Ununodium and has a mass of 293 atomic mass units.