Development of Periodic Table

Periodic Table

Development of Periodic table: Antoine Lavoisier  In the late 1790's compiled a list of 23 known elements

Johann Dobereiner (1780-1849) German Chemist  In 1817, he realized that 3 metal elements: Strontium, Calcium, and Barium, were very similar (called this group a triad.)

John (J.A.R.)Newlands (1837-1898) English Chemist  In 1864, he noticed that when the elements were arranged by increasing atomic mass, their properties repeated every 8th element. He then arranged the 49 elements into 7 groups of 7 each. Lead to the Law of Octet: States that an atom with 8 electrons in its outer level is nonreactive and the most electrons on it outermost energy level (shell) is eight.

Dmitri Mendeleev (1834-1907) Russian chemist  In 1869 that put together the 1st periodic table-Table not completely correct German Chemist Lothar Meyer (1830-1895) helped him but Mendeleev received most of the credit

Henry Moseley (1887-1915) English chemist  He discovered that the atomic number was equal to the amount of protons in the nucleus and lead to the true arrangement of the Periodic table.  Resulted in a clear periodic pattern of properties. The Periodic Law states that the chemical and physical properties of the elements are a periodic function of their atomic numbers.

A period in the periodic table is all the elements in a horizontal row.

A group in the periodic table is all the elements located in the same vertical column, which is assigned a number from 1-18.  When elements in a group have similar characteristics they are sometimes called a family.

METALS  Usually shiny when smooth and clean Conduct heat and electricity well Solid at room temperature Most are also ductile and malleable (meaning they can be pounded into thin sheets and drawn into wire.) Chemically reactive Positively charged These atoms have only a few electrons in the outer level. Have a tendency to lose their electrons in the outermost level. . Alkali metals: Group 1A except H They react with water

1 Easily lose a valence electron and form an ion with a +1 charge. Ends in sublevel s1 . Alkaline Earth metals: Group 2A Reactivity similar to Alkali metals but not as great 2+ charge Strontium gives some fireworks a crimson color Ends in sublevel s2 . Aluminum Group (Sometimes called the Boron Group) Group 13 (IIIA) Aluminum the most plentiful metal in the Earth's crust.  Transition Elements for divided into 2 set: 1. Transition metals . Any element in columns 3-12 (IIIB-IIB) . Has 2 electrons in the outer level - 4s2 . Elements with #'s 22-28 also have a 3d sublevel . In all groups except 12 (IIB), the d orbitals are only partially filled. . Share properties such as electrical conductivity, luster, and malleability with other metals. . Major different is in strength. . They have magnetism . They play an important role in the economy of many countries because of their wide variety of uses. Used in plastics, wire, zinc is a protective coating, some form alloys to make such things as jet engines, drill bits, and surgical instruments. Cobalt in needed for the development of red blood cells. Manganese and copper are involved in cell respiration. Molecules that help digest proteins and eliminate CO2 contain zinc. 2. Inner transition metals: Lanthanoid Series and Actinoid Series . Group B . To make the periodic table more manageable, these 2 series have been removed and located below. . They are the highest energy electrons (f electrons) are inside the d sublevel and the outer level. . Both have outer shells consisting of an s2 sublevel  Lanthanoid Series- Lanthanum (57) to Ytterbium (70) Electrons are added to the 4f sublevel instead of the sixth or outer level Are silvery metals with relatively high melting points Used extensively as phosphors, substances that emits light when struck by electrons.  Actinoid Series-Actinium (89) to Nobelium (102) This series have an increasing # of electrons in the 5f sublevel They are all radioactive.

NONMETALS . These are usually gases or brittle solids at room temperature. . Dull appearance . Insulators . Outer electrons are held closely by the nucleus . Form negative ions (anions) . Have 5 or more electrons in the outer level than metals. . They often gain electrons or share their electrons in the outermost level.  Group 4A also known as Group 14: Carbon Group 2 o Allotropes are found in this group: forms of an element in the same physical state that have different structures and properties. Ex. Carbon in the form of coal, Diamonds and graphite o Silicates are silicon compounds bound to Oxygen, and each Si atom is surrounded by 4 O atoms.  Group 5A also known as Group 15: The Nitrogen and Phosphorus Group o There are nonmetals (N and P), metalloids (As and Sb), and metals (Bi) o Each has 5 valence electrons and have many different properties o Charge is -3  Group 6A also known as Group 16: The Oxygen Group or Chalogens

o Have 2 allotropes: Ozone, and O2

o Some are oxides known as amphoteric: Those that can produce either acidic or basic

solutions. Ex. Sulfur compounds like sulfuric acid (H2SO4)

o Charge is a -2  The highly reactive Group 7A also called Group 17 elements are called Halogens. o Fluorine is the most reactive element- Highly electronegativity o Astatine the only radioactive element (At) o Halogens make salts o Have 7 valence electrons and often tend to share one electron or gain one. o Have a 1- charge so they react with Group 1 the most  The extremely nonreactive Group 8A also called Group 18 and is known as Noble gases. o All except Helium have 8 electrons in their outer level. o In 1962, the inorganic chemist Neil Barlett chemically bonded Fluorine and Xenon. . The first compound made with a noble gas was xenon hexafluorplatinate (XePt F6)

METALLOIDS  These are elements with physical and chemical properties of both metals and nonmetals.  Silicon and germanium are used a lot in making computer chips and solar cells.  Staircase elements between metals and nonmetals  Are often brittle solids

Special Elements Carbon  found in every cell in your body  Has four places where it can bond  Charge is +4

Nitrogen  78% of atmospheric gases  Used to make proteins in your body  Has three places where it can bond  Charge is -3