Periodic Table

Length: 3 Pages 864 Words

Intro: What is the periodic table? The periodic table is a rectangle that every one to day recognizes. This function of grouping the chemical elements was created by several European scientists; it all started in the 1860’s. In 1863, a French geologist, A. E. Béguyer de Chancourtois created a list of the elements in the periodic table and arranged the elements by increasing atomic weight. The list was wrapped around a cylinder so that sets of similar elements lined up, creating the first representation of the periodic table. In England, a chemist by the name of John A. R. Newlands was also wrapping the elements, noticing that the chemical groups repeated after every eight elements. He named this the octave rule, and compared it to a musical scale. His work was considered to be absurd, so his work was ignored for years. Chemists Dmitrii I. Mendeleev, a Russian, and German Lothar Meyer were working independently to arrange the elements into seven columns, corresponding to various chemical and physical properties. Then latter came the periodic table as of to day to be what we see. Some of the parts of the modern periodic table are groups/families, and periods. There are many groups/families in the periodic table. The Continue...

The Atomic size of the element decreases from left to right across a period, but atomic mass increases from left to right across a period. All the noble gasses are found in small amounts in the earth's atmosphere. The family of noble gasses is helium, neon, argon, krypton, xenon, and radon. The right hand diagram shows what happens if the atoms are just touching. Ionization energy can be defined as being the energy required to remove the outermost electron from a gaseous atom. The horizontal rows of the periodic table are called periods. Noble Gasses are colorless gasses that are extremely unreactive, because do not combine with other elements to form compounds, the noble gasses are called inert. The left hand diagram shows bonded atoms. Like the alkali metals, the alkaline metals are never found free in nature they are also made by chemical means. Alkaline Earth Metals are beryllium, magnesium, calcium, strontium, barium, and radium. The chemical reactivity of the halogens is due to the number of electrons in the outermost energy levels of their atoms, Fluorine is the most active halogen. Many transition metals are combined chemically with oxygen to form compounds called oxides. A "gaseous atom" means an atom that is all by itself, not hooked up to others in a solid or a liquid. The Alkali Metals are the elements in Group IA of the periodic table.