| Course ID | Course | Professor | Time | Location |
| Periodic table of elements | - |
Periodic table of elements
Elements are classified in Atomic number, see periodic table above.
The periodic table dates back to the work of Lothar Meyer and Dimitri Mendelejev in 1869.
Elements are in ascending order of atomic mass . Here similarities emerge periodically in their properties. Groups of Elements with similar properties are listed in vertical columnns.
Column 1,2 and 3 to 8 are main groups. 10 Columns between maingroup 2 and 3 are subgroups or secondary groups.
The first and the 7th group of the periodic table are the elements H, Li, Na, K, etc. and F, Cl, Br, I, halogenids, these elements may only enter into one binding. E.g. NaCl, H2O2 (Hydrogenperoxide) H is only bond with one O. NaCl2 is inexistent! HBr, CCl4. The 8th group are noble gases. They do not undergo any chmemical reactions!
The horizonal rows are called periodes.
The first periode consists just of hydrogen, H and helium, He. Atomic number 1 to 2.
The third and fourth periode consists of atomic numbers 19 to 36 and 37 to 54, 18 elements each.
After that there folow two periodes with 31 elements, 55 to 86 an 87 to 118.
Lanthanides or rare earth have the atomic number 58 to 71.They are found below the periodic table as footnote, aswell the actinides no 90 to 103.
Elements with atomic numbers 110 to 118 are not mentioned on this table of elements. Some of them have been produced artifically.
Most of the elements are metals. First groups except hydrogen are called alkali metals.
In the second group are the alkaline earth metals. They enter into two bindings. Example CaCl2
All the elements of the subgroups are metals or also called transition metals.
Aswell the atomic numbers, 13, 31, 32, 49 to 51 and 81 to 84 are defined as metals. Elements Nr. 5, 14, 32 bis 34, 51, 52 und 85 are called semimetals.
All the metals have the properties of metallic luster, ductility and electrical conductivity.
Second Periode, the groups 3 to 6 the element B enters into 3, C into 4, N into 3 and O into 2 bindings. C, N, and O are the most important elements used in organic chemistry.
In higher lesson of basic level you will learn more about electromagnetic radiation, atomic spectra, wave mechanics, quantum numbers, orbital occupation and electron configuration.