Jons Jacob Berzelius: system of signs
The vast majority of elements, on the other hand, are mixed elements. All atoms of a mixed element have the same number of protons in the atomic nucleus according to the element definition, but the number of neutrons in the nucleus is different - statistics homework help . Such particles (nuclides) are called isotopes (Greek: iso topos = same place). All isotopes of an element occupy the same place in the periodic table of the elements and are characterised with the same element symbol. The element chlorine has two isotopes, chlorine-35 and chlorine-37, each with 17 protons in the nucleus. Out of 1 000 chlorine atoms, 755 atoms have 18 neutrons in the nucleus (isotope chlorine-35) and 245 atoms have 20 neutrons in the nucleus (isotope chlorine-37). Natural tin, for example, is a mixture of 10 different isotopes. All of them contain 50 protons in the nucleus, but they differ in the number of neutrons (62, 64, 65, 66, 67, 68, 69, 70, 72, 74).
The chemist Jons Jacob Berzelius (1797-1848) proposed a system of signs that is still used all over the world - do my math homework for me . He formed the signs for an element from the letters of the Greek or Latin name of that element and called these signs symbols.
Meaning of a symbol:
1. the symbol is a sign for the substance.
2. it is the chemical sign for an element.
3. it is the sign for an atom of the element.
Today, more than 100 elements are known.
Therefore, it is very important to have a tool that brings order to the variety of elements and their atoms - do my assignment . This aid is the Periodic Table of the Elements (PSE) developed independently by Lothar Meyer (1830-1895) and Dmitry Mendeleev (1834-1907).
The number of protons in the nucleus is the atomic number, it determines the position of the element in the periodic table. Thus, the field for the element chlorine (17 protons in the nucleus) is marked 17Cl in the PSE.