Which element has no elementary particles

Atoms as building blocks of the universe

Lots of gold atoms: gold coin
1 gold atom
Atoms are the building blocks for the variety of chemical compounds, salts, molecules and for the entire world of substances. Pure gold, for example, is only made up of gold atoms. Since nobody has seen gold atoms before, symbols are introduced for the atoms. The atoms themselves are made up of their components, the elementary particles, and these in turn are made up of the quarks. In addition to the three elementary particles protons, neutrons and electrons, others are known, but they do not play an essential role in the structure of an atom in terms of mass. The protons and neutrons in the atomic nucleus are called Nukleons designated. The sum of all nucleons in an atom gives the Nucleon number.

Abbreviation (charge)
Rest mass
Atomic nucleus
1,6724 × 10−24 G
n (none)
Atomic nucleus
1,6748 × 10−24 G
eAtomic shell
9,109 × 10−28 G
Every system level - the substance, the atom and the elementary particle - can be viewed as an independent system. This principle can also be continued in the visible world up to the universe. The elementary particles make up the atoms, the atoms make up the molecules, the molecules make up the cells, etc .:


An atom has very few properties that can be described using terms from the world of experience. It is countable, has mass, spatial symmetry (but not volume!), Energy and composition. The properties of a substance cannot be reduced to its components: Gold atoms have no color. Only a certain type of interaction between components and forces in the system creates the gloss and the golden yellow color impression.

In the periodic table, the elementary atoms are arranged in ascending order according to the number of protons in their atoms.

1 hydrogen atom has 1 proton (hydrogen: atomic number 1)
1 helium atom has 2 protons (helium: atomic number 2)
1 lithium atom has 3 protons (lithium: atomic number 3)

The positive charge of the protons in the atomic nucleus is balanced by the negative charge of the electrons. The element no.1, hydrogen always has 1 proton and 1 electron, the following applies:

Ordinal number = proton number = atomic number = electron number = element number in the PSE

A carbon atom has 6 protons and 6 neutrons in the atomic nucleus and 6 electrons in the atomic shell. The number of nucleons is 12. The number of nucleons is often written over the number of protons to the left of the individual element symbol. This notation is by no means recommended for the periodic table, because otherwise the number of nucleons can be confused with the relative atomic mass.

The number on the top left, the Mass number or Nucleon number indicates how many nucleons are contained in an atom.
The number at the bottom left also indicates the Atomic number, the Atomic number, the Proton number and the Electron count at.

When writing the isotopes, the number at the bottom left is often left out. You can also just write C-12 with a hyphen. Since the electrons have a negligible mass compared to the core particles, they play practically no role in the total mass. The following applies:
Neutron number = mass number - proton number

The elementary atoms in the periodic table are arranged with increasing atomic number from left to right in several periods. Since the atomic number corresponds to the number of protons and the number of electrons, one can also say that the elementary atoms are arranged with an increasing number of protons or electrons.

The development of the atomic concept

The theories about the individual atomic ideas are detailed in the portraits of the respective researchers or in the linked terms.

Time, nametheory
around 400 BC,

"Atomos" is seen by Democritus as a universal, philosophical principle, man as "A cosmos on a small scale".

Antoine Lavoisier
The "Substances simple" sees Lavoisier as "Éléments" (Element) or "Principes" (Urranfang), they do not appear visibly, but act as principles in the structure of the body.
John Dalton
Each element consists of atoms of the same type, den "Last particle"that are in a relative weight to each other.
J. J. Berzelius
More precise determination of the atomic mass ("Atomic weight table") compared to Dalton.
1832, Michael FaradayElectrolysis experiments, introduction of the concept of ions.
Stanislao Cannizaro
Clarification of the term molecule (reference to Avogadro) and differentiation between atom and molecule: "The different amounts of the same element contained in the different molecules are all whole multiples of the same amount, which, since it always occurs as a whole, must be called an atom."
Svante Arrhenius
Dissociation in salt solutions: When table salt is dissolved in water, ions, i.e. charged atoms, are formed.
Henri Becquerel
Discovery of radioactivity: Uranium ore (and uranium) emit radiation that blackens photographic plates.
around 1900, Wilhelm Ostwald, L. BoltzmannOstwald: There are no atoms, matter is a pure phenomenon of energy; Dispute with Ludwig Boltzmann and Max Planck, the representatives of one "Atomic Theory".
1908, Joseph John ThomsonThomson's atomic model: The atom is filled with a positively charged cloud in which the electrons are distributed like raisins.
Ernest Rutherford
Rutherford's atomic model. The atom resembles a planetary system in which the negatively charged electrons orbit a positively charged nucleus, the protons.
Niels Bohr
Bohr's model of the atom: The electrons travel on certain paths at fixed intervals around the atomic nucleus. When emitting or absorbing radiation, the electrons of the hydrogen atom jump between these “shells”.
1913, Frederick SoddyTheory of isotopes
Arnold Sommerfeld
Refinement of the Bohr model, elucidation of the fine structure of the spectral lines.
1916, G.N. LewisCovalent bond ("atomic bond", electron pair bond).
1920s, quantum physics around Schrödinger,
Task of the clear presentation of circling electrons, instead a mathematical scheme (matrix mechanics, wave mechanics). With Schrödinger “matter waves” instead of circling electrons. Heisenberg's uncertainty principle: two measurements of an electron such as position and momentum cannot be determined at the same time.
Complementarity principle: light shows particles and Wave structure, it depends on the way you look at it.
Orbital model (shell model): Two electrons of an atom are always in a so-called orbital. This means the probable location of the two electrons.
James Chadwick
Discovery and proof of the neutron, whose existence was predicted by Rutherford as early as 1920.
Linus Pauling
Appearance of resonance in bonding electrons, hybrid orbital model, electronegativity, hydrogen bridge bonding.
1961, Murray Gell-Mann and Kazuhiko NishijiamaDiscovery of the quarks.

Create a book individually: basic text atomic term


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