The chemical elements are shown in a table in the Periodic Table of the Elements (PSE for short) and should not be missing in any table work. Why is this element table used in chemistry? And how does the periodic table of the elements work? We provide you with the periodic table explanation in our guide , so that you keep an overview of main periodic table groups and atomic numbers and reveal where you can get a periodic table to print out.
The chemistry periodic table appears confusing at first glance, but the information in the element table has a logical explanation and is less complex once you have understood the PSE. But who invented the periodic table of the elements? As early as 1869, the Russian Dmitri Mendeleev and the German Lothar Meyer came up with a similar idea to represent the chemical elements. The Mendeleev table of elements has prevailed to this day.
Periodic table: explanation of the elements
The well-known PSE refers to the atoms in their electrically neutral state, which means that the same number of negative electrons (-) are present in the electron shell as protons (+) in the atomic nucleus.
The elements are arranged according to their atomic number. This indicates how many positively charged particles (protons) are present in the atomic nucleus. The first element with the atomic number 1 is hydrogen. Up to 118 protons in the nucleus of the element Ununoctium are currently known.
Mass and atomic radius increase from top left to bottom and right (with some exceptions).
The element table is divided into period groups: main and sub-groups (vertical), a total of 18 groups.
It consists of 7 lines (horizontal), which are also called periods.
The 18 columns identify the different main and sub-groups. Elements in a group have similar chemical properties and the same number of outer electrons in the atomic shell (also called valence electrons). The properties are more similar for elements within a main group than for elements within a subgroup.
There are 8 main groups, in columns 1-2 and 13-18.
The sub-groups can be found in spades 3-12 and are only 4 lines high. The chemical elements in it are also called transition metals. There is another table for these, in which the actinoids and lanthanoids are listed./li>
Oxygen in the periodic table of the elements
Oxygen has an atomic number of 8 and has 8 protons in the nucleus and 8 electrons in the outer shell.
If you want a practical PDF, you can print it out on the following pages:
PSE explains: This is what the information about the element means (example oxygen)
The elements are identified by a symbol (letter). So H stands for hydrogen for the first element, He for helium.
As a rule, the atomic number is at the top left and indicates the nuclear charge, i.e. how many protons the atomic nucleus contains.
Depending on the form of representation, you can also read the physical state, i.e. whether the element is solid, liquid or gaseous. Sometimes the background is highlighted or the atomic number is colored and provides information about the physical state.
Optionally, for example, there is something at the top right of the occurrence of the element: is it natural, artificial or radioactive. But be careful: an element can also be artificial and radioactive. Here you should pay attention to the respective legend under the table. All elements are stable up to lead (element 82), so there are no radioactive isotopes. Technetium (43) and 61 (Promethium) are exceptions. The PSE therefore shows 80 stable elements that occur naturally.
Main groups explained
The elements are sorted by atomic numbers (top left) and the main groups can be found in the first two vertical columns and in columns 13-18.
alkaline earth metals
Boron group / earth metals
Chalkogene / oxygen group
Halogens / fluoro group
Noble gases / helium group
To get back to the outer electrons: For example, group 1 (I) contains hydrogen and alkali metals. The number of valence electrons is 1. This means that elements in this group each have an outer electron. Alkaline earth metals have 2, the elements on the boron group have 3 valence electrons.
Colored division into groups
Depending on the form of presentation, a colored bar at the bottom or a background in a specific color shows which element series it is: Is it a non-metal, alkali metal, alkaline earth metal or another type? Below we have listed the series and examples for you: