How are the elements arranged in the periodic table?

The periodic table is one of the greatest creations of modern chemistry. Its goal is to organize and give meaning to all the elements we find in the universe.

Usually a common question when we talk about the periodic table is: How were the elements classified before the periodic table was developed? The point is, the chemical elements have interested scientists for many centuries, but not until then Early nineteenth century So that the study and classification of the elements would be a major advance.

Periodic table wallpaper

The first chemist who came to the conclusion that it was necessary to group and classify the various elements was the German Johann Wolfgang Döbereiner (1780-1849): conceived of the idea of ​​arranging them into triads, groups of three elements having similar and comparable properties. Later, in the middle of the 19th century, the French geologist and mineralogist Alexandre-Emile Bigurre de Chancourtois He first classified the elements according to their atomic mass. For this he used some very complicated terms, which made his idea not very successful. Moreover, we cannot forget about it John Alexander Quinn Newlands, English analytical chemist, he was the first to publish the periodic table of the elements. He used to support his hypothesis by the Law of Eighty. A chemical law states: the chemical properties of the elements are repeated every 8 times. However, it was neither German nor French nor English who compiled the contemporary periodic table. I had to wait for the arrival Theories of the Russian alchemist.

Johann Wolfgang Döbereiner, the first scientist to propose a classification of the elements

Dmitri Ivanovich Mendeleev: Father of the Periodic Table

Mendeleev is considered the father of the periodic table He presented his idea of ​​classifying elements in 1869; Something inspired by the already existing background that I mentioned above. Mendeleev’s theory Select the following points:

• Item properties Cyclic If they are arranged by their atomic mass.
• Items that have properties similar, They also have similar atomic masses.
• Arrangement of items linked to their equivalence (The number of electrons lost for an element to reach its maximum energy level).
• Common elements, as a rule, small atomic mass.
• atomic mass very important, Because the nature of the element depends on it.
• More items They will be added to the table over time.
• It can happen that the atomic mass component varies.
• Item properties derived from its atomic mass.

Mendeleev’s periodic table contain 63 items, Items were added until the current number of 118 was reached.

Mendeleev, the father of the modern periodic table

Current periodic table variation

The current periodic table has been reconfigured and is based on standards somewhat different from that of Mendeleev’s table. For example:

• Elements of the current periodic table are no longer classified by their atomic mass, But they are now classified by increasing atomic number.
• In the same column we put the items that They have the same number of electrons in their outer shell. A criterion that does not entirely deviate from Mendeleev’s classification.
• The current periodic table contains 7 rows are called periods and 18 columns are called families.

View the current periodic table

the Latest updates that were implemented in the current periodic table dated from 2016, when International Union of Pure and Applied Chemistry (IUPAC)which represents the recognized authority for determination Rules and labels One of the items is the designation of some new features of the periodic table.

from 2016 review, Periodic Table 118 pcs Of which 83 are what we call “primitive” Also, the last 24 elements of the table are named elements “synthetics”, Because they did not exist on our planet and they were man made. Some of the elements can be found in supernova explosions.

In this example we can see the classification into groups and families of elements

Periodic table element families

In the current classification of the periodic table, all elements in the same family have same number of electrons in its outer shell, Which makes them chemical elements with similar properties. so by saying, react with the same type of compound Moreover, they form similar molecules and ions. There are many families, let’s see some of the main ones.

family of alkali metals

Lithium, sodium, potassium, rubidium, cesium, and francium are included in this family. All of these elements have outer shell with one electron, All of them form cations by losing an electron. These are shiny, smooth, and highly reactive metals. This is precisely because of him high reactivity, These minerals must be preserved in mineral oils so that they are not found as they are in nature. Of all, Sodium is the most common alkali metal in nature.

family of alkaline earth metals

This family includes metals such as beryllium, magnesium, calcium, strontium, barium, and radium. All of these elements have 2 electrons in its outer shell In addition, they all form cations by losing two electrons. Alkaline earth metals have a Silver luster Distinctive, and its name comes from the word earth, referring to the special characteristic of these minerals They can resist fire.

An example of a piece of magnesium

Lanthanide family

It consists of 15 elements, its name “lanthanide” It comes from the first of the elements in this family: the lanthanides. It comes to shiny metals, Able to quickly fogging the air It reacts quickly on contact with water. A group of elements containing some of the most closely related elements, such as lanthanum, cerium, gadolinium or terbium.

Actinide family

A family of elements consisting of 15 elements, which are heavy metals that take their name from the parent substance of the family: actinium. Actinides are all too radioactive Plus it’s soft and has silvery reflections. In this sense, we can cite uranium, plutonium, or thorium.

family of transition metals

The family of transition metals is a family that includes many elements own electronic configuration. This is because they are items that have a huge variety of colors, plus they look pretty cool electrical connectors. This family includes metals such as rhodium, palladium and copper Platinum and titanium.

Copper is one of the most widely used transition metals in the world.

Poor metal family

Poor metal family has Soft or brittle metals which tend to form covalent bonds. Some examples that we find in this family are aluminum, zinc, tin, mercury or lead.

Metalloid family

The metalloid family is a family of elements that have properties very precise. It looks like metal, however They are actually fragile and unable to conduct electricity. Among these metals we find boron and silicon arsenic or antimony.

The family of nonmetals

The family of nonmetals is a group of co-occurring elements Excellent thermal and electrical insulators. Nonmetals are elements that are absolutely necessary for planets Where there could be life like the earth. Among them we find carbon, nitrogen, oxygen, sulfur, or chlorine.

Sulfur is widely used in the manufacture of sulfuric acid: explosives, soaps, detergents, paints or plastics.

halogen family

The family of the penultimate elements is a family halogens, Which include elements such as fluorine, chlorine, bromine, iodine, and astatine. for all of these items They lack one electron to complete their last shell.

The noble gas family

The last family corresponds to the noble gas family. These gases too They are known as monatomic noble gases. Some of the most important gases in the universe include: helium Neon, argon, krypton, xenon and radon. They all have a complete outer shell that makes them little reaction, Because it is unable to form ions, nor participate in any molecule.