How to arrange the elements in the modern periodic table?

 

Russian chemist "Dmitry Mendeleev" published his first attempt to group chemical elements and tabulate them according to their atomic weights in the late nineteenth century. There were only 60 known chemical elements in that period, but Mendeleev had noticed the alignment of some elements in a regular order in the form of regular and successive cycles, when he organized the known elements at their time according to their atomic weights.

What is the periodic table and why is it important?

Today, 150 years later, chemists are already dealing with 118 known chemical elements (after adding four new elements in 2016) and the order of elements that Mendeleev used in his chemical table is still followed, as the modern periodic table begins with the simplest atom: the hydrogen atom, then Then the rest of the elements are lined up according to their atomic numbers (and the atomic number is the number of positive protons in an atom). With few exceptions, the arrangement of the elements is completely compatible with the increasing mass of the atoms of the successive chemical elements.

The modern periodic table contains 7 rows (periods) and 18 columns, each of the seven rows representing a cycle. The number of each cycle indicates the number of electrons present in its energy levels.

If we take the element sodium as an example, we will see that it is in the third cycle, which means that the sodium atom contains electrons with only the first three energy levels.

And if you go down a little further, the revolutions will be longer, as they hold more electrons occupying more energy levels that are higher and more complex.

 

As for the columns in the table, they represent groups of elements ... or families, so to speak, as the elements in one group behave and interact similarly, as they contain the same number of electrons in the final envelope of the elements, that last level and the face that they show to the world.

The group 18 elements, for example, all contain a final level that is completely filled and saturated with electrons, and therefore they rarely participate in chemical reactions, as they do not need to lose an electron or gain another.

Chemical elements in the periodic table are usually classified as either metallic or non-metallic elements, but the line between them is very vague and complex. Metals are usually good conductors of heat and electricity, but subgroups between metals also have identical properties and chemical properties similar to those groups.

So the modern periodic table description of the elements divides it into fairly acceptable symmetric groups, according to the Los Alamos National Laboratory.

Sections of the modern periodic table

Alkali metals

The alkali metals make up most of the first group, that is, they are aligned to occupy the first column of the table. It is shiny and smooth enough to be cut smoothly with a knife. The group of alkali metals begins with the element lithium, its chemical symbol “Li,” and ends with the element “Fr”.

They are also highly chemically active, flammable and explosive elements in contact with water, so chemists store them in inert gases or under oils. Hydrogen (an atom with a single electron) is also in Group A, but it is a gas and is not considered a metal.

Alkali earth metals

Naturally, the alkali earth metals form the second group of the periodic table, beginning with the element beryllium and its chemical symbol "Be", and ending with the element "radium".

Each element of this group contains two electrons in its last external energy level, which makes it highly reactive and chemically active in order not to exist alone in nature, but it is not with the same strength and activity that characterizes the group of alkali metals.

The reactions of the alkali earth metals are slower and their thermal reactions are lower compared to the alkali metals of the first group.

Lanthanides

It forms the third group of the modern periodic table, but it is too long to fit in one column, so it was cropped and placed horizontally to form the top row of that floating island at the bottom of the periodic table (which is formed from the lanthanides and actinides that we will discuss shortly).

 

The lanthanides are made up of elements 57 to 71. It begins with the element "La" and ends with the element "L". The elements of this group are distinguished by their silvery white color, and this color is deformed if exposed to air.

Actinides

Naturally actinides make up the bottom row of the island we talked about below the table. It contains elements starting from element 89, which is actinium “Ac”, and ending with element “L”, which is element number 103. Thorium and uranium “Ur” are present in this group, and they are present in the earth's crust in large quantities and both are radioactive.

This island of lanthanides and actinides together form a group called the endogenous transition metals.

Transition metals

Leaving that island below and returning to the main construction of the periodic table of elements, groups from column 3 to 12 together form the group of transition metals.

These metals are hard, but are also flexible, shiny and good conductors of electricity and heat. In fact, these elements are what you think of when you hear the word "metals", as they contain gold, silver, iron and platinum among their elements.

 

Metals after transition

Before we move on to the non-metallic or non-metallic side, the properties of the elements do not subdivide and differ directly on the columns of the groups nor do they share the properties exactly as well.

And it extends from group 13 to group 17 in the periodic table.

The group has some classic properties of the transition metals, but they tend to be softer and less conductive compared to the transition metals.

Many periodic tables show a dark streak, similar to a tilted amphitheater connecting boron to statin. In the lower left of this ladder lies the post-transition metallic group.

Metalloids

In the order, they are boron "B" - silicon "Si" - Germanic "Ge" - arsenic "As" - antimony "Sb" - tellurium "Te" - and polonium "Po".

It is what constitutes that gradation between metallic and non-metallic minerals. Some of these elements behave as semiconductors, such as boron, silicon, and germanium, rather than as conductors. They are also called semiconductors and semiconductors, sometimes called poor metals.

Nonmetals

All that is in the top right of that stepped staircase that we talked about, with the hydrogen that got its share of the first group, are non-metallic materials.

Among those elements: carbon "C" - nitrogen "N" - phosphorus "P" - oxygen "O" - sulfur "S" - and selenium "SE".

Halogens

They are the first four elements in Group 17, from fluorine "F" to the astatin "At", which is one of two subgroups of nonmetals.

The halogens interact chemically and tend to bind with the alkali metals that we talked about at the beginning to produce different types of salts, for example: table salt in our homes is nothing but a product of the reaction of sodium, which is an alkali, with chlorine, which is one of the halogens.

Inert (noble) gases

They are colorless, odorless, and almost completely chemically inert, so they do not participate in the reactions. Also called the noble gases, it is located in the 18th group at the extreme end of the periodic table.

Many chemists expect that one of the four newly discovered elements will exhibit the same properties as Oganesson. However, even today chemists have not been able to directly test it, since its half-life is measured in milliseconds. The “Oganesson” component completed the seventh session of the periodic table.

So if someone can discover or create the 119th element (and the race is currently underway in this regard) then the eighth cycle will start in the first column of the alkali metals.

Because of the periodic nature that gives the periodic table its name, some chemists prefer to visualize Mendeleev's table in the form of a circular table on the circumference of a cylinder, where its beginning meets its end.