PERIODIC TABLE

 

 

The purpose and history of the periodic table.

In science, there must be a start to develop all the periodic table key ideas and rules. Periodic table is an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same groups. The purpose of periodic table is to easily see the patterns and range of each atom and elements. Initially,  Mendeleev arranged the periodic table in order according to the increasing atomic mass from left to right. Later on, Moseley ordered the elements by properties rather than atomic mass. He also created an periodic law: the physical and chemical properties of the elements are periodic function of their atomic numbers.

 

The arrangement of the periodic table.

Periodic table has a lot of arrangements such as periods, groups, metals, metalloids, and nonmetals. The vertical columns are called group. There are alkali metals, alkaline-earth metals, transition metals, main group elements, halogens and noble gases. Other than that, there are 3 special groups, which are the noble gases, the Lanthanides, and the Actinides. Nobles gases are the most unreactive because the electrons in the outer shell are full. Lanthanides are the 14 similar in chemical & physical  elements with atomic numbers from 58 to 71. Actinides are the 14 elements with atomic numbers from 90 to 103.

 

 Trends about which you have learned using the periodic table 

The periodic table made it easy to show the trends of the atom from increasing size to attractiveness. Electronegativity increases as you move across the periodic table from left to right. Because the atomic mass increases and the attractiveness increases as well. But from up to down, the electronegativity decreases because the electrons are further away from the nucleus causing the attractiveness to decrease, but size will get bigger. Another trend is atomic radii, when you go across the periodic table , it decreases because  protons are being added to the nucleus, making it more positively charged. However, at the same time, the atom is getting smaller because the electrons are closer to the nucleus causing it to attract and pull in closer and tighter. But it will be difficult to remove one electron from the outer shell. From up to down, the atomic radii will increases as the amount of  electrons increases.