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Modern periodic table and classification of Elements

From Online Sciences - December 6, 2017

The modern periodic table consists of 7 periods ( horizontal rows ) , 18 groups ( vertical columns ) , The elements are arranged ascendingly according to their atomic numbers and the way to fill their atomic energy sublevels by electrons according to the Aufbeau ( building-up ) principle , where each element has one electron more than the element preceds it .

Modern periodic table

The atomic number of each element increases than the element preceds it in the same period by whole one , Each period begins by filling a new energy level with one electron , then filling the atomic energy sublevels lying in the same period successively , until we reach the last element in the period which is a noble gas that has completely filled energy levels .

The elements of the same vertical group are identical in the electronic composition of the highest ( outermost ) energy level , different in the principal quantum number ( n ) .

Both of sodium 11Na and potassium 19K have similar properties , Because they are identical in the electronic composition of the highest ( outermost ) energy level ( ns ) .

Elements blocks of the modern periodic table

The table is divided into four main blocks , these blocks are s-block , p-block , d-block and f-block

s-block elements

They are placed in the left hand block of the table , The s-block contains the elements whose outermost electrons occupy the s sub-level , The s-block consists of two groups of elements , they are :

1A whose electronic configuration ends with ns , 2A whose electronic configuration ends with ns , where n is the number of the outer energy level and the number of period at the same time .

p-block elements

The occupy the right hand block of the table , Thep-block contains the elements whose outermost electrons occupy the p sublevel except helium ,The p-block consists of six groups , characterized by symbol A except zero group .

d-block elements

They occupy the middle block of the table , The d-block contains the elements with the outermost electrons occupy the d sublevel , The d-block consists of 10 vertical columns representing 8 groups which are characterized by the symbol B except eighth group which consists of 3 vertical columns .

The d-block elements are classified according to the number of the outer energy level and the period number into three series which are :

f-block elements

They are separated down the table , to avoid being a very wide table , In which the f sub-level is filled successively , The f-block is divided into serieseach of them includes 14 elementswhich are :

The number of elements of any series of the f-block is 14 elements , while d-block contains 10 elements , because f-block elements in which the f-sublevel is successively filled and it consists of 7 orbitals , while d-block elements in which the d-sublevel consists of 5 orbitals and each orbital is occupied by 2 electrons .

Types of the periodic table elements

It is possible to classify the elements in periodic table into four types which are :

Noble gases

They are the elements of the zero group 18 which is the last column of the p-block , They are characterized by having energy levels completely filled by electrons and their electronic structure is np6 , except that of helium 2He which is 1s .

Noble gases may form compounds , but with great difficulty , because they are very stable elements as their energy levels are completely filled by electrons .

The representative elements

They are the elements of s and p-blocks , except that of zero group , They occupy the groups from 1 A : 7 A , These elements are characterized by the complete filling of all the energy levels with electrons , except for the highest level .

They are active elements , because their highest level tends to reach the completed configuration similar to the nearest noble gas ( ns , np6 ) by gaining , losing or sharing electrons .

Ex : 11NaNa+ ( loses 1 electron )

1s , 2s , 2p6 , 3s1s , 2s , 2p6 ( similar to the electronic configuration of neon gas 10Ne )

The main transition elements

The inner transition elements

The elements configuration in the light of the modern periodic table
Determination of the element location in the periodic table

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