Long form or Modern form of periodic table | مصادر الكيمياء

Long form or Modern form of periodic table

 

 

Long form or Modern form of periodic table

The modem form of period table is based on increasing order of atomic number. General features of the table is as follows:

1 –  There are 18 vertical columns which arc called groups. They are numbered in the old form by IA, IB, IIA, IIB, … VIIA, VIIB VIII and 0 (zero) and in the new form from 1 to 18.

2 – Elements of groups 1, 2 and from 13-17  have only outermost shell incomplete. Each one of their inner shells arc complete. These are called normal elements. Group number 1 called alkaline elements and group number 2 called alkaline earth elements and number 17 halogens.

3 – Outermost shell as well as the penultimate shells in elements belonging to groups 4 to 12 are incomplete. These are termed transition elements.

4 – Groups belonging to inert gases is called zero group These elements have all their shells complete.

5 – There are seven horizontal rows also known as periods.

6 –  The first period has two elements (H and He).

7 –  Second and third period are short periods, each consisting of eight elements.

8 – Fourth and fifth are long periods each consisting of 18 electrons .

9 –  Six row is a long period. It consists of 32 elements, including 14 elements known as lanthanides.

10 –  Seventh period also a long period. It consists of 32 elements, including 14 elements known as actinides.

11 –  Elements with atomic numbers 57 to 71 (known as lanthanides) and with atomic number 89 to 103 (known as actinides) are placed in two separate rows at the bottom of the table. Elements present in each of these series have very similar properties.

12 –  The whole periodic table is divided into four blocks : s-block (groups 1 and 2) p-block (groups 13 to 18), d-block ( groups 3 to 12), f-block (lanthanides and Actinides).

 

 

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