PERIODIC TABLE

  In this article, I will discuss the Periodic table in detail.

       Elements are arranged in the periodic table on the basis of increasing atomic numbers. The elements arranged in horizontal rows in the tables are called periods. The elements arranged in vertical columns are called groups. The periodic table consists of 18 groups and 7 periods. Groups are divided into two further groups A and B. The symbol of each element is written in boxes along with the atomic number and atomic weight. Period no shows the no of energy shells around the nucleus of different elements. In the period, shell number remains the same but nuclear charge increases along the period.

Periods

·      1^st are seven periods in the periodic table. The first period starts with hydrogen (H) and ends with helium (He). It contains two electrons.

·      2^nd period starts with lithium (Li) atomic no 3 and ends with Ne (atomic number 10). It contains 8 elements (Li, Be, B, C, N, O, F, Ne).

·      3^rd period starts with sodium (Na) atomic no 11 and ends with argon (Ar) atomic number 18. It contains 8 elements, (Na, Mg, Al, Si, P, S, Cl, Ar.

·      4^th period starts with potassium (K) atomic number 19 and ends with krypton (Kr) atomic number 36. It contains 18 elements, (K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Kr).

·      5^th period starts with rubidium (Rb) atomic no 37 and ends with xenon (Xe) atomic number 54. It contains 18  elements, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe.

·      6^th period starts with cesium (Cs) atomic number 55 and ends with Lu atomic number 86. It contains 32 elements. There is an interruption in this period after lanthanum atomic number 57, 14 elements keep separated below the periodic table known as lanthanum series. These 14 elements have different properties from the remaining elements of their relevant period.

·      7^th period is still incomplete. Many new elements will discover in the future to complete this period. This period starts with francium (Fr). After actinium, 14 elements keep separated from their remaining elements of their period, below the periodic table, along with the lanthanum series, and this series is known as the actinides series.

Groups

 The vertical column of the periodic table is known as a group. The groups of the periodic table are divided into two groups A and B. A group is divided into 8 groups and B group is divided into 10 groups. Overall 18 groups are present in the periodic table. Group no tells us the total number of electrons present in an outermost shell or valence shell.

Group A

v      The elements of group IA is known as alkali metals.

v      The elements of group IIA is known as alkaline earth metal.

v      3^rd group IIIA include B, Al, Ga, In, Ti.

v      4^th group IVA include C, Si,  Gr, Sn, Pb. These elements are called chalcogens.

v      5^th group VA include N, P, As, Sb, and Bi.

v      6^th group include O, S, Se, Te, and Po.

v      7^th group include F, Cl, Br, I, and At. These elements are called halogens.

v      8^th group include He, Ne, Ar, Kr, Xe,  and Rn. This group is also known as the zero-group.

Group B

        The elements of group B are known as transition elements.

Ø IB includes Cu, Ag, Au, Unn.

Ø The group IIB includes Zn, Cd, Hg, and Pub.

Ø The group IIIB includes Sc, Y, La, and Ac.

Ø The group IVB includes Ti, Zr, Hf, and Rf.

Ø The group VB includes V, Nb, Ta, and Ha.

Ø The group VIB includes Cr, Mo, W,  and Sg.

Ø The group VIIB includes Fe, Tc, Re, and Ns.

Ø Three groups of transition series collectively called group no VIIIB. Ist group includes Mn, Ru, Os,  and Hs. 2^nd group include Co, Rh, Ir,  and Mt. 3^rd group include Ni, Pd, Pt, and Uuuu. 2

28 elements placed below the periodic table known as lanthanum and actinium series belong to period no 6 and 7 respectively.

Blocks

     The periodic table is divided into different blocks on the basis of filling of electrons in subshells of shells

ü Ist two groups belong to s-block because their last electron fills in the s-subshells.

ü Group 4 to 8 elements belong to p-block because their last electrons filled in p subshells.

ü The elements of group IB to VIIIB belong to d-block their last electron filled in d subshells.

ü The elements of lanthanides and actinides belong to f-block because their electrons filled in f sub-shells.