Features of mordern periodic table
Answers
Answer :
Henry Moseley made his contribution in chemistry as modern period table in 1913. It showed that atomic number of an element is more fundamental property than its atomic mass. He modified the Mendeleev's periodic table and formulated the modern periodic law as " The properties of elements are periodic functions of their atomic masses " .
The features of modern periodic table are :
i) The periodic table is divided into 18 vertical columns,known as groups and 7 horizontal rows known as periods.
ii) The elements present on the Groups have same number of electrons in their valence shell of their atoms.
iii) Elements present in the same group have same valency.
iv) The atomic radii, increases down the group and decreases along the period.
v) The number of electrons distributed in different shells are based on the formula of 2n^2 , where n= number of shells.
vi) Valency is determined by the number of electrons present in the outermost shell.
vii) Metallic Character increases down the group and decreases along the period.
viii) Non - metallic character increases along the period and decreases down the group.
ix) Ionisation enthalpy and electron gain enthalpy increases along the period and decreases down the group.
x) One electron gets added to the same shell of elements across a period from left to right and one shell gets added to the atom of each element down the group.