جميع المواضيع المتعلقة بـ ‘electropositive’

 

Astatin

Astatine A chemical element, At, atomic number 85. Astatine is the heaviest of the halogen groups, filling the place immediately below iodine in group 17 of the periodic table. Astatine is a highly unstable element existing only in short-lived radioactive forms. About 25 isotopes have been prepared by nuclear reactions of artificial transmutation. The longest-lived of these is 210At, which decays with a half-life of only 8.3 h….

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Four blocks of elements in the periodic table

Four blocks of elements in the periodic table.

1 –  s block elements. Elements of groups 1 and 2 each possessing one and two electrons respectively in the  s orbital of their outermost orbits are together known as  s block elements.

Example :                 Na:  1s2 2s2 2p6 3s1                   Mg:  1s2 2s2 2p6 3s2

Characteristics of s block elements.

a -They are metallic in nature…

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