state the connection between the number of valence electrons and group number in the periodic table
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Answer:
Location of Elements in Periodic Table
Location of elements in the periodic table is related to its number of valence electrons. Valence electrons are the outermost shell electrons in an atom. Elements in the same group have the same number of valence electrons and similar electronic configurations. The group number (1A-8A) is equal to the number of valence electrons for main group elements (except Helium). The chemical properties of a group are similar because they contain same number of valence electrons and configurations. Thus the periodic table is organized into groups of elements with similar valence electronic configurations in the same column.
In the table below, we are trying to see electronic configuration of alkali metals.
It is evident from the table that all elements in group IA end with s1 configuration for the valence electrons (outermost shell). Similarly, all halogens valence configuration end with s2p5 configuration.
Considering electronic configuration, the periodic table can be classified in four blocks. The blocks are named according to the subshells that are filled with last electron of that element.
s block: Group IA and 2A, filling up s1-2 electrons.
p block: Group 3A-8A: filling up p1-6 electrons.
d block: 10 columns of transition metals, d1-10 electrons are filled up.
f block: two groups of 14 inner transition elements, f1-14 electrons are filled up
Electronic configuration of any element can be determined from the following table.