By considering their position in the Periodic Table,which one of the following elements would you expect to have maximum metallic characteristic?
$Ga$,$Ge$,$As$,$Se$,$Be$

Why do you think the noble gases are placed in a separate group?

Helium is an unreactive gas and neon is a gas of extremely low reactivity. What,if anything,do their atoms have in common?

What were the limitations of Newlands' Law of Octaves?

The position of three elements $A$,$B$ and $C$ in the Periodic Table are shown below:

Group $16$	Group $17$
-	-
-	$A$
-	-
$B$	$C$

$(a)$ Will $C$ be larger or smaller in size than $B$?
$(b)$ Which type of ion,cation or anion,will be formed by element $A$?

Which element has
$(a)$ a total of three shells,with four electrons in its valence shell?
$(b)$ a total of two shells,with three electrons in its valence shell?
$(c)$ twice as many electrons in its second shell as in its first shell?