Question

Name
(a) three elements that have a single electron in their outermost shells,
(b) two elements that have two electrons in their outermost shells.
(c) three elements with filled outermost shells.
(a) Lithium, sodium, potassium are all metals that react with water
to liberate hydrogen gas. Is there any similarity in the atoms of
these elements?
(b) Helium is an unreactive gas and neon is a gas of extremely low
reactivity. What, if anything, do their atoms have in common?
Q.In the Modern Periodic Table, which are the metals among the first ten
elements?
By considering their position in the Periodic Table, which one of the
following elements would you expect to have maximum metallic
characteristic?
As
Se
Ge
Be
Ga​

Answer 1

Explanation:

(a) Lithium, sodium and potassium have single electron in their valence shell

(b) beryllium and magnesium

(c) Helium, neon and xenon have fully filled valence shells as they are noble gases

Lithium, sodium and potassium are group 1 elements and they are easily oxidised by giving 1 electron or we can say that their reduction potential is less than hydrogen electrode, due to which the reduce H+ ions to hydrogen gas and themselves get oxidised

Helium and neon, both are noble gases and have fully filled valence orbits, due to which there is no driving force for them to react and fulfill their octet.Hence they are unreactive

Among the first 10 elements, only lithium and beryllium are metals.