Question

atom with large atomic radii and low ionization potential are more metallic in nature give reason

Answer 1

The tendency of an element to lose electrons and form positive ions (cations) is called electropositive or metallic character. For example, alkali metals are the most electropositive elements.

As we move from left to right of the period, the electrons of the outer shell experience greater pull of the nucleus. This greater force of attraction is because the nuclear charge increases and the size of the atom decreases from left to right. Thus, elements to the left (with larger atomic radii) of the periodic table have a tendency of losing electrons easily as compared to those to the right and are metallic in nature. Hence even their ionization potential is low compared to elements on right (ionization potential increases from left to right of the periodic table).
E.g. in the third period, sodium has the largest atomic radii (low ionization potential) and chlorine the smallest (with high ionization potential).
Hence sodium is metallic while chlorine is non-metallic.

Answer 2

Atom with large atomic radii and low ionization potential are more metallic in nature
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1)if the atomic radii is larger the nucleus cannot hold the nucleus very tightly making it more easier  to remove it 

2)the energy required to remove an electron is called as as ionization enthalpy and across the period the ionization enthalpy will increase

3)if the ionization enthalpy is less it will more easier to remove an electron as less energy is required 

4)as metals are formed by the losing of electrons, it will be more easier when the atom has  large atomic radii and low ionization potential