Question

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1. the following elements belong to the same group of the periodic table. (letters do not represent t actual symbols).

(a) are the elements metals or non - metals? explain
(b) which of the element is the most reactive?

Explanation:

(a)

Metals have relatively low first ionization energies (compared to non - metals). The first ionization energies of these elements (736 kJ/mol for A, 900 kJ/mol for B, 590 kJ/mol for C) are in the range typical for metals. Also, when metals form ions, they lose electrons. For example, if we assume they form cations, the ionic radius is smaller than the atomic radius (as seen in the data: atomic radius > ionic radius for A and B).

(b)

In a group of metals (assuming these are in the same group), reactivity increases down the group. As we move down a group, the atomic radius increases. The outermost electrons are less tightly held. Element C has the largest atomic radius among the three. So, it will lose electrons more easily (lower first ionization energy compared to A and B in a group trend context, assuming the trend of decreasing first ionization energy down a group for metals).

Answer:

(a) Metals. Low first ionization energies and atomic radius > ionic radius (for cation formation).
(b) Element C.