(a) The elements listed below to the same group in the Periodic Table \(_9F\) \(_{17}CI\) \(_{35}Br\) \(_{53}I\). (i) Write the electronic structure of the ...

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(a) The elements \(_9\text{F}\), \(_{17}\text{Cl}\), \(_{35}\text{Br}\) and \(_{53}\text{I}\) all belong to Group VII of the Periodic Table.

(i) The first member is fluorine (atomic number 9). Its electronic structure is:

\[ \text{F}: 1s^2\,2s^2\,2p^5 \quad \text{(i.e. } 2,7). \]

(ii) The family name of the elements is the halogens.

(iii) Fluorine (F) has the strongest oxidizing ability. Oxidizing power decreases down the group as atomic size increases and the ease of gaining an electron falls; fluorine, being the smallest, attracts an incoming electron most strongly.

(b)(i) The chloride that exists as discrete molecules is BCl₄ (a covalent chloride, existing as separate molecules with low melting and boiling points).

(b)(ii) The bonding that holds atoms of A and chlorine together in ACl is ionic (electrovalent) bonding, formed by the transfer of an electron from the metal A to chlorine.

(b)(iii) The chloride that is a good conductor of electricity (when molten or in aqueous solution) is ACl, because it is ionic and contains free-moving ions.