Answer: K and Br
Explanation: Ionic compounds are formed by the transfer of electrons between metals and non metals.
Electronic configuration of potassium:
[tex]K:19=1s^22s^22p^63s^23p^64s^1[/tex]
Potassium atom will loose one electron to gain noble gas configuration and form potassium cation with +1 charge.
[tex]K^+:18:1s^22s^22p^63s^23p^6[/tex]
Electronic configuration of bromine:
[tex]Br:35=1s^22s^22p^63s^23p^64s^23d^{10}4s^24p^5[/tex]
Bromine atom will gain one electron to gain noble gas configuration and form bromide ion with -1 charge.
[tex]Br^-:36:1s^22s^22p^63s^23p^64s^23d^{10}4s^24p^6[/tex]
In potassium bromide [tex](KBr)[/tex] ,one electron from potassium metal gets transferred to bromine atom.
