question_answer

(a) The valence electrons in three elements R, A, J was found to be 1, 2, 3 respectively. Then, predict the nature of R, A, J. (b) The valence electrons in four elements A, R, T, I was found to be 4, 5, 6, 7 respectively. Then, predict the nature of A, R, T, I. (c) Identify an element which has one electron in K-shell but is a non-metal. (d) Identify an element that has two electrons in K-shell (other shells are empty, but is a noble gas.

Answer:

(a) The elements R, A, J are metals, since they can lose electrons to form cations. (b) The elements A, R, T, I are non-metals, since they can gain electrons to form anions. (c) Hydrogen (a) (d) Helium (b)