Question

An atom of element E contains 3 protons, 3 electrons and 4 neutrons:
(a) What is its atomic number?
(b) What is its mass number?
(c) Write the electronic configuration of the element E.
(d) State whether element E is a metal or non-metal. Why?
(e) What type of ion, cation or anion, will be formed by an atom of element E? Why?
(f) Write the symbol of the ion formed by an atom of element E.
(g) What could element E be?

Answer 1

a). Atomic number = Number of protons = 3
b). Mass number = Number of protons + number of neutrons =3 + 4 = 7
c). Electronic configuration of the atom is 2,1(K has filled with 2 and L has 1) or $1s^{2}2s^1$

d). It comes under s block element, $2s^1$, therefore it is alkali metal element

e). This alkali metal element has 1 valence electron in the outermost shell, it loses to form cation (positive ion).

f). The symbol of the ion E is $E^{+1}$

g). It is Lithium, Li.