Question

(a) What is the relationship between two elements X and Y whose atomic numbers are 18 and 20 respectively but their mass numbers remain same as 40 ? (b) Are their chemical properties same or different ? Explain and support your answer. (c) Which has more number of electrons Na or Na1? Why ?

Answer 1

(b)no
(c) Na because Na1 will give one electron to become stable and hence the electron will remain in Na1 are 10
a) they are isobars

Answer 2

(a) The elements X and Y are isobars.

(b) Their chemical properties are different.

(c) Na has more electrons than $\bold{Na^+}$.

Explanation:

1. Isobars have same atomic mass but different atomic number.
2. Atomic number defines number of proton in the nucleus. If the atomic number are different then the atomic structure of the elements is also different. So, the elements have different chemical properties with same mass.
3. The "plus" sign in the sodium indicates that it lost an electron. So, the Na element has one more electron than $\bold{Na^+}$.