One radioactive isotope of calcium has an atomic mass of 47,how many neutrons are in the calcium -47 nucleus

27 neutrons

Explanation:

Recall that the number of protons in the nucleus of an atom = Atomic number.

Hence, Calcium with mass number 47 and atomic number 20 will have 20 protons

Therefore, since Mass number = number of protons + neutrons

47 = 20 + neutrons

Neutrons = 47 - 20 = 27

Thus, there are 27 neutrons in radioactive calcium nucleus.

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.