Question

For each of the following atoms or ions determine # protons, # electrons and #neutrons:

119Sn4+ # of protons___ # electrons____ #neutrons_____

201Hg # of protons____ # electrons ____ #neutrons_____

Answer 1

1. 119Sn⁴⁺

Mass no = 119

Mass no is the sum of no.of electrons + no. of neutrons

Now, atomic no of Sn = 50

Since, atomic no. = no. of protons =50

So, no. of neutrons = Mass no. - Atomic no. = 119-50 = 69

No. Of neutrons = 69

No.of electrons = no. of protons in a neutral atom

So, no. of electrons = 50-4(since +4 means lost 4 electrons)

= 46

2. 201Hg

Mass no = 201

Atomic no = 80

So, no of protons = no of electrons = 80

no. of neutrons = Mass no-Atomic no. = 201-80 = 121