Question

An element X has two isotopes. X-15 has 7 protons and 8 neutrons.determine the atomic number and mass Number of the second isotope,which has 10 neutrons in its nucleus

Answer 1

Answer:

For isotope we can say

Atomic Number = Number of protons = 7

Number of neutrons = 10

So isotope is given as X-17

Explanation:

As we know that isotope is defined as the atoms which have same number of protons but different number of Neutrons

So isotopes must have same atomic number or same number of protons

But since they have different neutrons so they must have different mass number

So here we can say

it must have atomic Number = Number of protons = 7 protons

Number of Neutrons = 10

Mass Number = Number of Neutrons + number of protons

Mass Number = 7 + 10 = 17

So it is given as X-17

Answer 2

Atomic Number is 7, because isotopes contain the same number of protons. The mass number is 17, because protons + neutrons = mass number.