Question

If E³⁺ is the cation of an element 'E', and has 10e⁻,then what is the atomic number and mass number of element 'E'?

Answer 1

Answer:

No of electrons in M  

2+

ion =10

No of electrons in M = 12

∴ No of protons = No of electrons = 12

∴ Atomic no = 12

Mass number = Atomic number + No of protons = 12+12=24

Explanation:

Answer 2

Answer:

Atomic number of element E will be 13

Atomic mass of element E will be 27

Explanation:

1) We know that the atomic number is the total number of protons in an atom and in a neutral atom, the number of protons is equal to the number of electrons.

2) So, ion E³⁺ formed after losing three electrons which tells us about the total number of electron or proton in neutral atom would be 13.

3) Hence, the atomic number will be 13.

4) So the element is Aluminium ( Al )

5 Atomic mass will be = neutron + proton

We know that number of neutrons in aluminium is 14

So,

Atomic mass of Aluminium will be = 14 + 13 = 27