Exercise 1.1 Atoms and Molecules (number 1 to 3)

Answers:

1. Relative mass of these sub-atomic particles :

• Proton : 1 a.m.u
• Eletron : 1/1834 a.m.u
• Neutron : 1 a.m.u

The proton is heavier than the electron because the electric charge depends on the mass time the radius of a particle and whereas the mass of the proton is heavier than the mass of electron. Thus, the product of mass time the radius is in both particles are the same and therefore they have the same charge.

2. The number of protons, neutrons, and electrons for each isotope.

²⁴⁴₉₄ Pu > Protons : 244

Neutrons : 94

Electrons : 150

⁵⁶₂₆ Fe ³⁺ > Protons : 56

Neutrons : 26

Electrons : 30

⁷⁸ ₃₄ Se^2- > Protons : 78

Neutrons : 34

Electrons : 44

3. An isotope consists of 33 protons and 42 neutrons.

³³₄₂M