Problem#40Nuclear Chemistry [Solved]

Ordinary Chemistry

Nuclear Chemistry

1-Only Valence electrons are involved; the identities of atoms involved do not change, only their combination or arrangement changes

Ex: 2H₂(g)  +  O₂(g)  →  2H₂O(g)

1-Atomic nucleus is involved in the reaction; the identity of the atom involved changes and new atom(s) is(are) created, and nuclear radiations are emitted: alpha (α), beta (β), and gamma (γ).

Ex: ²³⁸₉₂U →  ²³⁴₉₀Th  +  ⁴₂α (⁴₂He)

A new atom, ²³⁴₉₀Th, is formed and a particle called alpha (⁴₂α) which is identical to a Helium nucleus is emitted; the reaction is called radioactive decay or transmutation.

Atoms or Nuclei that undergo natural decay are called Radioactive Elements.

2-Energy involved is relatively low: hundreds of Kcal

2-Energy involved is enormous: about 1000 million times as large as an ordinary chemical reaction such as the combustion process

3-The rate of an ordinary chemical reaction is affected by external conditions such as pressure, temperature, etc.….

3-The rate of a natural decay is not affected by external conditions of pressure and temperature.

4-All Isotopes of the same chemical element are chemically identical, i.e. they react in the same way and cannot be distinguished by chemical techniques. They can be distinguished and separated by physical techniques.

4-Isotopes of the same chemical element differ in their radioactive properties. For isotopes of the same chemical element, one can show one kind of radioactivity, another show a different radioactivity, another show no radioactivity at all.

5-Fulfill the law of mass conservation

5-The energy changes in nuclear reactions are enormous compared with those of even the most energetic chemical reactions, so that they result in a measurable change of mass called “mass defect”. This confirms the mass-energy equivalence of Albert Einstein:

E = mc^2 where

E = energy/joules

m = mass/kg

c = speed of light in m/s

N.B: We are surrounded by substances undergoing nuclear reactions in the soil, building materials, etc... Even in our bodies we have radioactive elements such as Strontium-90 in our bones and Iodine-131 in our thyroids, both are β-emitters.