(a)   Nuclear charge : The charge on the nucleus is due to protons contained in it. The charge on each proton is + 1.6 x 10^-19 coulomb which is equal in magnitude to thecharge of an electron. Taking the charge of a proton as one unit, the total charge on the nucleus is numerically equal to the numberof protons. For example, a hydrogen nucleus (i.e., proton) carries a single unit charge.

(b)   Nuclear mass : As we may know that the mass of the nucleus is the sum of the masses of the neutrons and protons contained in it. This is expressed in terms of atomic mass unit (a.m.u.). One a.m.u. = 1.66 x 10^-27 kg. For example ₆C¹² nucleus has a mass of 12 a.m.u. so that its mass number A = 12.

It is assumed that the mass of the nucleus should be

                        Z m_p + N m_n

where m_p and  m_n are the masses of proton and neutron respectively

and Z is atomic number and N is the number of neutron.

Experimentally, it has been observed that

real nuclear mass < Z m_p + N m_n

The difference is assumed and real mass is called as mass defect.

(c)    Nuclear Radius : Rutherford with his experiment on α – particle scattering by thin metallic foils, concluded that the distance of the closest approach of the α – particle to the nucleus of the scatterer can be regarded as a measure of the size of the nucleus. He found this distance of the order of 10^-14 m.

It has been observed that volume of the nucleus is directly proportional to the number of nucleons A, i.e.

                                    Volume α A

Or                                4/3 π r³ α A

or                                 r³ α (3/4 π) A

or                                 r α (3/4 π)^1/3  A^1/3 = C (3/4π)^1/3 A^1/3

or                                 r = r₁ A^1/3

where r₁ is a linear constant and has an average value of 14 x 10^-15m. A is mass number of the nucleus. Radius of the nuclei of the carbon elements are given below:

Carbon (A = 12)

            r = 1.4 x 10^-15  x (12)^1/3 = 3.21 x 10^-15 m

These are the 3 important properties of nucleus. Next time we will discuss more properties of laser.

You may also read earlier article: Parts of nucleus.

The post 3 important properties of nucleus first appeared on Winner Science.

It is a known fact that from the scattering of α – particles, scientist Rutherford concluded that the atom of any element consists of central core called nucleus and electrons moving around it. The entire mass of the atom and positive charge is concentrated inside the nucleus. The nucleus is supposed to consist of two particles, the proton and the neutron. Their masses are nearly the same as :

                        Mass of the proton = 1.67261 x 10^-27kg

                        Mass of the neutron = 1.67492 x 10^-27kg

The proton is a positively charged particle while the neutron is a neutral particle, that is, it carries no charge. The charge on the proton is 1.6 x 10^-19 coulomb. Both the proton and neutron together in the nucleus are called nucleons . The number of protons in the nucleus is called the atomic number and the sum of protons and neutrons is called as mass number. The stability of a nucleus depends on the relative number of protons and neutrons.

The conventional symbols for nuclear species follow the following pattern

                        z X ^A

      where        X = Chemical symbol of the element

                        Z = Atomic number(i.e., number of protons in the nucleus)

      and                        A = Mass number (i.e., number of protons and neutron in the nucleus)

Therefore, the number of neutrons in the nucleus

                        N = A – Z

For example, ₁₅P³¹ has Z = 15 and A = 31

Therefore, the number of neutrons N =31 – 15 = 16

Number of electrons = 15

Number of protons = 15

The electrons move or one should say spin and revolve around nucleus like earth around sun. The electron stays in shells or orbits. The mass of the electron (9.108 x 10^-31 kg) is very very small.

The post Parts of nucleus first appeared on Winner Science.