The Fundamental Unit of Life
How was it shown that atomic nuclei are positively charged?
Or
Describe an experiment to show that the nucleus of an atom contains positively charged particles.
The fact that atomic nuclei are positively charged can be shown by performing Rutherford’s α-particle scattering experiment. Take a thin sheet of metal foil. Allow α-particles to bombard over it. It will be observed that only a small fraction of α-particles (positively charged) are deflected through large angles and the rest pass through the foil without any deflection. This shows that positive charge of the atom is concentrated at the centre or the nucleus.
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Na+ has completely filled K and L-shells. Explain.
If Z = 3, what would be the valency of the element? Also, name the element.
Composition of the nuclei of two atomic species X and Y are given as under
X Y
Protons = 6 6
Neutrons= 6 6
Give the mass numbers of X and Y. What is the relation between the two species?
For the following statements, write T for True and F for False.
(a) J.J. Thomson proposed that the nucleus of an atom contains only nucleons.
(b) A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.
(c) The mass of an electron is about 1/2000 times that of proton.
(d) An isotope of iodine is used for making tincture iodine, which is used as a medicine.
Rutherford’s α-particle scattering experiment was responsible for the discovery of
Isotope of an element has
Number of valence electrons in Cl- ion are
Which one of the following is a correct ? Electronic configuration of sodium
(a) 2, 8,2 (b) 8, 2, 1 (c) 2, 1, 8 (d) 2, 8, 1.
Complete the following Table:
Atomic number |
Mass number |
Number of neutrons |
Number of protons |
Number of electrons |
Name of the atomic species |
9 |
- |
10 |
- |
- |
- |
16 |
32 |
- |
- |
- |
Sulphur |
- |
24 |
- |
12 |
- |
- |
- |
2 |
- |
1 |
- |
- |
- |
1 |
- |
1 |
0 |
- |
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