The Fundamental Unit of Life
What observations led Rutherford to believe that central part of the atom is positively charged?
Rutherford designed a model in which fast moving alpha (a)-particles were made to fall on a thin gold foil. On the basis of above experiment Rutherford concluded that:
i) Most of the space inside the atom is empty because most of the (a)-particles passed through the gold foil without getting deflected.
ii) Very few particles were deflected from their path, indicating that the positive charge of the atom occupies very little space.
iii) A very small fraction of (a)-particles were deflected by 1800, indicating that all the positive charge and mass of the gold atom were concentrated in a very small volume with in the atom.
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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 |
- |
How do you establish that matter is electrical in nature?
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