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The Fundamental Unit of Life
What are the similarities in the electronic structure of the following sets of atoms:No. of electrons in each atom is given in brackets:
i) lithium (3), sodium (11) and potassium (19).
ii) helium (2), neon (10) and argon (18).
iii)beryllium (4), magnesium (12), and calcium (20).
i) Lithium, sodium and potassium all have one electron in outermost shell. .
ii) Helium, neon and argon all have eight electrons in outermost shell.
iii) Beryllium, magnesium and calcium all have two electrons in outermost shell.
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Define valency by taking examples of silicon and oxygen.
Explain with examples, (i) Atomic number, (ii) Mass number, (iii) Isotopes, and (iv) Isobars. Give any two uses of isotopes also.
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
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