Fill in the blanks in the following statements
(a) Rutherford’s α-particle scattering experiment led to the discovery of the __________
(b) Isotopes have same _______ but different _______
(c) Neon and chlorine have atomic numbers 10 and 17 respectively. Their valencies will be _____ and _____ respectively.
(d) The electronic configuration of silicon is ______ and that of sulphur is _____
(a) The Rutherford’s α-particle scattering experiment led to the discovery of the atomic nucleus.
Rutherford’s alpha scattering experiment gave the model of the atom with a positively charged nucleus in the center.
(b) Isotopes have same atomic number but different mass number.
For example, Hydrogen has three isotopes, protium (H11), deuterium (H21 or D21) and tritium (H31 or T31). The chemical properties of isotopes are similar but their physical properties are different.
(c) Neon and chlorine have atomic numbers 10 and 17 respectively. Their valencies will be 0 and 1 respectively.
Neon has 8 electrons in its outermost shell. Its octet is complete. It does not have to gain or lose any electron. Hence, its valency is zero.
In case of chlorine, it has 7 electrons in its outermost shell. It can gain an electron to complete its octet. Hence, the chlorine atom gains an electron to become an ion with -1 charge. Therefore, the valency of chlorine atom is 1.
(d) The electronic configuration of silicon is 2, 8, 4 and that of sulphur is — 2, 8, 6.
The atomic number of Silicon is 14 and the atomic number of sulphur is 16.