Answer the following questions-
1. Explain Daltons atomic theory
2. How were electron- cathode rays discovered
3. Write important characteristics of cathode rays
4. Explain Thomsons model of an atom
5. Write important characteristics of electron, proton and neutron
6. Explain Rutherfords – rays scattering experiment
7. Write observations of Rutherfords rays scattering experiment
8. What conclusion were derived about the nucleus of an atom from
Rutherfords rays scattering experiment
9. Explain Rutherfords model of an atom
10.Write failure of Rutherfords model of an atom
11.Explain about Bohrs model of an atom
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Answers
Answer:
Q.1
Ans;A theory of chemical combination, first stated by John Dalton in 1803. It involves the following postulates:(1) Elements consist of indivisible small particles (atoms).(2) All atoms of the same element are identical; different elements have different types of atom.(3) Atoms can neither be created nor destroyed.(4) ‘Compound elements’ (i.e. compounds) are formed when atoms of different elements join in simple ratios to form ‘compound atoms’ (i.e. molecules).Dalton also proposed symbols for atoms of different elements (later replaced by the present notation using letters).
(1) Elements consist of indivisible small particles (atoms).
(2) All atoms of the same element are identical; different elements have different types of atom.
(3) Atoms can neither be created nor destroyed.
(4) ‘Compound elements’ (i.e. compounds) are formed when atoms of different elements join in simple ratios to form ‘compound atoms’ (i.e. molecules).
Q۔4
Ans; Thomson atomic model, earliest theoretical description of the inner structure of atoms, proposed about 1900 by William Thomson (Lord Kelvin) and strongly supported by Sir Joseph John Thomson, who had discovered (1897) the electron, a negatively charged part of every atom. Though several alternative models were advanced in the 1900s by Kelvin and others, Thomson held that atoms are uniform spheres of positively charged matter in which electrons are embedded. Popularly known as the plum pudding model, it had to be abandoned (1911) on both theoretical and experimental grounds in favour of the Rutherford atomic model, in which the electrons describe orbits about a tiny positive nucleus
Q۔9
Ans;Rutherford's model shows that an atom is mostly empty space, with electrons orbiting a fixed, positively charged nucleus in set, predictable paths. This model of an atom was developed by Ernest Rutherford, a New Zealand native working at the University of Manchester in England in the early 1900s.
Q۔11
Ans۔In atomic physics, the Bohr model or Rutherford–Bohr model, presented by Niels Bohr and Ernest Rutherford in 1913, is a system consisting of a small, dense nucleus surrounded by orbiting electrons—similar to the structure of the Solar System, but with attraction provided by electrostatic forces in place of gravity