Rutherford's alpha-particle scattering experiment on a thin gold foil led to which conclusion?
- A.Electrons are embedded in a sphere of positive charge
- B.The atom is indivisible
- C.Electrons revolve in fixed permitted orbits
- D.Almost all the mass and the positive charge lie in a tiny nucleus
Correct answer
Explanation
The correct answer is D, almost all the mass and the positive charge lie in a tiny nucleus. Most alpha particles passed straight through the foil, a few were deflected through small angles and about one in twenty thousand bounced back. Rutherford read this as meaning that the atom is mostly empty space, that its positive charge and nearly all its mass are packed into a very small central nucleus, and that electrons move around it. Option A is wrong because that is Thomson's plum pudding model, which the experiment disproved. Option B is wrong because indivisibility was Dalton's postulate, already broken by the discovery of the electron. Option C is wrong because fixed permitted orbits came later, with Bohr, who introduced them to cure the instability in Rutherford's own model.
Read the full article: Atomic Structure and Periodic Table: Models and Trends
Practice Questions
View allWho coined the word 'atom'?
- A.Democritus
- B.Thomson
- C.E Rutherford
- D.John Dalton
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The Greek philosopher Democritus, working in the fifth century before the common era, argued that matter could be divided only up to a limit, and he called that smallest indivisible particle atomos, from which the word atom comes.
Read the full explanation →Who among the following discovered the neutrons?
- A.J. Chadwick
- B.E. Goldstein
- C.Neils Bohr
- D.Ernest Rutherford
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James Chadwick discovered the neutron in 1932 by bombarding beryllium with alpha particles and showing that the radiation produced consisted of neutral particles of nearly the same mass as the proton.
Read the full explanation →The maximum number of electrons that can be accommodated in the M shell is:
- A.8
- B.2
- C.18
- D.32
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The capacity of a shell is given by the formula 2n squared, where n is the number of the shell counted outward from the nucleus.
Read the full explanation →Alkali metals are assigned which group in the Modern Periodic Table?
- A.Second group
- B.Eighteenth group
- C.Third group
- D.First group
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The alkali metals are lithium, sodium, potassium, rubidium, caesium and francium. Each has a single electron in its outermost shell, loses it readily to form a positive ion, and therefore stands in group 1 of the modern periodic table.
Read the full explanation →Which of the following elements has the highest electronegativity?
- A.Fluorine
- B.Bromine
- C.Iodine
- D.Chlorine
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Electronegativity is the tendency of an atom to attract a shared pair of electrons towards itself. It increases from left to right across a period, as nuclear charge grows, and decreases down a group, as each new shell puts the outer electrons further from the nucleus.
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