The periodic law based on increasing atomic number, rather than atomic mass, is credited to whom?
- A.Dmitri Mendeleev
- B.Henry Moseley
- C.John Newlands
- D.Johann Dobereiner
Correct answer
Explanation
The correct answer is B, Henry Moseley. His study of the characteristic X-rays of the elements showed that the nuclear charge, the atomic number, is the quantity that rises regularly from element to element, and the modern periodic law therefore states that properties are a periodic function of atomic number. Option A is wrong because Mendeleev built his table on increasing atomic mass, left gaps for undiscovered elements and predicted their properties, but his basis needed the correction Moseley supplied. Option C is wrong because Newlands proposed the law of octaves, in which every eighth element resembled the first. Option D is wrong because Dobereiner gave the law of triads, in which the middle member of a group of three had roughly the average mass of the other two. The three early attempts run Dobereiner, Newlands, Mendeleev, then Moseley.
Read the full article: Famous Scientists and Their Laws and Discoveries
Practice Questions
View allAccording to which theory or law can any object with mass not travel as fast as the speed of light in empty space, that is in vacuum?
- A.Dalton law
- B.Corpuscular theory of light
- C.Theory of relativity
- D.Henry law
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In Einstein's special theory of 1905 the energy required to accelerate a body with mass rises without limit as its speed approaches that of light, so such a body can come close to but never reach the speed of light in vacuum, which is the same for every observer.
Read the full explanation →Who discovered the electron?
- A.Ernest Rutherford
- B.J.J. Thomson
- C.James Chadwick
- D.Niels Bohr
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Thomson. Working with cathode rays in a discharge tube in 1897, he showed that the rays were a stream of negatively charged particles far lighter than any atom, and he measured their charge to mass ratio, which established the electron as the first known subatomic particle.
Read the full explanation →The neutron was discovered in 1932 by which scientist?
- A.James Chadwick
- B.Eugen Goldstein
- C.Max Planck
- D.Werner Heisenberg
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By bombarding beryllium with alpha particles he obtained a penetrating radiation that could not be bent by electric or magnetic fields, and he showed it to consist of neutral particles of about the mass of a proton, for which he received the Nobel Prize in Physics.
Read the full explanation →The three laws of planetary motion were given by whom?
- A.Nicolaus Copernicus
- B.Galileo Galilei
- C.Johannes Kepler
- D.Isaac Newton
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Working on the observations of Tycho Brahe he found that a planet moves in an ellipse with the sun at one focus, that the line from the sun to the planet sweeps equal areas in equal times, and that the square of the orbital period is proportional to the cube…
Read the full explanation →Hydraulic brakes in a motor car work on which principle?
- A.Archimedes principle
- B.Pascal law
- C.Bernoulli principle
- D.Hooke law
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Pressure applied to an enclosed liquid is transmitted equally and undiminished in every direction, so a small force on the narrow master cylinder of a brake creates a much larger force on the wide piston at each wheel, which is also how a hydraulic press and a hydraulic lift work.
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