Atomic Structure — Flashcards

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An atom is the smallest particle of matter that exhibits all the properties of an element. It is the building block of all types of matter and takes part in chemical reactions.

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Maharishi Kanada proposed that matter consisted of indestructible particles called paramanus, which combine to form anu, now called molecules.

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Democritus called the paramanu an atom. The word atom comes from the Greek word atomos, meaning indivisible.

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John Dalton described the atom as the smallest particle that exhibits all the properties of a particular element. Later research showed that many parts of Dalton's atomic theory were incorrect, but at…

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Atoms are divisible because they contain smaller particles called electrons, protons, and neutrons. These are called sub-atomic or fundamental particles.

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The three main sub-atomic particles are electrons, protons, and neutrons.

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An electron carries one unit negative charge equal to 1.602×10⁻19 coulombs. Its mass is 9.108×10⁻31 kg, which is about 1/1837 of the mass of a hydrogen atom.

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Electrons were discovered in 1897 by J.J. Thomson while studying cathode rays. Cathode rays consist of negatively charged particles called electrons.