Grade 11- History of Chemistry.docx - Permanentlyn...

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Permanentlyn intentionallyHe has fewer lines in the spectrum than xenon has because xenon has more number of electrons andthey occupy more orbitals. Each charge in the energy level results in a different colour emitted by thespectrum1) Democritus: His theory: Matter could not be divided into smaller and smaller pieces forever, eventuallythe smallest possible piece would be obtained. This piece would be indivisible. He named the smallestpiece of matter “atomos,” meaning “not to be cut.”To Democritus, atoms were small, hard particles that were all made of the same material but weredifferent shapes and sizes. Atoms were infinite in number, always moving and capable of joiningtogether.DALTON: He proposed the Atomic theory of matter based on his experimental observations. He had noknowledge of the subatomic particles, he had thoughts no experiment, he related his theory to a billiardball model. The main postulates of Dalton’s atomic theory are as follows.All matter is made of atoms. Atoms are indivisible and indestructible.All atoms of a given element are identical in mass and properties.Compounds are formed by a combination of two or more different kinds of atoms.A chemical reaction is a rearrangement of atoms.Atoms can be neither created nor destroyed.Thomson's atomic theory proposed a model of atom which is known as plum pudding model orChristmas pudding or chocolate chip cookie model. Thomson’s atomic theory suggested that the atom isnot indivisible as it was of smaller pieces – electrons and protons. An atom consists of a sphere ofpositive charge with negatively charged electron embedded in it. The positive and the negative chargesin an atom are equal in magnitude, due to which an atom is electrically neutral. It has no over allnegative or positive charge. Now Thomson thought of a new approach. A charged particle will normallycurve as it moves through an electric field, but not if it is surrounded by a conductor (a sheath of copper,

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Term
Spring
Professor
professor_unknown
Tags
Atom, Electron, Electrons

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