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ATOM - Coggle Diagram
ATOM
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Dmitri Mendeleev's table is useful because it demonstrates how elements with similar physical and chemical properties.
Democritus- He developed the concept of the ‘Atom’, Greek for “indivisible”. He believed that everything in the universe was made up of atoms, which were microscopic and indestructible.
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Antoine-Laurent Lavoisier- He determined that the oxygen was a key substance in ‘combustion’, and he gave the element its name. He developed the modern system of naming chemical substances and has been called the “Father of modern chemistry”.
In the modern days, the word “alchemy” is associated with witchcraft, sorcery, mythical, creatures, and mystical images.
Joseph Louis Proust- A French chemist, best known for his discovery of the “Law of constant composition” in 1794. He formulated the “Law of definite proportions” which states that a compound always contains the same elements in certain definite proportions and in no other combinations.
Robert Boyle- The person who discovered that the volume of a gas decreases with increasing pressure and vice versa, the “Boyle’s Law”.
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The nucleus (center) of the atom, contains the protons (positively charged), and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).
Atoms consist of three basic particles; The ‘protons’, ‘electrons’, and the ‘neutrons’.
Most of the atom is empty space. The rest consists of a positively charged nucleus of protons and neutrons surrounded by a cloud of negatively charged electrons. The nucleus is small and dense compared with the electrons, which are the lightest charged particles in nature.
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(1) Billiard Ball Model of Atom- John Dalton theorized that matter was made up of many tiny particles called ‘atoms’ that had no parts. And he thought that atoms looked like “Billiard Balls”.
(2) Joseph John Thomson’s experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. Thomson proposed the “plum pudding model” of the atom.
(3) The impact of Ernest Rutherford’s “gold-foil experiment” showed that the atom consists of a small, massive, positively charged nucleus with the negatively charged electrons being at a great distance from the centre.
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The Bohr Model is a “planetary model” in which the negatively charged electrons orbit a small, positively charged nucleus similar to the planets orbiting the sun.
(5) Chadwick's Neutron Model In 1932, neutrons were found to have the same mass as protons which accounted for more of the mass of the atom.
(6) Wave Model/ Quantum Mechanical Model, the model proposes that electrons are almost as much like a wave of energy as they are like particles.
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