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Monica Singh =)

By psharmaims
  • 460 BCE

    Democritus

    Democritus
    Democritus was a Greek philosopher who proposed the idea that matter is made of tiny, indivisible indestructible particles that he called atomos, From the English word atom which means indivisible. But his idea was rejected because he did not have the necessary equipment to test his ideas by using controlled experiments so that's why his idea was rejected.

  • John Dalton

    John Dalton
    John Dalton, a British chemist and physicist, developed a theory that matter is simply composed of atoms of different weights and is combined in ratios by weight. Also proposed that these atoms are spherical, and are in motion. All elements are composed of atom and all of the same elements are alike also atoms of different elements are different.https://www.youtube.com/watch?v=HFF-2wyyTKc

  • J.J Thompson

    J.J Thompson
    J.J Thompson was a English scientist. He discovered the electron when he was experimenting with gas discharge tubes.He unearthed a new movement in the tube, he called it the movement in cathode rays. The rays moved from the negative end of the tube to the positive end. He realized that the rays were made of negatively charged particle-electron.https://www.youtube.com/watch?v=1QXzfO00yjM

  • Lord Ernest Rutherford

    Lord Ernest Rutherford
    Ernest Rutherford conducted a famous experiment called the gold foil experiment. In his experiment he used a thin sheet of gold foil.he also used special equipment to shoot alpha particles ( positively charged particle). His experiment helped him discovered the nuclear atom, which meant that atoms had a positive charged center surrounded by negative charged particle.

  • Neils Bohr

    Neils Bohr
    Neil Bohr was a Danish physicist. He proposed a model similar to solar system . The electrons go around the nucleus like planets orbit around the sun. All electron have their energy levels- a certain distance from the nucleus. Each energy level can hold a certain number of electron. Level 1 can hold 2 electron, level 2 - 8 electrons,level 3 - 18 electrons, and level 4 - 32 electrons. when electrons lose energy, they go down a level. When it gain energy it goes down a level.