1. Mendeleev came up with the first periodic table of elements by organizing the known elements based on their chemical properties and arranging them in order of increasing atomic mass. He noticed that when the elements were arranged in this way, certain patterns and similarities emerged.
2. J.J. Thomson's cathode-ray tube experiments disproved John Dalton's theory that atoms were indivisible and had no internal structure. Thomson's experiments showed that atoms contained subatomic particles called electrons.
3. Millikan's contribution to the understanding of electrons was the determination of the exact charge and mass of an electron through his famous oil-drop experiment. This experiment helped to establish the concept of quantized electric charge and provided precise measurements of the electron's charge.
4. The Coulomb force, also known as electrostatic force, describes the attraction or repulsion between charged particles. Like charges (positive-positive or negative-negative) repel each other, while opposite charges (positive-negative) attract each other. The strength of the force depends on the magnitude of the charges and the distance between them.
5. The observation by Ernest Rutherford and his students that refuted the plum pudding model was the highly-scattered alpha particles during their famous gold foil experiment. Instead of passing straight through the gold foil as predicted by the plum pudding model, some alpha particles were deflected at large angles, indicating the presence of a small, dense, and positively charged nucleus within the atom. This discovery led to the development of the modern atomic model.
1.How did Mendeleev come up with the first periodic table of the elements?
2.Which part of John Dalton’s theory was disproved by J.J. Thomson’s cathode-ray tube experiments?
3.Which information did Millikan contribute to the understanding of electrons?
4.How does the Coulomb force affect charge interactions?
5.Which observation by Ernest Rutherford and his students refuted the plum pudding model?
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1 answer