Atom Dbq Essay

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What exactly is an atom? The atom is the basic building block of matter; also known as the smallest unit of all matter. Solids, liquids, gases, and plasma are all made up of atoms. Atoms are made up of protons, neutrons, and electrons; over time theories of the atom have changed and been perfected. The atom is made up of mostly empty space, but it still has many parts (Doc. 2). At the center is a positively charged ball of mass called the nucleus. Inside the nucleus are protons and neutrons. Protons are positively charged particles, and neutrons are particles with no charge (Doc. 3). The nucleus is surrounded by a cloud full of electrons (Doc. 3). Electrons are negatively charged particles (Doc. 3). They move around the nucleus in discrete regions called energy levels (OI). Protons and neutrons can be broken down into quarks …show more content…

Many scientists helped with this. In 465 B.C. Democritus named the atom “can’t be divided” (OI). He proposed that matter was made of atoms (Doc. 1). Later, Lavoisier introduced the Law of Conservation of Matter. It stated that matter couldn’t be created or destroyed. After that, John Dalton published the Atomic Theory of Matter in 1803 (Doc. 2). It said that matter is made of atoms that are too small to be seen by the naked eye, and that each type of matter is made of only one kind of atom (OI). J. J. Thomson observed electrons using cathode rays. A few years later, Ernest Rutherford bombarded an extremely thin piece of gold foil with positively charged alpha particles. Most of the protons passed through the foil, but some bounced off. Rutherford concluded that the atom must be composed of mostly empty space. He also realized that the alpha particles must have bounced off something else that had positive charge. The positively charged objects were protons. Neutrons were discovered by James Chadwick. To conclude, the theories of the atom have been modified a lot since the

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