Properties of atoms

Physical Science - Middle School

Properties of atoms

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Properties of atoms

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Study Guide Properties of atoms Physical Science - Middle School

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THE PROPERTIES OF ATOMS An atom is the smallest part of an element that has all the properties of that element. In other words, one atom of oxygen behaves like a whole cylinder of oxygen. History of the Atom As time has passed, ideas about the structure of an atom have changed. One of the first proposed atomic models was thought of by J.J. Thompson. He thought an atom was like a ball with both positive and negative charges in it. In the early 1900s, Rutherford proposed that atoms had a nucleus or positive center. He named the positively charged particles protons. According to Rutherford, most of an atom was empty space with the negatively charged particles, electrons, moving randomly around the nucleus. A few years later, Niels Bohr suggested that the electrons had specific paths or orbits as they moved around the nucleus. The movement of these electrons was much like the way the earth moves around the sun. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.
Current Model of the Atom The modern atomic model which is the current model, suggests that an atom has two particles in the nucleus, a proton and a neutron or neutrally charged particle. All the mass of an atom is made up with these particles. The total number of protons and neutrons in an atom is called atomic mass while the number of protons is called the atomic number. Lesson Checkpoint: What is the difference between atomic mass and atomic number? Electron Cloud The modern model also removes the idea that electrons move only in specific orbits. Instead, there is an electron cloud around the nucleus with the electrons moving in various directions. Lesson Checkpoint: How does the modern model of the atom differ from the earlier models? © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.