ATPT - History of the Atom (Lesson)
History of the Atom
Introduction
All matter is made of atoms. In 470 BC Democritus suggested that a substance can be cut over and over to get to the tiniest piece of that substance that contains all of the properties of the larger piece. In doing so, he proposed the existence of an atom. The word atom comes from the Greek word "atomos" which means not-cut. Aristotle, an influential thinker, rejected the idea of the atom. Since his teachings were revered, the concept of the atom was lost for 2,000 years. In 1803, John Dalton resurrected the concept of the atom. Lord Rutherford refined the concept of atoms by explaining that atoms consist largely of empty space. After conducting his Gold Foil Experiment, Rutherford deduced that all atoms had a small dense positively charged center portion of particles (protons) and stated that negatively charged particles (electrons) surround the nucleus of positively charged particles and take up most of the space of the atom. Niels Bohr (Rutherford's student) refined Rutherford's planetary model of the atom by suggesting that electrons must exist in fixed paths or orbits. The Modern Model uses Bohr's idea of energy levels for electrons but does refer to the direct path of the electron. Instead, it speaks about the probability of finding an electron in a certain position.
In this lesson, we will take a closer look at the history of the atomic model and the scientists who played a major role in the development of the current model.ions you may come across in your day to day life. Did you know you can use the scientific method to help you with these questions and more?
Models of the Atom
In this segment of Chemistry Matters produced by Georgia Public Broadcasting, the students learn about different models of the atom, including Dalton’s model, Thomson’s model, Rutherford’s model, and the Bohr model. A note taking guide is available below. Feel free to pause the video at any time to take notes.
Click here to watch the VIDEO: Chemistry Matters Unit 3 Segment A Links to an external site.
Atomic Theory Timeline
Atomic Model: Show What You Know!
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