Module 3 The Structure of the Atom Vocabulary

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Dalton’s Atomic Theory

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States that matter is composed of extremely small particles called atoms; atoms are invisible and indestructible; atoms of a given element are identical in size, mass, and chemical properties; atoms of a specific element are different from those of another element; different atoms combine in simple whole-number ratios to form compounds; in a chemical reaction, atoms are separated, combined, or rearranged.

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Theory

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An explanation supported by many experiments; is still subject to new experimental data, can be modified, and is considered successful if it can be used to make predictions that are true.

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Atom

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The smallest particle of an element that retains all the properties of that element; is electrically neutral, spherically shaped, and composed of electrons, protons, and neutrons.

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Cathode Ray

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Radiation that originates from the cathode and travels to the anode of a cathode-ray tube.

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Electron

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A negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus.

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Nucleus

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The extremely small, positively charged, dense center of an atom that contains positively charged protons and neutral neutrons.

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Proton

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A subatomic particle in an atom's nucleus that has a positive charge of 1+.

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Neutron

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A neutral, subatomic particle in an atom's nucleus that has a mass nearly equal to that of a proton.

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Model

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A visual, verbal, and/or mathematical explanation of data collected from many experiments.

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Atomic Number

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The number of protons in an atom.