Theatomismostlyemptyspace

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Unformatted text preview: ve greater KE, then energy is released when the change in state occurs, and the physical change is exothermic. – To determine for chemical changes consider if the surrounding became hotter or colder after the reaction. CHEM139 Exam 1 Study Guide page 2 of 3 Chapter 4: Chemical Foundations: Elements, Atoms, and Ions • Know ideas of matter proposed by Democritus, Empedocles, and Aristotle. • Know the main points of John Dalton’s model, what was later proven wrong and why. • Know people and discoveries associated with the discovery of protons, neutrons, electrons. • Know Plum‐Pudding Model vs Nuclear Model • Know Rutherford’s Alpha Scattering Experiment and what was determined from it – Protons are concentrated in the atomic nucleus, and electrons are outside the nucleus. – The atom is mostly empty space. – The radius of an atom is about 10‐10 m, and the radius of its nucleus is about 10‐15 m. • Subatomic particles – proton (p+): +1 charge, inside nucleus – neutron (n): neutral, inside nucleus – electron (e–): –1 charge, outside nucleus • Electrostatic force: force resulting from a charge on particles – Objects w/ like...
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