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Science 9 Gandha Name: _____________________________ Date: ___________________ Blk: ______________ 1.3 Atomic Theory Notes Objectives By the end of the lesson you should be able to: • Describe _______________ the atomic theory was developed and _____________ was involved in the process • Draw and describe an atom using ____________________________________________ Historical Understanding • ____________________: world was based on _____________________________ (earth, water, fire, metal and wood) Historical understanding • ___________________________: argued that matter could be endlessly divided until reaching the ________________________ (smallest piece) • We use the word _____________________________ today from this origin Historical understanding • Aristotle did not agree; he believed • ______________________________________________________________ • Nobody challenged the idea again for ______________________________________ • Alchemists in the Middle Ages tried to turn common metals into gold - nobody succeeded! • They tried for _____________________________________! Atomic Theory Development • The Revolution! • John Dalton, J.J. Thomson, Ernest Rutherford and Niels Bohr all played a very important part in the _______________________________________________________________ John Dalton (1766 – 1844) Dalton’s Atomic Theory: 1. All matter is made up of small particles called _________________________________ 2. Atoms cannot be ________________________________________________________ _____________________________ into smaller particles 3. All atoms of the ___________________________________________________ are identical in mass and size but they are different in mass and size from atoms of other elements 4. Compounds are created when atoms of different elements ____________________________________________ in definite proportions Science 9 Gandha J.J. Thomson (1856 – 1940) • Used ____________________________________________________ in gas discharge tubes to determine that currents were ______________________________ charges • Found all substances could produce these currents so all substances had negative charges • Atoms therefore had smaller negative charges J.J. Thomson (1856 – 1940) • Proposed the “______________________________________” or “Plum Pudding Model” Ernest Rutherford (1871 – 1937) • Student of J.J. Thomson • Shot positive (alpha) particles at a piece of gold foil and saw that some bounced off while most went straight through • Discovered ______________________________________________________________ _____________________________ (dense positively charged centre of an atom) • Nucleus is made of positive charges and neutral charges Niels Bohr (1885 – 1962) • Worked under Rutherford and knew that around the nucleus were negative charges • Found that gases would glow if an electric current passes through them (i.e. Neon signs) • Negative charges have certain amount of ____________________________________ Atomic Structure • Atom: smallest part of an element that keeps the properties of the element • Is made up of 3 smaller sub-atomic particles • ________________________________________________ • ________________________________________________ • ________________________________________________
