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Chapter 3. Atoms: The Building Blocks of Matter. The Atom: From Philosophical Idea to Scientific Theory The Structure of the Atom Weighing and Counting Atoms. Dalton’s Atomic Theory. All matter composed of atoms
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Atoms:The Building Blocks of Matter • The Atom: From Philosophical Idea to Scientific Theory • The Structure of the Atom • Weighing and Counting Atoms
Dalton’s Atomic Theory • All matter composed of atoms • Atoms of a given element are identical in size, mass and other properties. Atoms of different elements are different. • Atoms can’t be created or destroyed. • Atoms combine in whole-number ratios in chemical compounds. • In chemical reactions, atoms are combined, separated, and rearranged.
Law of Multiple Proportions If two or more different compounds are composed of the same two elements, the masses of the second element combined with a certain mass of the first element can be expressed as ratios of small whole numbers.
The Isotopes of Hydrogen • Protium 1 proton 0 neutrons 1 electron • Deuterium 1 proton 1 neutron 1 electron • Tritium 1 proton 2 neutrons 1 electron
Atomic Numbers & Mass Numbers Atomic Number: (Z) The number of protons in the nucleus of each atom of that element Mass Number: total number of protons and neutrons in the nucleus of an isotope Nuclide: is a general term for any isotope of any element Isotopes: atoms of the same element with different masses
Steps for Solving Quantitative Problems • Read the problem carefully at least twice. Note any important descriptive terms that add meaning to the problem. • Your plan for solving a problem should show how the information given in the problem is used to find a solution. • Substitute the data and conversion factors into your plan from Step 2. • Always look back at your answer to determine if it is reasonable.
Optional Flow Chart Divide by molar mass Divide by 6.02x1023 Mass Mole Particle Multiply by molar mass Multiply by 6.02x1023