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Reviewing the Basics

Reviewing the Basics. Chapters 1-3. Pre-Test. Use this practice test to review chemical skills from your previous chemistry class. Search the internet or use your old chemistry notes for help in areas where you have difficulties. You may get help from others or ask me for help.

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Reviewing the Basics

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  1. Reviewing the Basics Chapters 1-3

  2. Pre-Test • Use this practice test to review chemical skills from your previous chemistry class. • Search the internet or use your old chemistry notes for help in areas where you have difficulties. You may get help from others or ask me for help. • For all calculated values, include correct units. • Use your periodic table, ions, and list of standards and equations.

  3. Pre-Test • DON’T GUESS! THE POINT OF THIS ACTIVITY IS TO FIND OUT WHAT YOU DON’T KNOW AND LEARN IT!!!! • Organize your work on a separate page where more space is needed. Be able to find this work when reviewing the problems. • DUE FRIDAY

  4. Housekeeping • Pencil sharpener, stapler, tape, hole punch • Recycling • Kleenex, hand sanitizer, anti-bacterial soap

  5. UNITS • Important to convert back and forth between metric and English systems • Mass 1 lb = 0.4536Kg = 453.6g • Volume 1 qt = 0.9464 dm3 = 0.9464L • Length 1 inch = 2.54 cm (exact) • °C = 5/9(°F – 32) • °F – 9/5(°C) + 32 • Also K = °C +273.15

  6. MEASUREMENTS - SigFigs Imagine a map of the United States and superimpose the measurement on top. If a decimal point is present in the number, count significant digits from the Pacific side. (If decimal point is present, count from thePacific side.) If a decimal point is absent, count from the Atlantic side. You should start counting with the first nonzero digit you find. Thereafter, all digits, including zero, are significant.

  7. MEASUREMENTS - SigFigs 1. Digits other than zero are always significant. 2. One or more final zeros used after the decimal point are always significant. 3. Zeros between two other significant digits are always significant. 4. Zeros used solely for spacing the decimal point are not significant. The zeros are place holders only.

  8. MEASUREMENTS - calculating ADDITION and SUBTRACTION • The number of significant figures to the right of the decimal point in the final sum or difference is determined by the lowest number of significant figures to the right of the decimal point in any of the original numbers. MULTIPLICATION and DIVISION • The number of significant figures in the final product or quotient is determined by the original number that has the smallest number of significant figures.

  9. MEASUREMENTS - important • 1. Carry as many numbers as possible throughout the calculation and only round off the final answer. • The use of an improper number of significant figures may lower your score on the AP exam. • Remember the different between measured values and exact values.

  10. ACCURACY AND PRECISION

  11. DIMENSIONAL ANALYSIS • An efficient way to do mathematical calculations where units are cancelled until only the desired unit is left. • Always start with what you know. • Sometimes on the AP exam, only set-ups will be given as possible answers. Write the correct set-up to the problem and then see which one of the answers represents your answer. • UNITS MUST CANCEL.

  12. FUNDAMENTAL LAWS • Law of Conservation of Mass – matter can be neither created or destroyed but can be converted from one form to another. • Law of Definite Proportion – compounds always have constant composition, ratio of elements to each other. • Law of Multiple Proportions – When two elements form a series of compounds, the ratio of the masses of the second element that combines with one gram of the first element can always be reduced to small whole numbers.

  13. STRUCTURE OF THE ATOM • First modern theory was developed by John Dalton • J.J. Thomson discovered the electron and developed the plum pudding model. • Robert Millikan measured the electric charge and the mass of an electron. • Ernest Rutherford discovered the proton and the nucleus.

  14. STRUCTURE OF THE ATOM • Proton, p+: positive charge, 1.007 amu, located in the nucleus, mass of 1.673 x 10-24g • Neutron, n°: neutral charge, 1.009 amu, located in the nucleus, mass of 1.675 x 10-24g • Electron, e-: electron charge, 5.486 x 10-4amu, located outside the nucleus, mass of 9.109 x 10-24g

  15. ATOMS, MOLECULES, IONS • Atom – the smallest part of an element that retains all the properties of that element. • Molecule – a covalently bonded compound. • Ion – an atom the has gained or lost electrons and gained a positive of negative charge as a result. • cation = positive ion and anion = negative ion.

  16. PERIODIC TABLE BASICS • Periods (rows), groups/families • Metals, nonmetals, metalloids • Alkali metals, alkaline earth metals, halogens, noble gases • Transition elements, inner transition elements • Valence electrons • s, p, d, f blocks

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