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Sem 1 Final Review Chapters 1- 5

Sem 1 Final Review Chapters 1- 5. States of Matter. Fixed = solid Variable shape = liquid Variable shape and volume = gas. Physical vs. Chemical. Physical properties can be measured without changing the substance

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Sem 1 Final Review Chapters 1- 5

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  1. Sem 1 Final ReviewChapters 1- 5

  2. States of Matter • Fixed = solid • Variable shape = liquid • Variable shape and volume = gas

  3. Physical vs. Chemical • Physical properties can be measured without changing the substance • Examples: color, shape, mass, density, conductivity, malleability, melting point • Chemical properties are only apparent when the substance reacts • Examples: reacts with oxygen, burns, rusts, decomposes when heated

  4. Elements vs. Compounds • Elements have only one type of atom – they are listed on the periodic table • Examples: Ag, Cu, Br2, F2, S8 • Compounds have different types of atomscombined as molecules • Examples: CO, H2O, NH3

  5. Pure vs. Mixture • Pure substances are either elements (all same atom) or compounds (all the same molecules) • Mixtures must have more than one substance.

  6. Homogeneous vs.Heterogeneous • Homogeneous means the ‘same’ throughout • Allpure substances are homogeneous. • SOLUTIONS are homogeneous mixtures. • Examples: air, kool-aid, steel (Fe and C) • Many mixtures are heterogeneous, different areas have different properties • Example: chicken noodle soup

  7. Periodic Table • Families (columns) have similar characteristics • Important families: alkali metals, alkaline earth metals, halogens, noble gases • Most elements are metals because most elements have 1,2, or 3 outer electrons • Metals tend to lose electrons to become cations (+) when they form compounds

  8. Diatomic Elements • When these elements are alone and uncharged, they will exist as molecules H2N2 O2 F2 Cl2 Br2 I2

  9. Atomic Structure • The nucleus of an atom is made of protons and neutrons • It is positively charged and VERY small. • The electrons surround the nucleus and create an electron cloud. • The electron cloud is negatively charged and 10000x bigger than the nucleus. • Remember – you are mostly empty space.

  10. Atomic notation The bottom number is the ATOMIC NUMBER = number of protons. The top number is the MASS NUMBER = protons and neutrons Elements with the same # of protons but different # of neutrons are called ISOTOPES. Zn-65 p = 30n = 35 e = 30 Zn-66 p = 30n = 36 e = 30

  11. Ionic Compounds • Write the correct formula for these: • Sodium sulfide • Magnesium oxide • Iron(III) nitrate • Aluminum phosphate

  12. Ionic Compounds • Write the correct formula for these: • Sodium sulfide = Na2S • Magnesium oxide = MgO • Iron(III) nitrate = Fe(NO3)3 • Aluminum phosphate = AlPO4

  13. Naming Compounds • Write the name for these: • AlCl3 • CrCl3 • PCl3 • BeI2 • Cu(NO3)2 • NO2

  14. Naming Compounds • Write the name for these: • AlCl3 = aluminum chloride • CrCl3 = chromium(III) chloride • PCl3 = phosphorous trichloride • BeI2 = beryllium iodide • Cu(NO3)2 = copper(II) nitrate • NO2 = nitrogen dioxide

  15. Scientific Notation • Good notation has only one number before the decimal. • All of the digits shown in scientific notation are significant digits. Decimal notationScientific notation 0.003505 25500 4.2x103 2.50x10-2 3.505x10-3 2.55x104 4200 0.0250

  16. Significant Figures • Measure all the marks and estimate onedigit between the marks. • When you write the number, the last digit is always a ‘guess’ because its your estimate. • All the known digits and your estimate are the ’significantfigures’

  17. Counting Sig Figs • All non-zeros are sig figs (123456789) • Zeros at the beginning are never sig figs 0.00345 • Zeros bewteen numbers are always sig figs 42005 • Zeros at the end are only sig figs if there is a decimal point 37003700. 25.00

  18. Using Sig Figs • Sig figs allow us to round our answers correctly • When multiplying or dividing, round to the smallestnumber of sig figs in the problem • When adding or subtracting, round to the smallest number of places after the decimal (or the last column with sig figs for ever number in the problem.) 525.55 x 16.2 = 8513.91 (round to 3 sig figs) 8510 525.55 + 16.2 = 541.75 (round to 1 decimal) 541.8

  19. Dimensional Analysis • Use equalities to convert numbers/solve problems • Set-up so the units cancel • Multiply the tops, divide by the bottoms How many seconds in 3.25 hours? 60 min 60 sec (3.25)(60)(60) 3.25 hr 11700 sec = = X X (1)(1) 1 hr 1 min

  20. Density • Density = mass/volume • The density of water is 1 g/mL • Things that are more dense than water will sink in water. If there are less dense they will float on water. Put these objects in the cylinder of water. floats D = 0.80 g/mL 1.0 g/mL D = 1.25 g/cm3 sinks

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