Chemistry CDA #1 Review

Math Review:

  • Know how to calculate density.
  • Understand the difference between accuracy and precision and why they are important in chemistry lab.
  • Be able to use significant figures appropriately when calculating answers. Review your rules!!!

Physical and Chemical Properties and Changes:

  • Know how to tell if a property is physical or chemical (can you observe it without changing it?). Understand why we need to know these properties.
  • Know how to determine if a change is chemical and physical and what indications to look for when determining this (Is it reversible? Did the properties change?)

Atomic Structure

  • For each subatomic particle we discussed, be able to describe its charge, relative size, importance and location in the atom. Be able to explain how the nucleus was discovered and what it is.
  • Know what gives an atom its identity
  • Be able to calculate mass numbers. Be able to show an element in Physicist’s Notation and Hyphen Notation.
  • Understand what an isotope is and the influence it has on atomic mass
  • Explain how fission can be used to create all elements larger than hydrogen
  • Know the difference between mass numbers and atomic masses. Be able to calculate an atomic mass from the mass of the isotopes and the percent abundance of each isotope.

Electrons in Atoms Review

  • History of Atomic Model: Know the differences between Rutherford, Thomson and Bohr’s atomic models. Be able to explain what was wrong with each of them and to draw a simple example for each. Be able to explain what ‘Quantized’ energy levels means.
  • Quantum Numbers: Know the proper names for each quantum number and what information they provide about the electron location. Know what Heisenberg’s uncertainty principle means. Be able to recognize the basic orbital shapes and know the number of different orientations of the various shaped orbitals. Understand what spin is and why it is necessary.
  • Aufbau Principle: Know what the Aufbau principle says and how we use it. Be able to apply it when writing electron configurations. Practice drawing that diagram!
  • Configurations: Be able to write proper electron, orbital and noble gas configurations for any element. Be able to draw Lewis Dot structures for any element that is not a transition metal. Be able to predict trends regarding valence electrons by looking at the periodic table.
  • Light & Atomic Spectra: Understand that different wavelengths of light have different energy. Be able to explain why atomic spectra prove that the energy in electron levels is quantized. Explain how atomic spectra are useful in identifying unknown substances.

PRACTICE PROBLEMS

1)How many significant figures are in each of the following?

  1. 19
  2. 910
  3. 5000.0
  4. 0.000720
  5. 606060
  6. 68400.20

2)Perform the following calculations and round your answer to the appropriate number of significant figures.

  1. 93.22 +18
  2. 72.8 - 70.4
  3. 107000 +190.079
  4. 446608.005 – 112230
  5. 6.92 x 7.9
  6. 8.245 x 9.00
  7. 4.46 / 6.52
  8. 9.825 / 8.20

3)A hot dog is cooked

  1. Chemical or physical change?
  2. Your reason:

4)Salt (NaCl) is dissolved in water

  1. Chemical or physical change?
  2. Your reason:

5)Water is boiled in preparation for making pasta

  1. Chemical or physical change?
  2. Your reason:

6)An element has three isotopes. The first isotope has a mass of 23.985 amu and an abundance of 78.99%. The second isotope has a mass of 24.986 amu and an abundance of 10.00%. The third has a mass of 25.983 amu and a mass of 11.01%. What is the element’s average atomic mass? What element is it?

7)Using the data on the table below, calculate the average atomic mass of Magnesium.

mass number / exact mass (amu) / relative abundance (%)
24 / 23.985042 / 78.99
25 / 24.985837 / 10.00
26 / 25.982593 / 11.01

8)Draw a simple sketch for Rutherford, Thomson, and Bohr’s atomic models. Explain why each model is no longer used.

9)Sketch an example of an s, p and d orbital.

10)Give the symbol for the atom whose electron configuration is shown below:

  1. 1s22s22p63s23p6b. 1s22s22p63s23p64s23d104p65s24d6 c. 1s22s22p63s23p64s23d8

#of protons / 32
#of neutrons / 30 / 32
#of electrons
Chromium-58 / Chromium-63
#of protons
#of neutrons
#of electrons

11)

12)

ELEMENT NAME / ION SYMBOL / #OF PROTONS / NUMBER OF ELECTRONS / #OF ELECTRONS LOST OR GAINED
ex / Fluorine / -
F / 9 / 10 / gainedone
1 / 53 / 54
2 / 16 / gainedtwo
3 / potassium / lostone
4 / Ca+2
5 / 35 / 36
6 / Sr+2
7 / H+
8 / 8 / gainedtwo

13) Calculate the %error in each problem

a)Samantha S. Sloppiness measured the volume of her soda before she drank it for her midmorning snack. She measured the volume of the 12 oz. bottle to be 14 oz.

b) Clyde Clumsy was directed to weigh a 500 g mass on the balance. After diligently goofing off for ten minutes, he quickly weighed the object and reported 458 g.

c)Pretty Patty Pestilence had casually recorded her grades for the nine weeks in her notebook. She concluded she had 250 points out of 300 for the grading period. However, Miraculous (chem teacher) determined she had 225 points out of 300 and awarded her a "C" for the grading period.

d)Drew D. Dingaling came to Miraculous with a problem. Drew was told to measure 50 cm of copper wire to use in an experiment. Since his ruler only measured to 45 cm he used this amount of wire and his experiment was a failure.

e)Henry Heavyfoot was just arrested for speeding by Officer O'Rourke for traveling 65 mph in a 55 mph zone. Henry claimed his speedometer said 55 mph not 65 mph.

f)Willomina Witty was assigned to determine the density of a sample of nickel metal. When she finished, she reported the density of nickel as 5.59 g/ml. However, Miraculous knew the density of nickel was 6.44 g/ml.

g)An experiment to determine the volume of a "mole" of a gas was assigned to Barry Bungleditup. He didn't read the experiment carefully and concluded the volume was 18.7 liters. Miraculous knew he should have obtained 22.4 liters.

Answers: a) 16.6% b) 8.40% c) 11.1% d) 10.0% e) 15.4% f) 13.2% g) 16.5%

14)

a)Which show a precise aim? Why?

b)Which show an accurate aim? Why?

Complete the following chart:

# Protons / # Neutrons / # Electrons / Atomic
Number / Mass
Number / Hyphen Notation / Nuclear
symbol
1. / 23 / 28 / 23 / 23 / 51 / Vanadium-51 /
2. /
3. / 23 / 28 / 20
4. / 47 / 109
5. / 38 / 50
6. /
7. / 35 / 81
8. / 36 / Bromine-79
9. / 22 / 18 / 46
10. / Radium-223
11. / 74 / 108 / 72
12. / 8 / 16
13. / 8 / 9
14. / Oxygen-18
15. /