1. Chemistry
4/5/2019
Dr Seemal jelani

2. The Language of Chemistry
Pure substances cannot be decomposed by ordinary means to other substances.
Aluminum
Sodium
Bromine
4/5/2019
Dr Seemal jelani

3. The Language of Chemistry
The elements, their names, and symbols are given on the PERIODIC TABLE
How many elements are there?
117 elements have been identified
82 elements occur naturally on Earth
Examples: gold, aluminum, lead, oxygen, carbon
35 elements have been created by scientists
Examples: technetium, americium, seaborgium
4/5/2019
Dr Seemal jelani

4. Measurements in chemistry
4/5/2019
Dr Seemal jelani

5. Types of Observations and Measurements
We make QUALITATIVE observations of reactions — changes in color and physical state.
We also make QUANTITATIVE MEASUREMENTS, which involve numbers.
Use SI units — based on the metric system
4/5/2019
Dr Seemal jelani

6. Metric Prefixes Kilo- means 1000 of that unit
1 kilometer (km) = meters (m)
Centi- means 1/100 of that unit
1 meter (m) = 100 centimeters (cm
Milli- means 1/1000 of that unit
1 Liter (L) = milliliters (mL)
4/5/2019
Dr Seemal jelani

7. Metric Prefixes
4/5/2019
Dr Seemal jelani

8. Units of Length 0.5 kilometer (km) = 500 meters (m)
2.5 meter (m) = centimeters (cm)
1 centimeter (cm) = 100 millimeter (mm)
1 nanometer (nm) = 1.0 x 10-9 meter
O—H distance =
9.4 x m
9.4 x 10-9 cm
0.094 nm
4/5/2019
Dr Seemal jelani

9. Learning Check
Select the unit you would use to measure 1. Your height a) millimeters b) meters c) kilometers 2. Your mass a) milligrams b) grams c) kilograms 3. The distance between two cities a) millimeters b) meters c) kilometers 4. The width of an artery
4/5/2019
Dr Seemal jelani

10. Temperature Scales Fahrenheit Celsius Kelvin Anders Celsius 1701-1744
Lord Kelvin
(William Thomson)
4/5/2019
Dr Seemal jelani

11. Temperature Scales Fahrenheit Celsius Kelvin 32 ˚F 212 ˚F 180˚F 100 ˚C
Boiling point of water
32 ˚F
212 ˚F
180˚F
100 ˚C
0 ˚C
100˚C
373 K
273 K
100 K
Freezing point of water
Notice that 1 kelvin = 1 degree Celsius
4/5/2019
Dr Seemal jelani

12. Calculations Using Temperature
Generally require temp’s in kelvins
T (K) = t (˚C)
Body temp = 37 ˚C = 310 K
Liquid nitrogen = ˚C = 77 K
4/5/2019
Dr Seemal jelani

13. Always estimate ONE place past the smallest mark!
4/5/2019
Dr Seemal jelani

14. TEMPERATURE
4/5/2019
Dr Seemal jelani

15. SCALES
Kelvin
Fahrenheit
Celsius
4/5/2019
Dr Seemal jelani

16. To Celsius To Kelvin To Fahrenheit Conversions 4/5/2019
Dr Seemal jelani

17. °C  x  9/ = °F
(°F  -  32)  x  5/9 = °C
4/5/2019
Dr Seemal jelani

18. Examples 1) Convert 37°C to Fahrenheit. 37°C x 9/5 + 32 = 98.6°F
4/5/2019
Dr Seemal jelani

19. Convert 98.6°F to Celsius. (98.6°F - 32) x 5/9 = 37°C
4/5/2019
Dr Seemal jelani

20. DENSITY - an important and useful physical property
Aluminum
Platinum
Mercury
13.6 g/cm3
21.5 g/cm3
2.7 g/cm3
4/5/2019
Dr Seemal jelani

21. Density often has units of grams per cubic centimeter (g/cm3).
Remember, grams is a mass and cubic centimeters is a volume (the same volume as 1 milliliter).
4/5/2019
Dr Seemal jelani

22. Density is a fundamental concept in the sciences
It is used quite often in identifying rocks and minerals since the density of substances rarely changes significantly
For example, gold will always have a density of g/cm3; if a mineral has a density other than that, it isn't gold.
4/5/2019
Dr Seemal jelani

23. How do I determine density?
A concrete cube will weigh more than a cube of air the same size because it is denser
Density is not something that is directly measured. Typically if you want to know the density of something you will weigh it and then measure its volume.
4/5/2019
Dr Seemal jelani

24. Another tricky thing about density is that you can't add densities
If I have a rock that is made up of two minerals, one with a density of 2.8 g/cm3, and one with a density of 3.5 g/cm3, the rock will have a density between 3.5 and 2.8 g/cm3, not a density of 6.3 g/cm3
This is because both the mass and the volume of the two minerals will be added, and so when they are divided to get the density the result will be between the two.
4/5/2019
Dr Seemal jelani

25. Typical densities for gasses are on the order of thousandths of grams per cubic centimeter
Liquids often have densities of about 1.0 g/cm3, and indeed, fresh water has a density of 1.0 g/cm3
Rocks often have a density around 3 g/cm3, and metals often have densities above 6 or 7 g/cm3.
4/5/2019
Dr Seemal jelani

26. Problem A piece of copper has a mass of 57. 54 g. It is 9
Problem A piece of copper has a mass of g. It is 9.36 cm long, 7.23 cm wide, and mm thick. Calculate density (g/cm3).
4/5/2019
Dr Seemal jelani

27. Solution
2) Placing the mass and volume of the osmium metal into the density setup, we obtain D = mass = g = volume 2.22 cm3 = g/cm3 = 22.5 g/cm3
4/5/2019
Dr Seemal jelani

28. Scientific Method State the problem clearly. Gather information.
Form a hypothesis..
Test the hypothesis.
Evaluate the data to form a conclusion.
If the conclusion is valid, then it becomes a theory. If the theory is found to be true over along period of time (usually 20+ years) with no counter examples, it may be considered a law.
6. Share the results.
4/5/2019
Dr Seemal jelani