1. The World of Chemistry

2. The Language of Chemistry
CHEMICAL ELEMENTS -
pure substances that cannot be decomposed by ordinary means to other substances.
Aluminum
Bromine
Sodium

3. The Nature of Matter Gold Mercury
There are 90 naturally occurring elements.

4. Aluminum + Bromine

5. The Language of Chemistry
The elements, their names, and symbols are given on the PERIODIC TABLE
How many elements are there?
116 elements

6. The Periodic Table
Dmitri Mendeleev ( )

7. Glenn Seaborg (1912-1999 ) Discovered 8 new elements.
Only living person for whom an element was named.
Seborgium

8. Copper atoms on silica surface.
An atom is the smallest particle of an element that has the chemical properties of the element.
Copper atoms on silica surface.
Distance across = 1.8 nanometer (1.8 x 10-9 m)

9. The Atom nucleus (of protons and neutrons)
An atom consists of a
nucleus
(of protons and neutrons)
electrons in space about the nucleus.
Electron cloud
Nucleus

10. CHEMICAL COMPOUNDS are composed of atoms and so can be decomposed to those atoms.
The red compound is composed of • nickel (Ni) (silver) • carbon (C) (black) • hydrogen (H) (white) • oxygen (O) (red) • nitrogen (N) (blue)

11. A MOLECULE is the smallest unit of a compound that retains the chemical characteristics of the compound.
Composition of molecules is given by a MOLECULAR FORMULA
H2O
C8H10N4O2 - caffeine

12. Elements form Compounds

13. Graphite — layer structure of carbon atoms reflects physical properties.

14. Kinetic Nature of Matter
Matter consists of atoms and molecules in motion.

15. Physical Properties What are some physical properties? color
melting and boiling point
odor

16. Physical Changes Some physical changes would be boiling of a liquid
melting of a solid
dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION.

17. DENSITY - an important and useful physical property
Aluminum
Platinum
Mercury
13.6 g/cm3
21.5 g/cm3
2.7 g/cm3

18. Relative Densities of the Elements
Density of pure water at 25o C is g/cm3

19. 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 0.95 mm thick. Calculate density (g/cm3).

20. Strategy 1. Get dimensions in common units.
2. Calculate volume in cubic centimeters.
3. Calculate the density.

21. Note only 2 significant figures in the answer!
SOLUTION
1. Get dimensions in common units.
2. Calculate volume in cubic centimeters.
3. Calculate the density.
(9.36 cm)(7.23 cm)(0.095 cm) = 6.4 cm3
Note only 2 significant figures in the answer!

22. Problem:
Liquid nitromethane is used as a fuel for rockets and race cars. It has a density of 1.13 g/cm3. What is the mass, in grams, of 56L of the fuel? Must convert the liters to cm3

23. Answer
M = g

24. DENSITY Density is an INTENSIVE property of matter.
does NOT depend on quantity of matter.
temperature
Contrast with EXTENSIVE
depends on quantity of matter.
mass and volume.
Brick
Styrofoam

25. PROBLEM: Mercury (Hg) has a density of 13. 6 g/cm3
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg in grams? In pounds?
Solve the problem using DIMENSIONAL
ANALYSIS.

26. 1. Use density to calc. mass (g) from volume.
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg?
First, note that 1 cm3 = 1 mL
Strategy
1. Use density to calc. mass (g) from volume.
2. Convert mass (g) to mass (lb)
Need to know conversion factor
= 454 g / 1 lb

27. 2. Convert mass (g) to mass (lb)
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg?
1. Convert volume to mass
( 95 cm3 )(13.6 g/cm3) = 1.3 x 103 g
2. Convert mass (g) to mass (lb)

28. Chemical Properties and Chemical Change
Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules.

29. 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

30. UNITS OF MEASUREMENT Use SI units — based on the metric system Length
Mass
Time
Temperature
Volume
Meter, m
Kilogram, kg
Seconds, s
Kelvins, K
Liter, L

31. Units of Length 1 kilometer (km) = ? meters (m)
1 meter (m) = ? centimeters (cm)
1 centimeter (cm) = ? millimeter (mm)
1 nanometer (nm) = 1.0 x 10-9 meter
O—H distance =
9.58 x m
9.58 x 10-9 cm nm

32. Temperature Scales Fahrenheit Celsius Kelvin Anders Celsius 1701-1744
Lord Kelvin
(William Thomson)

33. 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 degree = 1 degree Celsius

34. Temperature Scales
100 oF
38 oC
311 K oF oC K

35. Calculations Using Temperature
Generally require temp’s in kelvins
T (K) = t (˚C)
Body temp = 37 ˚C = 310 K
Liquid nitrogen = ˚C = 77 K