chemistry-chapter1

3 is written: 3×100 24 is written: 2.4×101 346 is written: 3.46×102 2537 is written: 2.537×103
0.2 is written: 2×10-1 0.046 is written: 4.6×10-2 0.365 is written: 3.65×10-1 0.00753 is written: 7.53×10-3
Example 1.1 Using metric system prefixes Express (a) 0.005 second (s) in milliseconds (ms); (b) 0.02 meter (m) in centimeter (cm); (c) 0.007liter (L) in milliliters (mL).
Pure Substances have unique and consistent physical and chemical properties. There are only two kinds of pure substances: elements and compounds. Mixtures consisted of two or more pure substances in varying proportions. * Mixtures have properties that are variable and depend on the proportions of the components. * A mixture is either heterogeneous or homogenous.
five significant figures 2.1600×104 three significant figures 2.16×104
Figure 1.5 The element lithium is less dense than water or oil, and oil is less dense than water. The oil floats on water, and lithium floats on the oil.
Molecular recognition Biological and chemical systems distinguish between molecules and regulate behavior accordingly
Reaching equilibrium Biological and chemical processes are dynamic and reversible and the outcome can be manipulated depending on condition Engine of life The energy currency (or coin) of living organism is the making and breaking of bonds
The unavoidable estimate in measurement is called the uncertainty or variability.
The difference between the true value and the measured value.
It indicates the uncertainty by means of the number of digits instead of ± notation. * A trailing zero, as in 4.130 is significant. * A zero within a number, as in 35.06cm, is significant. * A zero before a digit, as in 0.082, is not significant. * A number ending in zero with no decimal point, as in 20, is ambiguous. Ambiguities of this last type can be prevented by the use of scientific or exponential notation.
Figure 1.6 The substance nitric oxide (NO2) can exist in three states, (a) gas, (b) liquid, and (c) solid, and can be reversibly transformed from one state into another without losing its chemical identity.
Course material
• Textbook: Available from the school’s publishing agency Scientific Calculator • Characteristic of medical General chemistry
• Method of study
Energy from the Sun Absorption of light causes the rearrangement of electrons, which in turn causes the growth of living organisms
1.1 The composition of matter
Solution
0.001s 1ms 0.01m 1cm
0.001L 1mL
therefore
therefore
0.005s 5ms
0.02m 2cm
0.007L 7mL
therefore
1.3 Measurement，Uncertainty and Significant Figures
Prof. Qingbing Zeng
The Language of Chemistry
Chemistry in Your Future You arrive for your shift at the skilled nursing facility and read on a patient’s chart that the doctor has prescribed a 100-mg dose of Colace. The pharmacy sends up a bottle of the medication in syrup form, containing 20 mg of medicine in each 5 mL of syrup. How many milliliters of the syrup do you give to your patient? A simple calculating technique that you learned in Chemistry helps you find the answer.
Figure 1.4
Thin-layer chromatography can separate complex mixtures and allow the identification of each compound.
1.2 Measurement and The Metric System
Figure 1.3 A distillation apparatus. If two liquids are to be separated, the liquid with the lower boiling temperature will vaporize at a lower temperature and leave the distillation flask before the higher-boiling liquid. The vaporized liquid leaves the flask and enters the condenser, a long glass tube with a glass jacket surrounding it through which cold water is circulated. There the cooled vapor condenses to a liquid and is collected in the receiving flask. A solution of a solid also can be separated by this technique, in which case the solid remains in the distillation flask.
Figure 1.9 Clockwise from left : the red-brown liquid bromine, the silvery liquid mercury, and the solids iodine, cadmium, red phosphorus, and copper.
Figure 1.8
Chemical compounds found in the kitchen.
Figure 1.2 Filtration is used to separate liquids from solids. The filter paper retains the solid because the particles of the solid are too large to pass through the pores, or openings, in the paper. Micropore filters, which have pore sizes small enough to retain bacteria, are used to produce sterile water, sterile pharmaceutical preparations, and bacteria-free bottled beer.