Introduction to chemistry: Chapters 1, 2 and 3

 

 

 

  1. What is chemistry?  Study of composition of matter.
  2. What are the five major areas (and their definitions) of chemistry?

1)      Organic chemistry:  Study of all matter containing carbon. 

2)      Inorganic chemistry:  Study of matter not containing carbon (usually non-living things).

3)      Analytical Chemistry:  Study of the composition of substances.

4)      Physical Chemistry:  Theories and experiments regarding the behavior of chemicals.

5)      Biochemistry:  Study of chemistry in living organisms.

 

 

 

  1. Explain the difference between pure and applied chemistry?  In applied chemistry, scientists apply knowledge to achieve certain goals (like developing new technologies).  In pure chemistry, scientists gather knowledge for its own sake. 
  2. What is the composition of plastic? Plastics are also called polymers and they are made up gigantic molecules.
  3. What are the four major steps of the scientific method?  Identify the problem; write a purpose, experiment and conclude (if you want to go into more detail; the experiment part includes collection of data; graphing/organizing of data and the analysis of data). 
  4. What is an observation? Using your sensing to directly obtain information.
  5. What are the different types of observations? Quantitative observations and qualitative observations.
  6. What is a quantitative observation? It examines properties of substances that are numerical (the properties are numerical not the substances)
  7. What is a qualitative observation? It examines properties of substances that are not numerical (for example: color, odor, texture etc.)

MATTER AND CHANGE - Assembled by Mahima Kishore

1. What is matter? Anything that takes up space and mass.

2. What is mass? The amount of matter it contains (that’s a bad definition)…it’s the amount of "stuffing" in an object.

3. What is a substance? Only contain one kind of matter (sometimes known as pure substances). All samples of the same substances have the same physical properties.

4. What is physical property? Quality or condition of a substance that can be observed or measured without changing the substance’s composition. Ex: color, solubility, odor, hardness, density, melting point, and boiling point.

5. What is a solid? Matter with a tangible shape and volume. (Cannot be shrunken into a smaller volume or shape…they only expand when slightly heated "incompressible")

6. **Physical state of a substance is also a physical form***

7. What is a liquid? Type of matter that flows, has a fixed volume and takes the shape of whichever container it is. They tend to expand (more than solids) when heated so they are almost incompressible.

8. What is a gas? It flows to take the shape and VOLUME of its container. Particles are really quite apart.

9. What is vapor? It is the gaseous form of a substance that is usually liquid.

10. What is a physical change? Altering a material without changing its chemical composition.

11. What is a mixture? Physical blend of two or more pure substances. Their compositions may vary

12. What is a homogeneous mixture? Homogeneous mixtures have the same composition in any given part of the sample. Homogeneous mixtures have definite composition and properties.

 

13. What is a heterogeneous mixture? ? It is a mixture that has no definite composition.  Heterogeneous mixtures are not even all throughout.  They are said to have phases which are parts of homogeneous compositions that can be mechanically separated from the overall heterogeneous mixture.  

 

14. What’s a phase? A part of a mixture that has uniform composition.

15. What is distillation? Boil a liquid, then condense it…. by doing this you can separate the components in a mixture (like distilled water)

16. What are the two categories in which substances can be divided? Elements and Compounds.

17. What are elements? Simplest form of matter that exist under normal lab conditions. They are building blocks for all other substances.

18. What are compounds? Two or more elements chemically bonded together. They can be separated into simpler matter only by chemical means. Properties of compounds much different from those of the elements that compose it.

19. What are the two groups in which pure substances can be classified? Elements and Compounds.

20. What are elements? They are simplest form of matter that can exist under lab conditions. They cannot be separated into simpler forms by chemical means. They are building blocks for all other substances.

21. What are compounds? Two or more elements chemically bond to form compounds. These are substances that can only be separated by chemical means.

22. Properties of compounds are very different from their components; true or false? True.

23. What is a chemical symbol? One or two letters that represent each element.

24. What is a chemical reaction? When one or more substances form to make a new substance.

25. What are reactants? The starting substances in a reaction

26. What is a product? The result of a chemical reaction.

27. What is a chemical property? The ability of a substance to undergo chemical change and to produce new substances. Chemical properties are only observed when a substance undergoes chemical change.

28. What are the indicators that a chemical reaction has taken place? They are: change in color, heat, generation of a gas and the change on the surface of a solid.

29. What is the law of Conservation of Mass? It says that during physical or chemical changes, mass is not created or destroyed; it is conserved.

30. What is a solution? It is a type of homogeneous mixture. It consists of one or more substances, which are the solutes, dissolved in another substance called the solvent.  Solvents are usually water but they don’t have to be. A common polar solvent is water.

Scientific Measurement :  Assembled by Mahima Kishore

1. What are qualitative measurements? They give results in a descriptive non-numerical form.

2. What are quantitative measurements? They give results in a numerical forms.

3. What is scientific notation? Short for a writing a number that is incredibly small or very large. It is written as a coefficient times ten raised to a power. For example 3500 would be 3.5 X 103

4. Define Accuracy? How close the measurement is the actual or accepted value.

5. Define precision? How close the measurements are to each other.

6. What is accepted value? It is the correct value, derived from reliable resources.

7. What is experimental value? Value measured in the lab.

8. What is the percent error? The absolute value of the quantity accepted value minus experimental value, over the accepted value, all which multiplied by 100.

( |Value accepted – Value measured | )

                        -----------------------------------------------  X 100 = percentage error

Value accepted

 

9. What are significant figures? The significant figures in a measurement include all the places that are known and the last place, which is estimated (also known as the uncertainty).

10. What are the rules of determining whether a number is significant? 1. All non-zero numbers are significant. 2. Zeros appearing between non-zero digits are significant. Left most zeros before non zero digits are not significant. 3. Zeros at the end of a number and to after a decimal point are always significant.

11. What are the rules for rounding in addition/subtraction? Adding and subtracting with precision:  When doing calculations involving measurements, the answer can only be as accurate as the LEAST accurate measurement made.  The answer must be rounded off to the same column as the LEAST precise measurement used in the calculation.  For Example:  246.58 – 87.3 = calculated answer: 159.28, rounded to the correct precision: 159.

 

12. What is the formula for density? Density equals the mass over volume.

13. What is specific gravity? Ratio/comparison of the density of a substance to the density of a reference substance (usually water) of the same temperature.

14. What is the temperature of an object? The temperature of an object determines the direction of heat transfer.

15. ***Make sure you know the basic metric untis: meters (for length), kilometers (for weight), liters (for volume) and their divisions.

16. Multiplying and dividing in significant figures: The answer must be rounded off to the same number of significant figures as the least accurate measurement used in the calculation (the number with the least number of significant figures). For example: multiply 34.0 and .0921084.  The first number as 3 sig figs and the second one has 6. Calculator answer:  3.1316856 . Rounded to correct accuracy (three significant figures) 3.13

17. Significant figures with scientific notation: Count significant figures only for the first part of the notation.

18. What are some important rules of scientific notation:   a) Scientific notations is a rational number times ten raised to a power.  b) That rational number must be greater than zero and less than 10.  c) The power of ten indicates how many places the decimal point has been moved. d) If the original number is large (greater than one) then the exponent is positive and the original number is small  (less than one) then the exponent is negative.

 

19. How do you multiply in scientific notation? Multiply the first part as usual and ADD the exponents.  SAMPLE PROBLEM:  (2 X 104) times (3X 105):  Multiply three and two as usual and add the powers of ten:  6 X 109 

 

20. How do you divide in scientific notation? Divide the first part as usual and SUBTRACT the exponents.            SAMPLE PROBLEM:  (6 X 109) divided by (3 X 10 5). Divide six by three as usual and subtract the powers of then. 2 X 104

 

21. Some examples of scientific notations:

 

Regular Form

Scientific Notation

3,500,000

3.5 X 10­­6

400

4 X 102

.000062

6.2 X 10-5

.007419

7.419 X 10-3