Homework for 9-17-2010

Galileo Thermometer

Do Now
Please consider this released STAR test question:

Why is cobalt (Co) placed before nickel (Ni) on the periodic table of the elements even though it has a higher average atomic mass than nickel?

1. Nickel has one more proton
2. Cobalt was discovered first.
   
3. Nickel has fewer electrons.
   
4. Cobalt has a lower density.
   

Agenda for 9-17 

1. 1. 1. Do Now
      2. Quickie Quiz discussion
      3. Safety Quiz results 
      4. Homework review 
      5. Homework quiz (open notes)
      6. Head start on weekend homework (time permitting)

1. 
   
   
   

   
   
   
   

   Homework assignment
   pg 96, #58, 59, 62, 65,  66, 70, 72
   

   
   
   
   

   Please do the following problems off of this worksheet:
   
   
   1. Why are numbers used in chemistry often expressed in scientific notation?

   
   

   2. Circle the letter of each sentence that is true about numbers expressed in

   scientific notation.

   • a.   A number expressed in scientific notation is written as the product of a coefficient and a power of 10.
   • b.   The power of 10 is called the exponent.
   • c.   The coefficient is always a number greater than or equal to one and less than ten.
   • d.   For numbers less than one, the exponent is positive.

   
   
   

   3. Circle the letter of the answer in which 503,000,000 is written correctly in

   scientific notation.

   • a. 5.03  10^–7
   • b. 503  10⁶
   • c. 5.03  10⁸
   • d. 503 million

   
   
   

   Accuracy, Precision, and Error (pages 64–65)

   4. Is the following sentence true or false? To decide whether a measurement has

   good precision or poor precision, the measurement must be made more than

   once. ______________________