Element of the Day Fr
Image of light emitted by a sample of 200,000 francium atoms in a magneto­optical trap
Francium (fran­see­әm) is a chemical element with symbol Fr and atomic number 87. It is one of the two least electronegative elements, the other being caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon. As an alkali metal, it has one valence electron.
Bulk francium has never been viewed. Because of the general appearance of the other elements in its periodic table column, it is assumed that francium would appear as a highly reflective metal, if enough could be collected together to be viewed as a bulk solid or liquid. Francium was discovered by Marguerite Perey in France in 1939. It was the last element discovered in nature, rather than by synthesis. Outside the laboratory, francium is extremely rare, with trace amounts found in uranium and thorium ores, where the isotope francium­223 continually forms and decays. As little as 20–30 grams exists at any given time throughout the Earth's crust. Due to its instability and rarity, there are no commercial applications for francium.
Why do you think that it has not yet been possible to view a large sample Francium.
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Chemistry
1. Element of the Day (5)
2. Review Homework
3. Quiz
4. Finish Tanker Problem
Announcements
Due Today: Read pages 378 to 388 and answer questions 65, 67, 70, 75, 79, 84 ­ 86. Due Tuesday: Finish Tanker Problem
Evolution Review: Tuesday May 15th in room 326
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Review Homework
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Notes: Gases
Combined gas law!
WE already know the following relationships
1. PV = k or V =
2. V = bT
3. V = an
These relationships show that volume is dependent upon the following:
where R is the universal gas constant. When the pressure is expressed in atmospheres and the volume is in liters, R has the value 0.08206 L atm/K mol
The ideal gas law is typically written as:
Assumptions that underlie this equation:
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Notes: Gases
A gas exerts pressure on the walls of their container independently of any other gases.
Partial pressure:
Dalton's law of partial pressure:
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Notes: Gases
Example 1
A 5.00 ­ gram sample of helium gas is added to a 5.00 ­ gram sample of neon gas in a 2.50 liter container at 27.0 °C. Calculate the partial pressure of each gas and the total pressure.
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Notes: Gases
Kinetic Molecular Theory of Gases
1. 2. 3. 4. 5. 7
Notes: Gases
Applying stoichiometric calculations to the gas laws.
Example:
Consider the reaction represented by the equation P4(s) + 6H2(g) ­­> 4PH3(g). What volume of hydrogen gas at 27 °C and 1.25 atm is required to react with 5.65 g of phosphorus. 8
Quiz Review
How many torr, mm Hg, and kPa are in 1 atm.
If the pressure of a gas is 5.00 atm with a volume of 20 ­ L, then how many liters would this gas occupy at 2.0 atm?
What is the ideal gas law equation?
Which variables are directly related, inversely related?
What assumptions underlie the ideal gas law?
Write a practice problem with the ideal gas law with your neighbor, then answer.
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Quiz
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Finish Tanker Problem
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Exit Question
There is a direct/indirect relationship between volume and temperature?
Reminders
Due Tuesday: Finish Tanker Problem
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