Problem Solving Lab: Francium Solid, Liquid Or Gas?

Chemistry Problem Solving Lab: Francium – Solid, Liquid or Gas?

Alkali Metals Data Element Melting Point (oC) Boiling Point (oC) Atomic Radius (pm) Lithium 180.5 1347 152 Sodium 97.8 883 186 Potassium 63.7 774 227 Rubidium 38.9 688 248 Cesium 28.5 678 265 Francium ? ? ?

Predicting Of the first 101 elements, francium is the least stable. Its most stable isotope has a half- life of just 22 minutes! Use your knowledge about the properties of other alkali metals to predict some of francium’s properties.

Analysis In the spirit of Dimitri Mendeleev’s prediction of the properties of several, as of then, undiscovered elements, use the given information about the known properties of the alkali metals to devise a method for determining the corresponding property of francium.

Thinking Critically 1. Using the periodic law as a guide, devise an approach that clearly displays the trends for each of the properties given in the table and allows you to extrapolate a value for francium. 2. Predict whether francium is a solid, liquid, or gas at STP (standard temperature and pressure). How can you support your prediction? 3. Which of the given columns of data presents the greatest possible error in making a prediction? Explain. 4. Currently, scientists can produce about one million francium atoms per second. Explain why this is still not enough to make basic measurements such as density or melting point. 5. Concisely define or explain the following terms: francium, isotope, half-life, alkali metals, Dimitri Mendeleev periodic law error, density melting point. Problem Solving Project Rubric Level of Performance Advanced Proficient Basic In Need of Reteaching Criteria (90-100%) (80-89%) (75-79%) (0-74%)

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The student The student The student The student correctly predicts correctly predicts correctly predicts incorrectly predicts whether francium whether francium whether francium whether francium is Prediction of is a solid, liquid or is a solid, liquid or is a solid, liquid or a solid, liquid or atomic properties gas at STP and gas at STP but gas at STP but gas at STP and provides valid provides invalid does not provide does not provide support for his/her support for his/her any support for any support for prediction. prediction. his/her prediction. his/her prediction or provides invalid support.

Response to The student clearly The student The student The student does questions 3, 4, communicates the communicates the communicates the not communicate and 5 understanding of understanding of understanding of the understanding terms and correctly terms and correctly terms and correctly of terms and answers all answers 75% of answers 65-75% of correctly answers < questions. the questions. the questions. 65% of the questions.