ONCE YOU ARE IN THE DOOR, YOUR IN. 1. NO Questions will be answered until 5 minutes after the bell. (remember parking lot for unanswered questions). 2.Put all electronic devices away by the time the tardy bell rings. If I see it after the bell I will take it. ALL FOOD MUST BE AWAY BY THE TIME TO BELL RINGS. 3. TURN IN YOUR ClEvR Summary .TURN IN YOUR ANTICIPATION GUIDE IF YOU HAVEN’T ALREADY. Pick up daily handouts. PICK UP PASSED BACK PAPERS IN YOUR FOLDER IN THE BLACK FILE BOX. Check no-name folder. Move to Assigned seat. Start your Do Now in the Do Now form. _____________________________________________________________ DO NOW (9/13/2013) DO NOW: How many grams are in 2.5 mol of Mg? What is the formula mass of MnH4?   How many grams are in 1 mol of MnH4?

Exit Ticket (9/12/2013) What is Avogadro’s Constant? How many moles are in 25.0 grams of water (H2O)? ** See Mole Calculation Worksheet

PROCEDURES WHY?????????? Once you are in, you are in Tardy Bell = Electronics away, voices at ZERO NO Questions until 5 minutes after the bell NO Questions unrelated to content until Independent/Group work at the end (parking lot) DO NOT GET OUT OF YOUR SEAT WITHOUT PERMISSION (hole punch, tissues, trash) RAISE YOUR HAND TO SPEAK Bathroom (5) Pick up turned back papers when you pick up daily handouts Check the no-name folder at the back DATE on the Do Now form (1/2 point ) 3,2,1 – Eyes on me ABSENT? Make Up Quizzes / Tests WHY??????????

Homework Finish M&M lab questions Finish M&M lab report *** *** graded

Tutoring Today after school 2:30-3:30pm in 529 with Mrs.Murphy Thursday after school 2:30-3:30 in 710 with Ms.Wheeler and Mrs.Elam-Rice

Unit 2: Nuclear Chemistry Day 6 – Fusion, Fission, and Half-Life

Nuclear Decay Per Table Group: (move those who need partner) One person does even, One does Odd. http://www.youtube.com/watch?v=cOE40P5rHCA&list=HL1378937680 Compare with your partner – make sure you have all the answers to the guide If you are missing some the EVEN person can be a spy

Types of Nuclear Reactions Fission: big atoms break up to form smaller atoms. Often more particles are also emitted. Gives off huge amounts of energy (exothermic) Chain reactions usually occur: when the pieces “break away”, they hit new atoms & break those apart. Common in nuclear power plants & weaponry n + U-235  Te-137 + Zr-97 + 2 n or n + U-235  Ba-142 + Kr-91 + 3 n

Types of Nuclear Reactions Fusion: small atoms combine to make big atoms Requires huge amounts of energy. What happens in stars (i.e. our sun) Most common fusion reactions occur in stars. H + H  H-2 + b+ H + H-2  He-3 He-3 + He-3  He-4 + 2 H He-3 + H  He-4 + b+

Half-Life The amount of time it takes for an isotope to have half of the original amount. Every radioactive isotope has it’s own half-life In order to figure out how many half lives have occurred, how long it takes for a sample to decay, the percentage remaining, the amount remaining, etc, do the following…… Write down what you start with (i.e. the original amount at time = 0 (time = 0 means no decay has occurred) After one half-life, there will be half as much (i.e. grams) as the original sample. Continue to do this until you have reached your desired amount. It is not possible to reach 0 grams – the amount just gets so small, we quit counting.

Original amount in sample: Example 1 The half life of Radium – 226 is 1600 years. If there are 20 grams of the sample present initially, how much exists at the end of 4 half lives? Original amount in sample: 20 g 10 g 5 g 2.5 g 1.75 g Half Life of Ra-226 = 1600 yrs Today 1600 years from now 3200 years from now 4800 years from now 6400 years from now

Example 2 The half-life of radium-222 is 38 seconds. How many grams of radium-222 remain in a 12-gram sample after 76 seconds? After 114 seconds? (76s) 3grams (114s) 1.5

Practice 1 If gallium-68 has a half-life of 68.3 minutes, how much of a 10.0 mg sample is left after one half life? Two Half-lives? Three half-lives? 1) 5mg (2) 2.5mg (3) 1.25mg

Practice 2 If the passing of 5 half-lives leaves 25.0 mg of strontium-90 sample, how much was present in the beginning? (0) 800mg Sr-90

Half-Life (graph practice) What is the half-life of carbon-14? How do you know? What percentage of carbon-14 remains after 17,190 years? Predict what percentage of the original carbon-14 sample will remain after 28,650 years. True or false: Elements with stable nuclei are radioactive

Exit Ticket (9/13/2013) Alpha decay refers to – Half-life defined in your own words ** See Mole Calculation Worksheet