Friday, May 27

We started off the class with Mr. H telling us a story about how his wife gave him a salad in a bowl giving off radiation. He then proceeded to show us by using this device [I don't know what it's called...] and pointing it at the bowl. Basically, it beeps when it detects it. He pointed it at everyone in the class and the people who were giving off a lot of radiation were Matt, Dmitry, Kevin, and Emma. Mr. H told Emma to make her own Chemistry blog because of the great blog she posted the day before. If you need a good resource, look at Emma's blog.

He then talked about how finals were in 7 days. There is going to be a review day the Tuesday before finals start.

We turned to page 1 to start off the lesson of the day. Mr. H explained to us that radiation is everywhere. Even though when the news talks about radioactive substances, it's not going to be deadly because those amounts wouldn't kill you. He gave us examples like the sun giving off radiation, but the atmosphere absorbs much of them so we aren't harmed by it. He also told us a story about a guy who took a radiation detector on his trip to Hong Kong, Japan, and back to the US and the data showed that the places the radiation detector went nuts on was when he was in the airplane. We can conclude that we are safer on the ground than in the air.

So, page 1, numbers 1, 2 and 3 were all review questions from Unit 2.

Atomic number: number of protons, identifying number

Mass number: number of protons and neutrons

Isotope: form of an atom of an element

Nuclide: nucleus of an atom

2. El is the symbol for the element

A is the mass number

Z is the atomic number or the number of protons.

This was all review so I'm not going to go over it but the answers are as follows for number 3.

Lithium-7: 3, 7, 3, 4

Carbon-14: 6, 14, 6, 8

Lead-210: 82, 210, 82, 138

Uranium-238: 92, 238, 92, 146

#4. a. 1 b. 1.5 c. 83

For number 4, you are supposed to use the chart on the right. The explanation for letter a is that when the proton count is lower(<20), there is a 1:1 ratio between the protons and the neutrons. When the proton count is higher(>20, the neutron count also gets higher. The ratio is about 1:1.5. Then, when the atomic number is at 83 or higher, the element is considered radioactive. In the chart, the elements that are not radioactive are represented by dots. When it is radio active, there are no more dots.

We turned to page 2 and worked on number 6 for the end of the class. Mr. H explained the different types of radioactive decay. Beta decay are high speed electrons and don't get through the skin. Alpha decay also doesn't get through the skin and has a helium nucleus. Positron emission is an anti electron and gamma decay is a high energy light particle. The answers go as follows:

a. beta

b. alpha

c. positron

d. positron

e. gamma

f. alpha

g. gamma

h. beta, alpha

i. alpha

j. electron capture, beta

k. gamma, alpha

l. gamma

We ended the class with that page. Have a great three-day weekend!