Question of the Day Rules You must work alone You may use your periodic table today You have 6 minutes to complete the QOD Good luck!!

Stoichiometry Question Oxygen gas can be produced by decomposing potassium chlorate using the reaction below. If g of KClO 3 is heated and decomposes completely, what mass of oxygen gas is produced? KClO 3 (s) --> KCl (s) + O 2 (g)

1. Balance your equation first. 2KClO 3 (s) --> 2KCl (s) + 3O 2 (g) 3 mol O 2 2 mol KClO 3 x g KClO g O 2 = 32.0 g O 2 1 mol O 2 x 1 mol KClO g KClO 3 x

What are we doing Today? Nuclear Transformations Ch. 4 (EST) Hand in Lab (Endo & Exo) QOD Nuclear Transformations (EST) Practice Problems

Nuclear Transformations p

Radioactivity Radioactivity: Is a natural process in which an unstable atom spontaneously transforms into a more stable atom, or several more stable atoms, while releasing energy in the form of radiation (p.126)

Nuclear Stability (p.125) Nuclear Stability is a concept that helps to identify the stability of an isotope. Stability: you need to find the ratio of neutrons to protons. (Look at table 4.25 on page 125)

An unstable or radioactive substance may emit three types of radiation, referred to as ionizing radiation.

Gamma rays Is only made up of energy, not particles. They are neutral. They can easily penetrate through materials. So you need a very dense material. (Lead) The * in the reaction denotes an excited nuclear state.

Alpha Particles. Are positive particles Large and Heavy, so can be stopped by a piece of paper. Example: The daughter nucleus has an atomic number 2 less and an atomic mass 4 less than the parent nucleus.

Beta Particles. Are negative particles Lighter then alpha particles and penetrate further The daughter nucleus has an atomic number 1 more and an atomic mass the same as the parent nucleus. Example: Later we will find there is something missing from this reaction.

Here's a plot of the activity of a radionuclide. The initial activity was chosen to be 1000 for this plot. The half-life is 10 (in whatever time units we are using). All decay curves look like this; only the numbers on the axes will differ, depending on the radionuclide (which determines the half-life) and the amount of radioactive material (which determines the initial activity).

Example: radon (nasty stuff) has a half-life of 3.8 days. If you start with 1 mg of radon, after 3.8 days you will have 0.5 mg of radon. Days Radon Left (mg)

FUSION AND FISSION

Fusion Reactions 2 small nuclei release energy when they are fused together to form a single, larger nucleus The process releases energy Energy must be supplied to create bigger nuclei

THE SUN Every second, the sun converts 500 million metric tons of hydrogen to helium. Due to the process of fusion, 5 million metric tons of excess material is converted into energy in each second. This means that every year, 157,680,000,000,000 metric tons are converted into energy.

Nuclear Fission Energy is released in a nuclear reactor as a result of nuclear fission Fission is another word for splitting. The nucleus of an atom of a fissionable substance splits into two smaller ‘fragment’ nuclei This event can cause other fissionable nuclei to split, leading to a chain reaction of fission events Two isotopes in common use as nuclear fuels are uranium-235 and plutonium-239

Chain The additional neutrons released may also hit other uranium or plutonium nuclei and cause them to split – even more neutrons are then released, which in turn can split more nuclei. Called a chain reaction

Chain Reaction Krypton Barium n n n n Uranium More decays

Chain Reaction

Chapter 4 EST Test Chapter 4 EST Test on Wednesday, Dec 17 Tutorial will be on Monday, Dec. 15 at 3:15pm

That was the end of Chapter 4 (EST) Class Work 1)In your textbook p.134 Questions: 20, 21, 22, 23 2)In your textbook p.134 Questions: 24, 25, 26, 27, 28 25