Before Bell Rings Chill out

ETD #12 Define Nucleosynthesis What subatomic particles (proton, neutron, electron) are represented by the following symbols: 0-1X 11Y 10Z

ETD #12 Define Nucleosynthesis The creation of new nuclei through preexisting protons and neutrons. What subatomic particles (proton, neutron, electron) are represented by the following symbols: 0-1X electron 11Y proton 10Z neutron Nucleosynthesis can be remembered by breaking it apart. The nucle- in the beginning sounds like nucleus, so we know it will involve the nucleus. Synthesis just means to combine things, so if we put the two together, it means making nuclei. We know that a beta particle is just an electron, so if we know that a beta particle is 0-1e-, we will know when we see 0-1, it will be an electron. Also remember that the top number is the mass of the particle and the only one out of proton, neutron, and electron to not have a mass is an electron. To know that 11Y is a proton we have to look at the numbers next to the symbol. The bottom number is the atomic number of the entity, so this symbol shows an atomic number of 1. Since atomic number is the same as number of protons, this means 11Y has one proton. Since it has one proton, I has to be the proton. To know that 10Z is the neutron, we have to look at the numbers next to the symbol as well. The top number is the mass, the bottom the number of protons/atomic number. Since the bottom number is zero, this entity cannot have any protons. The mass is one, so it must be a particle without protons that has a mass of one. The only particle that fits these requirements is the neutron, since it has a mass of 1 and no protons.

Learning Targets I can describe what elements it is possible for a given star to make. I can describe the core composition of a star.

Test Corrections Come in this week to do test corrections.

Grade the Quiz Out of 10 points, 1 point for each blank Have to have the correct numbers and element If they wrote alpha or beta as just the symbols, that is ok.

Low Density Shell High Density Highest Density Notice the lowest density (lowest atomic number) element is in the outer shell. As we move closer to the core, the elements get more dense with the most dense (highest atomic number) element at the core of the star. In a low mass star like the sun, the yellow shell would contain excited hydrogen, the red shell the hydrogen fusing to form helium, and the core would be where the helium fuses into carbon. The sun is not currently fusing helium into carbon, since it still has large amounts of hydrogen to fuse into helium.

Different phases of stars all happen due to the balance between gravity pulling the star towards the core and the pressure out generated by the energy coming from the fusion reactions. When the fusion reactions slow down, such as when most of the hydrogen in a star is used up, there is less pressure out so the star starts to collapse. This creates greater pressure and heat in the core until eventually helium starts to fuse into carbon. This releases energy, causing the star to expand. Since helium fusion generates more energy than hydrogen fusion, the star expands larger than when it was only doing hydrogen fusion, becoming a red giant star. When the sun becomes a red giant, it will be so large it will swallow Mercury, Venus, and maybe even Earth.

Low Mass Star Excited Hydrogen H Fusion in core 4 H  He These are the different levels in a low mass star in its main sequence. The excited hydrogen is fused into helium in the core, releasing energy. It requires 4 hydrogen atoms to make one helium atom.

Red Giant: 4 Layered Core Non-fusing H Shell Excited H H fusing He fusing C Core Core When a low mass star runs low on hydrogen to fuse, it collapses until the core becomes hot enough and has enough pressure to fuse the helium. Three helium atoms fuse to form a carbon atom. Again notice how the denser element is in the core and the layers get less dense as you move out from the core.

High Mass Star Excited Hydrogen If a star is massive enough, it will start the fuse carbon to make elements that have a higher atomic number. The largest element that can be made in stars is iron (Fe). This is because the fusion reaction to make iron in a star actually takes in more energy than it releases, so once a star starts to fuse iron, it will eventually run out of the energy required to perform fusion. Once this happens, the star collapses, getting hotter and increasing core pressure. Eventually this heat and pressure causes atoms to break down into protons, neutrons, and electrons. The collapse continues until the outer layers eventually hit the super dense core of the star. They then bounce back from the core in a giant explosion called a supernova. During a supernova, massive amounts of energy is released and a flurry of fusion reactions take place in this super hot, super dense core. This is where elements larger than iron come from. If the star is massive but not super massive, it will then turn into a neutron star. If the star is massive enough, the collapse will result in the formation of a black hole, an area with such a strong gravitational pull that even light cannot escape.

Basic lifecycle of a stars Basic lifecycle of a stars. The sun is an average mass star, so it will follow the top path.

What Stars Make What Low Mass Stars like the Sun can make up to carbon He and C High Mass Stars can make up to iron (Fe) He, C, and Fe Supernovas needed for anything larger than iron (Fe) He, C, Fe, and anything larger than Fe This is important. Just a list of what elements each type of star can create. Low mass stars can make up to carbon. High mass stars can make elements up to iron. A supernova is required to make elements with a higher atomic number than iron.

Review/HW time Rest of the period to work on the review WS and nucleosynthesis WS Nucleosynthesis WS due next class, review WS is not going to be turned in, it is just to help you review. You don’t have to color in the last page of the Nucleosynthesis WS, just label the layers.

Learning Targets I can describe what elements it is possible for a given star to make. I can describe the core composition of a star.

Homework Nucleosynthesis WS Study for test- Next class