How does the Sun give off Energy What

How does the Sun give off Energy?

What does the term “Nuclear reaction” make you think of? • The Nucleus of the Atom!! • What do you think reacts in a Nuclear Reaction? • Protons and Neutrons! • What reacts in a combustion reaction or other typical chemical reactions? • Electrons! • Which will generate MORE Energy: NUCLEAR REACTIONS!!!

Protons and are attracted As getneutrons heavier, they become more In aelements stable nucleus, the attraction due Nuclear “reactions” DO form new unstable. Extra neutrons must be present in to the strong force is greater than the to each other by the strong nuclear elements which makes them Nuclear changes occur when nucleus the nucleus (like glue) to increaseastability repulsion due to electrostatic force. DIFFERENT from chemicalreactions becomes unstable. by increasing the strong force.

WHAT MAKES NUCLEAR CHANGES DIFFERENT FROM CHEMICAL CHANGES? Some nuclei can become unstable by artificial Nuclear reactions can produce enormous Examples of naturally occurring nuclear Nuclear reactions change the protons transmutation, where a nucleus is bombarded (or amounts of energy as nuclear mass is reactions include alpha and beta decay, of an atom’s nucleus –the element will shot) with a particle that creates instability and 2)!!! converted into energy (E=mc and fission and decay. fusion. causes radioactive change!!

THINK ABOUT THE WORDS FUSION & FISSION When you FUSE two objects, what do you do? Join them together! How about the word Fission? To break apart. Talk with your neighbor- what is the difference between Nuclear Fusion and Nuclear Fission? ?

Example of Nuclear Fission nuclear fission 235 U 92 + 10 n→ 9038 Sr + 14354 Xe + 310 n

Example of Nuclear Fusion nuclear fusion 2 H 1 + 31 H→ 42 He + 10 n

COMPARE the 2 types of Nuclear Reactions! 2 H 1 + 31 H→ 42 He + 10 n nuclear fusion nuclear fission 235 U 92 + 10 n→ 9038 Sr + 14354 Xe + 310 n

Nuclear Fusion and Fission Lighter nuclei undergo fusion to become more stable …. and heavier nuclei become more stable by fission.

NUCLEAR FUSION: §Process of combining 2 lighter and smaller Nuclei into 1 Heavier Nucleus §This CHANGES the element and forms a new type of atom. §An ENORMOUS amount of ENERGY is releaed in the process

WHERE DOES NUCLEAR FUSION OCCUR? §In the Cores of STARS (Like our SUN!!) under EXTREME conditions of VERY high temperature and pressure. §As you read in the article, the FUSION of 2 Hydrogen nuclei forms a Helium nucleus in the sun: 2 H + 1 H 3 He 1 1 2 How does this process release a LOT of energy?

FUSION AND E = 2 MC Einstein’s famous equation E = mc 2 (mass times the speed of light squared) shows us that matter can be converted into energy. This releases vast amounts of energy from a very small amount of matter. Think about C 2 … its large (remember: C=3. 0 x 108 m/s) Fusion is not a chemical reaction it IS a nuclear reaction…

NUCLEAR REACTIONS https: //www. youtube. com/watch? v=-22 tna 7 KHz. I

COMPARE AND CONTRAST… H 2 + O 2 H 2 O this is a chemical equation H + H + H He this is a nuclear equation… So what is the big difference?

WHAT CAUSES FUSION IN STARS OR THE SUN? Stars (like our sun) are formed when a very large cloud of gas condenses under gravity. The mass involved is enormous which means the force of gravity also very large. This causes intense pressures in the center of the cloud and results in very high temperatures. Once fusion begins the star’s life is regulated by the balance between gravity pulling in and the explosive energy of fusion pushing out.

WHERE DOES THE ENERGY THAT’S RELEASED COME FROM? A CHANGE IN MASS THAT IS CONVERTED TO ENERGY!!

TWO HYDROGEN-1 NUCLEI COMBINE TO PRODUCE A HYDROGEN-2 NUCLEUS…. Describe what happens in the AND THEN… second and third nuclear equations. How are nuclear equations fundamentally different from chemical

RADIOACTIVE DECAY EQUATIONS (HOW TO UNDERSTAND THEM) Alpha decay equation (lose 2 p, 2 n): Beta decayisotope equation “daughter” (n→p+e-): “parent” isotope