Introduction to Physical Science Monday Wednesday Thursday Tom

Introduction to Physical Science Monday, Wednesday, Thursday Tom Burbine tomburbine@astro. umass. edu

• Fission – Splitting of the nucleus of a heavy atom with the release of energy • Fusion – Combination of the nuclei of light atoms to form heavier nuclei with the release of energy

Energy Source for Sun • Fusing hydrogen into helium – Hydrogen nucleus – 1 proton – Helium nucleus – 2 protons, 2 neutrons • Need high temperatures for this to occur • ~10 to 14 million degrees Kelvin

http: //www. astronomynotes. com/starsun/s 3. htm

http: //www. astronomynotes. com/starsun/s 3. htm

How does Fusion Convert Mass to Energy • What is the most famous formula in the world?

E = mc 2 • • m is mass in kilograms c is speed of light in meters/s E (energy) is in joules very small amounts of mass may be converted into a very large amount of energy

Who came up with it?

http: //msnbcmedia 3. msn. com/j/msnbc/Components/Photos/z_Projects_in_progress/050418_Einstein/050405_einstein_tongue. widec. jpg

Law • Law of Conservation of mass and energy – Sum of all mass and energy (converted into the same units) must always remain constant during any physical process

Reaction • 4 protons → helium-4 + 2 neutrinos + energy Neutrino-virtually massless, chargeless particles Positron-positively charged electron – annihilated immediately by colliding with an electron to produce energy

Antiparticles • Antiparticle – particle with the same mass and opposite electric charge • Antiparticles make up antimatter • Annihilation – when a particle and an antiparticle collide • Antimatter is said to be the most costly substance in existence, with an estimated cost of $62. 5 trillion per milligram.

Fusion reaction • Much more complicated than 4 protons → helium-4 + 2 neutrinos + energy

Deuteron – Deuterium (hydrogen with a neutron) nucelus

Proton-Proton Chain Reaction • This reaction occurs ~1038 times each second • It if occurred faster, Sun would run out of fuel

Neutrinos • Neutrinos – almost massless particles • No charge • It takes a neutrino about 2 seconds to exit the Sun

Fusion • The rate of nuclear fusion is a function of temperature • Hotter temperature – higher fusion rate • Lower temperature – lower fusion rate • If the Sun gets hotter or colder, it may not be good for life on Earth

What is happening to the amount of Helium in the Sun? • A) Its increasing • B) its decreasing • C) Its staying the same

What is happening to the amount of Helium in the Sun? • A) Its increasing • B) its decreasing • C) Its staying the same

Valence Electrons • Electrons in the outermost occupied shell of an atom • Forms chemical bonds

Ion • Ion – an electrically charged particle created when an atom either loses or gains one or more electrons

Ionic Bond • Ionic bond – chemical bond in which an attractive electric force holds an opposite charge together

Covalent Bond • Covalent bond – a chemical bond in which atoms are held by their mutual attraction for two or more electrons share • Covalent bonds form molecules

Metallic Bonds • A chemical bond in which positively charged metal ions are held together within a “fluid” • Electromagnetic interaction between conduction electrons and gathered in an "electron sea“ • Atoms "share" electrons that float about in a general electron cloud

Charges need to balance • Na ions carry a +1 charge • Cl ions carry a -1 charge • Na+ + Cl- → Na. Cl (Sodium chloride)

• HCl – Hydrogen Chloride • Li 2 O – Lithium Oxide • CO – Carbon Monoxide • CO 2 – Carbon Dioxide

Any Questions?