Physics 102 Atoms to Galaxies Books for Course to Follow Along Discovering the Universe 9th Edition Atoms and Galaxies Atoms Follow along in Discovering the Universe Chapter 4 Section 5 6 and Chapter 16 Section 1 6 Smallest division of matter Makes up chemical properties How to retain property Cut matter to reach smallest piece the atom Properties remain the same and stops at the atom Break atom and matter no longer behaves as it did before All matter is made from atoms Atoms of different types make up different elements in periodic table 92 naturally occurring All atoms made up of different parts o Protons o Neutrons o Electrons Example hydrogen has one proton and one electron going around it helium two neutrons two protons two electrons Protons and neutron found in nucleus Electrons move around nucleus vary by distance Number of neutrons determines the isotope Number of protons determine chemical property Most important element in study of astronomy hydrogen abundance 90 atoms in universe simple basic Second most important element in study of astronomy helium second easiest to make 9 atoms in universe Every other atom in universe is the 1 Universe hydrogen and Helium Bohr Model Atoms are organized by levels of energy Arrangement is different for each element calling levels quantized Electron can change energy by giving or absorbing a photon of light energy Atoms are not like mini solar systems Orbits are not restricted Restriction where electrons can be Electrons cannot exist in places other than the allowed energy level When electron transitions it occurs instantaneously Quantum mechanics describes this behavior Physics 102 Atoms to Galaxies Galaxies Enormous objects held together by gravity Over 100 000 light years across Milky way is a barred spiral galaxy The sun is only one star of billions in milky way Main component of galaxies o Dust o Gas hydrogen and helium o Stars Classified by how they look Hubble 1920 used telescope to determine different galaxies o Classified into tuning fork diagram Elliptical Normal spiral Barred spiral Irregulars Lenticular Different classifications within categories o Spirals determined by how thick center mass and how tightly wound o Elliptical determined by how circular Gravity causes galaxies to cluster together in groups Galaxies can evolve and interact o Can change shape of itself and other galaxies o Pull gas from each other o Can collide combine or pass through each other o Interactions can induce star formation o Stars can also be pulled out o If one galaxy has greater force of gravity then it can over take another galaxy to create on big one