Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW1Questions of the Day•How do elements differ from each other?•What are the four basic states of matter?•How do they depend upon temperature?•What is the condition of atoms in the various states of matter?•How would you describe the difference between temperature and energy?Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UWAdministrative Stuff• Don’t have your textbook yet? It’s on reserve in Oedegard and in the Physics-Astronomy library.• Don’t have the right edition? Scans of the Table of Contents of 3rd, 4th, and 5th editions are on the website, to allow you to cross-check.• Labs are a mix of on-line and written work. Written work will always be turned in during section, usually 1 week after the section where the material was discussed. On-line components are due at various times (see webpage).2Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW3The basic building block of normal matter is the atom• Protons Massive Positive (+) charge• Neutrons Massive No charge (neutral)• Electrons Negligible Mass (me = mp / 1830) Negative (-) chargeNot drawn to scale!“massive”!1.67x10-27kg!Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW4The basic rules of atoms•An atom wants to have as many electrons as protons (i.e. it wants to be electrically NEUTRAL, with no net charge)+ ++++---- -Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW5The basic rules of atoms•The number of protons strongly defines how the atom behaves, chemically. # of protons ELEMENT126826HydrogenHeliumCarbonOxygenIron“Atomic Number”Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW6The Periodic TableEach box is a different element, with a different number of protons.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW7Of all the possible elements, the universe is made up almost entirely of Hydrogen and Helium.•The rest is pollution.HydrogenHeliumOther stuff(“metals”)Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW8Of all the possible elements, the universe is made up almost entirely of Hydrogen and Helium.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW9The basic rules of atoms•Neutrons add mass, but don’t change much about how the atom behaves # of neutrons ISOTOPESame element, but different isotopes!“Atomic Mass”Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW10The basic rules of atoms•The structure of the electrons is affected by the energy of the atom. (More on this later!)Low energy! electrons close in.High energy! electrons further out.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW11The basic rules of atoms•Highly energetic electrons can be stripped from the atom: “Ionization”Leftover positively charged atom is called an “ion”Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW12The basic rules of atoms• Atoms combine to form molecules by sharing electrons, but the nuclei don’t interact (usually).HHH20 = Water!OAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW13An ordinary atom of Helium has 2 protons + 2 neutrons in its nucleus.An atom with: 2 protons is: 1 neutrons 2 electronsA. (green) Neutral HeliumB. (yellow) Ionized HeliumC. (purple) A neutral isotope of HeliumD. (blue) An ionized isotope of HeliumE. (pink) An element other than HeliumAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW14An ordinary atom of Helium has 2 protons + 2 neutrons in its nucleus.An atom with: 2 protons is: 3 neutrons 2 electronsA. (green) Neutral HeliumB. (yellow) Ionized HeliumC. (purple) A neutral isotope of HeliumD. (blue) An ionized isotope of HeliumE. (pink) An element other than HeliumAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW15An ordinary atom of Helium has 2 protons + 2 neutrons in its nucleus.An atom with: 3 protons is: 2 neutrons 2 electronsA. (green) Neutral HeliumB. (yellow) Ionized HeliumC. (purple) A neutral isotope of HeliumD. (blue) An ionized isotope of HeliumE. (pink) An element other than HeliumAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW16An ordinary atom of Helium has 2 protons + 2 neutrons in its nucleus.An atom with: 2 protons is: 2 neutrons 1 electronA. (green) Neutral HeliumB. (yellow) Ionized HeliumC. (purple) A neutral isotope of HeliumD. (blue) An ionized isotope of HeliumE. (pink) An element other than HeliumAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW17Elements, Atoms, & Molecules:What’s the big deal?•Universe is made of elements, atoms, and/or molecules ! raw material for planets, stars, & galaxies•Almost all light in the universe is generated through processes related to elements, atoms, & molecules.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW18Elements occur in many different forms.•Solids"The surface of the moon, taken during the Apollo 17 mission.Interstellar dust cloud !Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW19Elements occur in many different forms.•Solids•Liquids (not much)OceansAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW20Elements occur in many different forms.•Solids•Liquids (not much)•Gas (lots!)OpticalHydrogen GasAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW21Elements occur in many different forms.•Solids•Liquids (not much)•Gas (lots!)•“Ionized” Gas, or Plasma (lots)Star formation regionsAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UWXElements occur in many different forms.•Solids•Liquids (not much)•Gas (lots!)•“Ionized” Gas, or Plasma (lots)States of Matter!!!Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW22The same element can exist in many different states•For example, water.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW23What’s the difference between these states of matter? Temperature alters the structure of the atoms and/or molecules.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW24What is temperature?•Higher Temp ! Higher typical speeds•“Absolute Zero” is where nothing is moving! Matter can never be colder than absolute zero.Low TempHigh TempAstronomy 101, Winter
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