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Atomic Structure Atomic Structure: • Location: Where it is on the atom • Charge: Electric charge (positive, negative or neutral) • Mass: how big or small it is Parts of the Atom: NUCLEUS • The small center part of the atom that contains the neutrons and protons • from Greek “karyon”, meaning kernel • Protons and neutron are packed very tightly! • The density is the same as having the entire mass of the sun squeezed into Chicago! Parts of the Atom: ELECTRON CLOUD • The large region around the nucleus that contain the traveling electrons • 100,000 times larger in diameter than the nucleus! • Impossible to determine the exact location of an electron within the cloud. Parts of the Atom: PROTON • Location: the center of the atom • Charge: positive • Mass: About 1 a.m.u, almost 2000 times larger than the electron, slightly smaller than the neutron PROTON From Greek From suffix “ion” meaning “Protos” meaning first subatomic particle Parts of the Atom: NEUTRON • Location: the center of the atom • Charge: neutral • Mass: about 1 a.m.u., almost 2000 times larger than the electron, slightly larger than the proton NEUTRON From the noun “neutral” From suffix “ion” meaning subatomic particle Parts of the Atom: ELECTRON • Location: the outer part of the atom, surrounding the nucleus • Charge: negative • Mass: almost 0 a.m.u., almost 2000 times smaller than the proton and neutron. ELECTRON From the word “electric” From suffix “ion” meaning subatomic particle Comparing Locations: Electrons are on the outside of the atom. They spin around the nucleus in an electron cloud. The protons and neutrons are packed tightly together in the center of the atom. The space between the electron cloud and nucleus is huge! If the nucleus was the size of a golf ball, the electron cloud would be 1.5 miles away! Comparing Charges: Electrons have a negative charge, protons have a positive charge and neutrons have no charge. Comparing Mass: Protons and Nuetrons are almost 2000 times larger than electrons Electron (so tiny, you can’t see it) If a proton was the size of the blue sphere on the left, then the electron would be one pixel of the screen—so small, that you can’t see it! Click here to see website showing this. Getting Smaller…. We now know that matter is made up of even smaller matter: Particles in various combinations Quarks up Leptons charm electron muon electron neutrino muon neutrino tau top down strange bottom tau neutrino Up and Down Quarks 3 quarks (up + up + down) make up a proton 3 quarks (down + down + up) make up a neutron electron proton neutron Bohr Model of a HELIUM ATOM Shell proton + electron N N + - neutron Question: What are some limitations of this model? Answer: Electrons are too large and not in an electron cloud, electrons are too close to the nucleus. ATOMIC STRUCTURE Particle Charge Mass Location proton + ve charge 1 nucleus neutron No charge 1 nucleus electron -ve charge nil shell ATOMIC STRUCTURE Electrons are arranged in Energy Levels or Shells around the nucleus of an atom. • first shell a maximum of 2 electrons • second shell a maximum of 8 electrons • third shell a maximum of 8 electrons Nucleus Contains protons and neutrons 1st shell Can hold up to 2 electrons 2nd shell Can hold up to 8 electrons 3rd shell Can hold up to 8 electrons Adapted from http://www.sciencespot.net/Media/atomsfam.pdf Analyzing Elements on the Periodic Table 4 Be 9.012 Beryllium Atomic number the number of protons in an atom Element Symbol 1, 2 or 3 letters. First letter always capitalized, second always lower case. Atomic Mass the number of protons and neutrons in an atom Element Name * * Number of electrons = number of protons Number of neutrons = Atomic Mass (rounded to nearest) – Atomic Number So let’s try it…. How to draw a Lithium atom First, look at the Periodic Table Second, determine the number of protons (Look at the atomic number) Then determine the number of neutrons (Atomic mass – atomic number) Then determine the number of electrons (Look at the atomic number) 3 Li Lithium 7 Created by G.Baker www.thesciencequeen.net Protons = 3 3 - Li + + + - Lithium - 7 Electrons = 3 Neutrons = 4 2 in the 1st shell, 1 in the 2nd shell (7-3=4) Created by G.Baker www.thesciencequeen.net