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ELEMENTS AND ATOMIC STRUCTURE Chapter 5.5 – Day 2 The Atom The smallest part of an element that is representative of that element. The nucleus is the central region of the atom that contains most of the mass and all the positive charge. The nucleus contains protons (p+) and neutrons (n) Electrons (e-) occupy the space outside of the nucleus. ELEMENTS AND ATOMIC STRUCTURE The Bohr-Rutherford model of the atom suggests that atoms are composed of three types of subatomic particles: protons neutrons electrons PROTONS (p+) Are heavy positively charged particles that are found in a dense positive core of the atom called the nucleus The number of protons in an atom is equal to the element’s ATOMIC NUMBER! (#p) The number of protons determines what element it is! NEUTRONS (n) Are neutral particles that have about the same mass as protons and are also found in the nucleus. The MASS NUMBER is the mass of an atom and is equal to the number of protons plus the number of neutrons in the atom. #p + #n ELECTRONS (e-) Are negatively charged particles with almost no mass that “orbit” the nucleus at different energy levels, also called orbitals or shells. The number of electrons in an atom equals the number of protons, therefore the atoms charge is neutral. Atoms Carbon Fluorine Atomic number =6 Atomic number = 9 Mass number =12 Mass number = 19 #p = 6 #p=9 #n= 12 – 6 = 6 #n = 19 – 9 = 10 #e = 6 #e = 9 phosphorus Bohr Diagrams Bohr Diagrams can be used to show the arrangement of electrons around the nucleus. Electrons are only found in certain “orbits”, “shells” or “energy levels” around the nucleus. Where do the electrons go? Maximum Electrons Level 1 2 electrons Level 2 8 electrons Level 3 8 electrons Level 4 18 electrons HANDOUT – 20 MINUTES Complete the handout by reading pages 185186. Work with a partner if you like. Protons Electrons Neutrons Nucleus Shells Nucleus + ive - ive neutral Same as Atomic Number Mass Number - Atomic Number Same as Atomic Number Neutral Electrons 2, 8, 8 IONS An ion (charged atom) in which the number of electrons is different from the number of protons. The IONIC CHARGE is the numerical value of the electric charge with a plus or minus sign. Give Handout to show examples. HOMEWORK QUESTIONS PAGE 187: 4,5,6abc Ion Worksheet Crossword puzzle (review) – hand in for marks Quiz tomorrow on Chapter 5.1 and 5.5