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CHAPTER 4 ATOMIC STRUCTURE • Aristotle (Greek) • Thought all substances were built from either fire, earth, air, water • Thought that atoms of a _________are smooth and round • Thought atoms of a _________were rough and prickly • Dalton’s Atomic Theory (1766) • • • • Evidence for atoms Measured the masses of elements Compounds have ________composition All matter is made up of ____________particles called______, which cannot be divided • 1 All _________are composed of ______ • 2 All atoms of the same element have the____ ______, and atoms of different elements have different masses • 3 ___________contain atoms of more than 1 element • 4 in a particular compound, atoms of different elements always ________the same way • Evidence for subatomic particles – _______and _______are spread throughout the atom – Earnest Rutherford- (1871-1937) • Alpha particles---_____ moving _________charged • All the atoms _________charge is in the _________ • The nucleus is the _____________charged mass located in the center of the atom • Ques.1-5 pg. 105 SECTION 4-2 • Properties of subatomic particles • Protons-- + charged particles, varies among elements • Each nucleus contains at least _____positively charged particle • +charge = _______ • Electron • - charge 1• Found ________the nucleus in an _________cloud or (shell) • • • • • Neutron _________ Found in the ________ Mass almost = to a proton Protons, electrons and neutrons can be distinguished by_____, ___________in an atom and the charge ATOMIC NUMBER AD MASS NUMBER • The atoms of any element contain the _______number of protons • Example there is one proton in the nucleus of every hydrogen atom. There hydrogen has an atomic number of 1 • ATOMIC NUMBER = _________________________ • Atoms of __________elements have different numbers of protons • Sulfur= atomic #= 16 because it has 16 protons in the nucleus • Each ________charge is balanced by a ________charge SO hydrogen has ___ proton and ____ electron sulfur __ protons and ___ electrons • MASS NUMBER= the ______of the _______and ________in the nucleus of the atom • Ex Aluminum= 13 protons+14 neutrons= an atomic mass of 27 • Number of neutrons= ______ _ _______ • Ex. Aluminum 27-13= 14 (#of neutrons) ISOTOPES • • • • When an atom does not have the same ________of neutrons Same atomic number but different mass #’s Ex. Oxygen-16, 17, and 18 All oxygen atoms have 8 protons, but some have 9 or 10 neutrons • Ques. 1-7 pg. 112 • • • • • Energy levels 1 one orbital max __ electrons 2 four orbitals max ___ electrons 3 nine orbitals max ___electrons 4 sixteen orbitals max ___ electrons • Electron configuration—arraignment of _________in the orbitals of an atom • _______levels get filled before higher energy levels----inner to outer • Stable electron configuration is the one in which the electrons are in orbitals with the ______possible energies (ground state) • Ques. 1-5 pg. 118 4-3 Modern Atomic Theory • Niels Bohr-1885-1962 Danish physicist focused on electrons in the electron cloud • Energy levels • Each _________has a _____amount of energy • Electrons closer to the nucleus have ____energy than further away from the nucleus • They move in a less than predicable way • Atomic orbitals – The electron cloud represents ___the orbitals in an atom – An orbital is a region of space around the_______ figure 15 page 117 (copy into notes) – Draw in your notes the Thomson, Rutherford, Bohr, and electron cloud models (pg 115) • An ________in an atom can move _______energy levels when the atoms gain or ____energy • The ____of the jump between orbitals determines the amount of energy ______or ____ • Evidence for movement from one level to another is _____--light is a form of ______-----heat is another cause of ________of electrons from one orbital to another • Electron cloud-how electrons behave in their orbitals • Electrons move like _______in the solar system around the_______, they move in a less than predicable way • When electrons move to a ______energy level they are considered in an _______state • Ex. He, Ne, Ar Kr, Xe find out the names of these elements