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Atomic Structure • The smallest part of an element is an _____________________ • All atoms consist of subatomic particles: – ________________ – ________________ – ________________ Nucleus • The ___________of the atom • Contains ______________________of the atom • ____________ and ____________ are found ______ the nucleus of an atom Mass Number =___________________________ Protons • _________________________________ • __________________________________ • 1 proton = 1 atomic mass unit (amu) # protons = ________________________ Neutron • _______________________________ • Found in the _______________ • 1 neutron = 1 amu # neutrons = ____________________________ Electrons • __________________________________ • Found in the ____________________ • Electrons have a very small mass, so we don’t even count it! • Electrons give atoms their _______________________________ • Atoms are neutral so; __________________________________ Shorthand Notation Isotopes • Atoms of the _________________with ________________________________. • Nuclear symbol: Mass # 12 Atomic # 6 C • Hyphen notation: ______________ Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Isotopes + Electrons Nucleus + + Neutron + + + Proton Proton Nucleus + Carbon-12 Neutrons Protons Electrons Nucleus + + + Neutron + Electrons + Carbon-14 Neutrons Protons Electrons Nucleus 6Li 7Li _p+ _n0 _ p+ _n0 2e– 1e– 2e– 1e– Neutron Electrons + Nucleus + + Nucleus Lithium-6 Neutrons Protons Electrons Proton Neutron Electrons + Nucleus + + Nucleus Lithium-7 Neutrons Protons Electrons Proton 17 Cl Isotopes 37 • Chlorine-37 – atomic #: – mass #: – # of protons: – # of electrons: – # of neutrons: Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem 37 17 Cl Average Atomic Mass • weighted _________ of all ________ • on the Periodic Table • round to _________ decimal places Avg. (mass)(%) + (mass)(%) Atomic = 100 Mass Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Calculating Average Atomic Mass You will be given the ____________and the ____________________(how common the isotope is in nature) of the isotope Average Atomic Mass • EX: Calculate the avg. atomic mass of oxygen if its abundance in nature is 99.76% 16O, 0.04% 17O, and 0.20% 18O. Avg. Atomic = Mass = Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Example • Carbon has 6 protons and 6 neutrons, what is Carbon’s mass number? • An isotope of Carbon has 6 protons and 8 neutrons, what is carbon’s mass number? Remember the number of __________ NEVER changes for an element! Example • Carbon has 6 protons and 6 neutrons, what is Carbon’s mass number? C-12 • An isotope of Carbon has 6 protons and 8 neutrons, what is carbon’s mass number? C-14 Remember the number of protons NEVER changes for an element! Isotope Review • Same element different number of __________________ • Different _________________ • Same _____________, therefore the same number of protons and electrons Atomic Structure • ATOMS – Differ by number of _____________ • IONS – Differ by number of _____________ • ISOTOPES – Differ by number of _____________ Electrons • Electrons give elements their __________________________________ • The arrangement of the electrons will determine how it _________ with other substances • Gain electron the atom becomes _______ (_______________) • Lose an electron the atom becomes ___________ (________________) Electrons are found in the ______________ The cloud has regions of space called energy levels • The first energy level holds ____ electrons • The second energy level holds _____ electrons. • The third energy level holds ____ electrons Valence Electrons • Are found _______________________ • Dictate the _________ and ___________ ________________ of an element • Use the periodic table to determine the number of valence electrons. Lewis Dot Diagram • A way to illustrate the number of valence electrons – Use _______for each valence electron – Place the dot ______ each side of the symbol before pairing the electrons – The __________ represents the nucleus plus all the inner electrons for the element. Examples H O N F Ne Electrons and Light • Electrons are normally in the ______________________________ • When the atom is given ___________ the electrons move to the ___________ state. • When the electrons ________ this energy they fall back to the ground state and emit _______________. • Each element has a unique ___________________________ Electromagnetic Spectrum • Electromagnetic Radiation – – A broad range of energetic emissions – made up of photons • Photons – bundles of energy – Travel like waves – Move at the speed of light = 3.0 x 108 m/s – Electromagnetic waves do not require a medium to move Parts of the wave • Amplitude – the height of the wave • Wavelength – the distance between the two successive waves • Frequency – the number of waves that pass a given reference point per second • Wavelength = lamda in units of nm • Frequency = nu in units of 1/s or s-1 What is the difference between these waves?