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Name: _______________________ Date: _________ Current Atomic Models Refining Nuclear Models • In 1913, Danish physicist, Niels Bohr, refined Rutherford's idea by adding that the electrons were in orbits around the nucleus. Rather like planets orbiting the sun. With each orbit only able to contain a set number of electrons. • He proposed a ___________________ or Orbit model The Bohr Model 1. Electrons revolve around the nucleus in specific _____________ (shells), or __________________________. • 2. An atom has energy levels. Electrons can only exist in these energy levels, not in between. • 3. When an atom is in the ground state, the electrons exist in the energy levels _____________________________________. • 4. If an atom receives, energy, the atom becomes excited and electrons _________________________________________________________. Ground State • The lowest energy state of an atom • Electrons in the first energy level have the lowest potential energy since they are located closest to the nucleus. • Excited State • An atom with _________________________________ than in the ground state because electrons have “jumped” to a higher energy level. • Electrons with higher potential energy occupy orbits farther from the nucleus. The _____ an electron is from the nucleus, the ______ its energy! Current Atomic Model • Electrons act like __________ (because they have a mass) and _________ (because they have certain frequencies corresponding to their energy levels) • Electrons are located in orbitals around the nucleus that correspond to specific energy levels • Electron clouds = orbitals that do not have sharp boundaries, but shows 3D region where electrons are most probable to be found. • ____________________ Model or ____________ Model proposed by Louis de Broglie & Erwin Schrodinger Electron Configuration • Arrangement of electrons • Each atom has a distinct ___________________________. • The ____________________ electron configuration is found on the periodic table in the lower left hand corner of each box. Classify the following as ground state electron configurations or excited state electron configurations. Element ground state electron configurations or excited state electron configuration lithium 1-2 calcium 2-8-7-3 excited chlorine 2-8-7 ground aluminum 2-7-4 excited neon 2-7-1 excited sodium 2-8-1 ground potassium 2-8-7-2 excited exited The configuration listed on the periodic table is the ground state electron configuration. In the chart below, draw the ground state and excited state electron configurations Element He O Na F Al Mg Br Ground State Excited State Element Ground State Electron Configuration Ion Ion’s Electron Configuration Na Na + Mg Mg +2 Fe Fe +3 Al Al +3 Li Li +1 Quantum • Electrons can only absorb or release energy in discrete, specific amounts. • The amounts, or bundles of energy are called __________ (or _________) corresponding to differences in energy levels of the orbitals/shells. Electrons and Light • An atom emits energy when the electron falls from high energy levels to lower energy levels. This energy is in the form of ____________________. • If the wavelength is in the ___________________________, the energy can be seen as color. Light Emission • Each move from a particular energy level to a lower energy level will release light of a specific wavelength. • When certain elements are excited, they give off energy of a distinctive color as the electron fall back down to lower energy levels. These colors are specific and can be used to __________________________ (Flame Test). Spectral lines • If high voltage is applied to hydrogen gas confined in a gas tube, called a gas discharge tube, light is emitted. If this light is passed through a prism, a series of bright lines of distinct colors is produced. Bohr reasoned that these different colored bands of light were actually quanta of corresponding energy. These quanta were emitted as electrons of hydrogen atoms returned from their higher levels in the excited state to their lower levels in the ground state. Bright Line Spectra • Bright line spectrum = the series of bright __________ produced when excited electrons _____________ to their original energy levels • Each element has its own unique set of spectral lines which can therefore be used to identify the elements presence. Valence Electrons • Electrons that occupy the valence energy level • Valence Electrons= found in ______________________ energy level Na 2-8-1 Cl 2-8-7 • Atoms can have a maximum of 8 valence electrons Lewis Dot Diagrams (Electron Dot Diagrams) • Represent the arrangement of electrons around the nucleus. • ____________ are the DOTS. • _____________ is the symbol. • ONLY REPRESENT _______________ ELECTRONS!! • Fill one side first, then one on each side before you pair electrons. Na B O Mg Cl Ne Si H N