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Be sure to keep up on your reading from your text and studying your notes (scientific method, sigfigs , sci. notation, electron configs , models, etc.). A quiz may be right around the corner… Or not… Or yes… Hint hint. Electron Configuration. Electrons ( e - ’s) and Orbitals. Atomic Models.
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Be sure to keep up on your reading from your text and studying your notes (scientific method, sigfigs, sci. notation, electron configs, models, etc.). A quiz may be right around the corner… Or not… Or yes… Hint hint. Electron Configuration Electrons (e-’s) and Orbitals
Atomic Models • Several models were created to explain the properties observed by the atom. • The charges of the electrons • The charges of the protons • The size, locations, and arrangement • Originally, scientists believed (chronologically) • Solid-Sphere Model (Plum Pudding Model) • Planetary Model (Rutherford’s Model) • Quantum Model (WHAT WE KNOW TODAY)
Atomic Models • Rutherford’s model proposed electrons orbit the atom • This proved J. J. Thompson’s “Plum Pudding Model” was incorrect • States electrons orbited the atom like moons to a planet • Bohr’s model confines e-’s to energy levels • States e-’s can only be certain distances from the nucleus • This distance depends on the energy the e- has • The further away, the higher energy level
Quantum Model • The present-day model of the atom, in which electrons are located in orbitals, is also known as the quantum model • States electrons within an energy level are located in orbitals, regions of high probability for finding a particular electrons. • Does not, however, explain how the electrons move about the nucleus to create these regions
Orbitals • According to the current model of the atom, electrons are found in orbitals • -regions around the nucleus that correspond to specific energy levels • Orbitals are sometimes called electron clouds because they do not have sharp boundaries • Tells where it is likely to find an electron
Electron Configurations • Pauli Exclusion Principle • The principle that states that two particles of a certain class cannot be in the exact same energy state • Electron Configuration • the arrangement of electrons in an atom • Aufbau Principle (German for “building up”) • States that electrons fill orbitals that have the lowest energy first!!
“Building up” ?? • “Building up” refers to the filling of all lower energy “sites” before increasing up in energy • Moving outward away from the (+) nucleus requires more energy for the (-) electrons to maintain the further distance • We have 4 orbitals (spots) that e-’s can go into: • s-orbital (holds ________) d-orbital (holds ________) • p-orbital (holds ________) f-orbital (holds ________)
Electron Configurations • Write out the electron configuration for an element with an atomic number of 20 Atomic # = # of protons = # of electrons 1s22s22p63s23p64s2 We can abbreviate this using the LAST noble gas i.e. [Ar] 4s2
Practice with e- Configurations • Write the electron configuration for an atom of an element whose atomic number is 8. • Write the electron configuration for an atoms of an element whose atomic number is 34. • Write out the electron configuration for Copper.
Electron Configs • Draw these out. • Electrons MUST fill the lower energy levels before moving to the next. Each level is increasing energy.
Electrons and Light • If an electron is in a state of lowest possible energy it is in the Ground State • If an electron gains energy, it moves to an Excited State • An electron in an excited state will release a specific amount of energy as it “falls” back down to the ground state. • This energy is emitted as certain wavelengths of light
Counting Atoms (real chem) • Atomic Mass • The mass of an atoms expressed in atomic mass units (AMU) • The Mole!! • A mole is just a counting unit (a quantity) for really small things (like atoms) • It is 6.0221367 x 1023 of anything • This value is known as Avogadro’s Number
Molar Mass • Molar Mass • The mass in grams of one mole of the element • Has the units of g/mol • 1 mole has 6.022x1023 atoms (particles) • Avogadro’s Number allows us to CONVERT between moles and grams
Practice • Calculate the molar mass of NH3 • Calculate the molar mass of H2SO4 • Calculate the molar mass of NaCl
Practice • Convert 12.5 grams of LiOH to moles LiOH • Convert 0.58 moles of H2O to atoms of water • Convert 1.28 moles of cobalt(II)oxide to mass
Homework • Counting Atoms and Electron Configuration Worksheet • Work on: • e- config for Mn, Fe, and Co • Convert: • 1.85 mol Al g • 8.9 g O mols