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, J.J. Thomson) Planetary Model (Neils Bohr’s Model) Quantum Model (Schrödinger and Heisenberg)

Atomic Models Rutherford’s model proposed electrons orbit the atom The atom’s mass is mostly in the nucleus States electrons were in a “fixed orbit” Bohr’s model confines e-’s to energy levels Orbited like moons around a planet 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 ________)

Energy Levels

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 1 mole has 6.022x1023 atoms (particles) 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