Electron Configuration

Electron Configuration shows placement of the electrons within the atom, focusing on energy levels and pairing I. Electrons can only exist in certain planes, called energy levels. A. Appear like rungs on a ladder, but the spacing decreases as the rung gets further from the nucleus B. Energy increases as rung distance increases

C. Energy is absorbed to move up the ladder and released to move down 1. called a QUANTUM of energy D. Within each energy level is a sublevel. This determines shape of electron occupation

E. Orbitals – location with the highest E. Orbitals – location with the highest probability of finding electrons within a sublevel II. Rules for electron placement A. Aufbau Principle – electrons are placed in lowest energy levels first 1. electrons must start in the first level, and climb up the ladder B. Pauli Exclusion Principle – only 2 electrons can be held in an orbital, and they must have opposite spins

C. Hund’s Rule – every orbital within a C. Hund’s Rule – every orbital within a sublevel gets 1 electron before any gets 2 Periodic Table can be used to determine the order electrons are placed around an atom A. Period = Energy level 1. transition metals, must subtract 1 from period to get correct energy level 2. rare earth metals, must subtract 2 from period to get correct energy level

Light and the Atom I. Quantum Mechanical Model A. Electrons do not orbit, but move randomly about their orbitals 1. can only predict probability of finding an electron in a specific location B. Electrons can move between energy levels by absorbing or releasing energy 1. released energy is called a photon, and is in the form of light

2. can calculate the energy using E = hv E = energy (in Joules) h = planck’s constant = 6.626x 10-34 J*s v = frequency (in seconds-1 or 1/s)

II. Light A. Energy exists on a scale called the electromagnetic spectrum 1. arranged from low energy to high a. Low energy = low frequency = long wavelength 2. can calculate wavelength or frequency using: C = λv C = speed of light (3.00 x 108m/s) λ = wavelength (meter based) v = frequency (1/s)

Frequency – how many wavelengths pass a point in a given amount of time (seconds-1)

Spectrum I. Visible light is a small portion of the electromagnetic spectrum A. Light is observed using a prism in one of 2 ways: 1. Continuous Spectrum – all colors in the visible spectrum with no gaps

2. Bright Line Spectrum – only certain wavelengths are present i. Act like fingerprints. No 2 elements have the same spectrum ii. Allows identification of light sources from space