Electronic Structure of the Atom PDF

Electronic Structure of the Atom  An energy level is a region of definite energy within an atom that electrons can occupy.  There are 2 ways to energise atoms: 1. Supply Heat 2. Supply Electricity  Flame Tests  Spectrum - A spectrum is a band of colours produced when light is separated into its d...

Electronic Structure of the Atom  An energy level is a region of definite energy within an atom that electrons can occupy.  There are 2 ways to energise atoms: 1. Supply Heat 2. Supply Electricity  Flame Tests  Spectrum - A spectrum is a band of colours produced when light is separated into its di erent wavelengths.  spectroscope - needed to show the characteristic line spectrum of an element. used to identify a particular gas. 1. Continuous Spectrum: full range of colours 2. Emission Spectrum: shows distinct lines of certain colours 3. Absorption Spectrum: shows dark lines at specific wavelengths depending on the elements present     Atomic Absorption Spectrometer - used to measure the presence & amount of an element. IR  Paschen series Excited electron falls back to n=3 Visible  Balmer series Excited electron falls back to n=2 UV  Lyman series Excited electron falls back to n=1 Niels Bohr put forward a theory explaining the line spectrum of hydrogen.  He stated that: 1. The energy of the electron in hydrogen is restricted to certain energy values called energy levels. The electron cannot have an energy value between these levels. 2. When an electron moves from a higher energy level (E2) to a lower energy level (E1), a definite amount of energy is emitted in the form of light. The di erence in energy levels can be calculated as follows: E2 – E1 = hf h = Planck’s constant f = frequency of light emitted 3. An electron will move to a higher energy level if it absorbs an amount of energy equal to: E2 – E1 4. Energy levels are given the values: n = 1,2,3,4 etc. Limitations of The Bohr theory: 1. Only worked well for hydrogen 2. Did not take account of the fact that electrons have the properties of waves as well as particles 3. Did not allow for the Heisenberg uncertainty principle 4. Did not explain the discovery of sublevels 5. Did not account for the existence of orbitals Heisenberg Uncertainty Principle: It is not possible to determine at the same time, the exact position & velocity of an electron. Atomic Orbital An atomic orbital is the region around the nucleus where the probability of finding an electron is relatively high (>95%) Energy Levels An energy level is a region of definite energy within an atom that electrons can occupy. Energy Sublevel An energy sub-level is made up of a group of atomic orbitals all of the same energy. Aufbau Principle: Electrons will occupy the lowest sublevel available.