Academic Chemistry Chapter 5 Electrons in Atoms Notes

Transcription

1 Academic Chemistry Chapter 5 Electrons in Atoms Notes Name Date ATOMIC MODEL See Atomic Model Timeline worksheet for specifics. ELECTRONS Quantum Mechanical (QM) Model- This is the currently accepted model of the atom. o Erwin Schrödinger wrote an equation which describes. These locations are not definite because of the Heisenberg Uncertainty Principle. Each of the following terms gives a more specific description of where an electron probably is. In Chemistry In CB South, for example o Energy level, n o Sublevel, l o Orbital, ml o Spin, s Energy Levels, n- o An electron may NOT be found. o Higher n = higher energy (typically) o n is called the. o To determine how many electrons fit into a given energy level, use this formula: o The maximum number of electrons is 32. o Electrons will occupy first. Sublevels (subshells), l- Shape Appears # of Orbitals Capacity s Sublevel p Sublevel d Sublevel f Sublevel

2 ELECTRON CONFIGURATIONS Electron Configurations- Electron Configuration PRACTICE o Sulfur (S) o Chromium (Cr) o Cobalt (Co) o Zinc (Zn) o Strontium (Sr) o Selenium (Se) o Molybdenum (Mo) o Mercury (Hg) o Antimony (Sb) o 1s 2 2s 2 2p 6 3s 2 3p 4 o Chlorine (Cl) o 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 o Calcium (Ca) o 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 1 Shorthand notation- To write in shorthand electron configuration notation: o 1 st Find the that is in the row above the element you want o 2 nd Write that noble gas's in [brackets] o 3 rd Then continue with the e configuration starting with the next element Ex- Scandium: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 1 Ex- Chlorine: 1s 2 2s 2 2p 6 3s 2 3p 5 ELECTRON EXCEPTIONS Write the configuration for the following: o Cr: o Cu: What they actually are: o Cr: o Cu: Reason sublevels are the most. sublevels are not as stable as filled, but more stable than others.

3 ORBITAL NOTATIONS & THE RULES Orbital Notations o Use a to represent each. s orbitals have line p orbitals have lines d orbitals have lines f orbitals have lines o Use up/down arrows to represent. o Each line can hold a maximum of electrons. o Example Titanium: 1s 2s 2p 3s 3p 4s 3d FILLING RULES Aufbau Principle- o This is the order we get from reading the Periodic Table. Pauli Exclusion Principle- o This is the electron spin. Either +½ or ½ Hund s Rule o They d rather spread out.

4 ELECTRON IN ATOMS Electron Demonstration try to identify key concepts for electrons moving within an atom Flame Tests o Elements give off characteristic which can be used to identify them. o Electrons energy from the flame (or other heat source). o When a certain amount of energy is reached, which is called a, electrons jump to a higher energy level called the. o When the electrons energy in the form of, this is also called a photon or unit of light, they fall back to the lowest, most energy level called the. VISIBLE LIGHT & THE EM SPECTRUM Visible light exists as a narrow band of that our eyes can detect. o The colors of the rainbow. o Red light has a wavelength of about nanometers and represents frequencies. o Violet light has a wavelength of about nanometers and represents frequencies. Wave Statistics o Amplitude the of the wave from zero to crest. o Wavelength the distance between points in phase. Unit: Symbol: o Frequency the number of cycles (wave peaks) that occur in a unit of time. Unit: Symbol: o Wavelength & frequency are related, meaning that wavelengths go with frequencies and wavelengths go with frequencies.

5 Wave Equation o Formula: o Speed of light is always: o Example 1 - If the frequency of radiation for yellow light is 5.10 x Hz, what is the wavelength? o Example 2 - What is the frequency of radiation with a wavelength of 5.00 x 10-8 m? Electromagnetic Spectrum a grouping of all waves that travel at the speed of light. ATOMIC EMISSION SPECTRA Electrons returning from an energy level emit of specific (specific bands of color). Each element has a emission spectra and therefore is a good way to an element! Additional transitions exist, but we can t see them because our eyes only detect visible light. These series of transitions are called Lyman, Balmer and Paschen. Energy as an electron falls from excited states they release a quantum of energy that can be calculated using Plank s constant and the frequency of the transition. o We will not be calculating these energy transitions in this class.