1 Chemistry MAC NOTES: Electron Unit Electromagnetic radiation differs for wave length, wave frequency, and wave energy BUT not wave speed (ALL travel at the speed of light). Electromagnetic radiation differs for wave length, wave frequency, and wave energy BUT not wave speed (ALL travel at the speed of light). As wave length increases, wave frequency and wave energy decreases and vice versa. As wave length increases, wave frequency and wave energy decreases and vice versa. Visible (white) light is a part of the electromagnetic spectrum and can be remembered as ROY G. BIV. Visible (white) light is a part of the electromagnetic spectrum and can be remembered as ROY G. BIV. Electrons absorb and release various types of electromagnetic radiation in the form of packets of energy called quanta. Electrons absorb and release various types of electromagnetic radiation in the form of packets of energy called quanta.

2 Chemistry MAC NOTES: Electron Unit An absorption spectrum for an element shows a colored background with missing bands of visible light absorbed by electrons moving from their ground state to their excited state. An absorption spectrum for an element shows a colored background with missing bands of visible light absorbed by electrons moving from their ground state to their excited state. An emissions spectrum for an element shows a black background with colored bands of visible light released (emitted) by electrons moving from their excited state to their ground state. An emissions spectrum for an element shows a black background with colored bands of visible light released (emitted) by electrons moving from their excited state to their ground state. Electrons can absorb and release energy outside visible light, such as Infrared or Ultraviolet. Electrons can absorb and release energy outside visible light, such as Infrared or Ultraviolet. The absorption and emission spectra of each element is unique, like a finger print. The absorption and emission spectra of each element is unique, like a finger print.

3 Chemistry MAC NOTES: Electron Unit The quantum mechanical model provides a four- part address for each electron. The quantum mechanical model provides a four- part address for each electron. Quantum number 1 (n) are major energy levels, from #1-#7. Quantum number 1 (n) are major energy levels, from #1-#7. Quantum number 2 are sub-energy levels and are designated as s, p, d, and f.Quantum number 2 are sub-energy levels and are designated as s, p, d, and f. Quantum number 3 are the positions in space (orientation) of orbitals. Quantum number 3 are the positions in space (orientation) of orbitals. Quantum number 4 is the spin (clock-wise or counter clock-wise) of each electron in an orbital. Quantum number 4 is the spin (clock-wise or counter clock-wise) of each electron in an orbital. Every electron has a unique 4-part address. Every electron has a unique 4-part address.

4 Chemistry MAC NOTES: Electron Unit The quantum mechanical model is guided by four principles—the Heisenberg uncertainty principle; the Aufbau principle, the Pauli exclusion principle, and Hund’s rule. The quantum mechanical model is guided by four principles—the Heisenberg uncertainty principle; the Aufbau principle, the Pauli exclusion principle, and Hund’s rule. Three different notations are used to show the arrangement of electrons in the electron cloud— an electron configuration; orbital filling diagram, and an electron dot diagram. Three different notations are used to show the arrangement of electrons in the electron cloud— an electron configuration; orbital filling diagram, and an electron dot diagram. The preceding (smaller) noble gas (column 18 element) can be used to write an abbreviated electron configuration or orbital filling diagram. The preceding (smaller) noble gas (column 18 element) can be used to write an abbreviated electron configuration or orbital filling diagram.