Periodic Properties

Periodic Properties - Many Electron Atoms and Periodic...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Many Electron Atoms and Periodic Properties . I. Electron Structure A. The Aufbau Principle. 1. We can solve Schrödinger equation only for the hydrogen atom. Therefore, we will build up the structure of many electron atoms in the following way: a. Start with hydrogen solutions. Increase the nuclear charge by one and place another electron in atom. Starting with the hydrogen solutions, use the rules of quantum mechanics to determine the energy and wave function of the two electron system; this is the structure of He. b. To obtain structure of Li, start with the He results, increase nuclear charge by one and add another electron. This process is repeated and the structures of the heavier atoms are obtained by " building out " from lighter atoms. (Aufbau = building out) 2. The results. a. n, l,m l and m s are still good quantum numbers for describing the behavior of the electrons, that is, the electrons exist in hydrogen-like orbitals. b. In the absence of strong magnetic fields, the energy depends on both n and l . The order of the subshells encountered in following the aufbau principle is: 1s<2s<2p<3s<3p<4s<3d<4p<5s<4d<5p<6s. ... c. This sequence can be remembered by the following scheme: 1s 2s 2p 3s 3p 3d Follow the diagonals. 4s 4p 4d 4f 5s 5p 5d 5f 5g 6s 6p 6d 6f 6g 6h 7s 7p 7d 7f 7g 7h 7I 8s 8p 8d……. . 3. The electron structure of an atom is given by writing the electron configuration of the atom. a. Examples element: 1 H 2 He 3 Li 5 B 6 C 7 N electron configuration: 1s 1 1s 2 1s 2 2s 1 1s 2 2s 2 2p 1 1s 2 2s 2 2p 2 1s 2 2s 2 2p 3 32 Ge: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 2 or : 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 2 Could also group according to n, but fill according to the aufbau principle Write the subshells occupied and the number of electrons in the particular subshell as a right-hand superscript.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 b. The most important electrons in determining the physical and chemical properties of an element are the outermost or valence electrons . 1) For the main group elements the valence electrons are all those electrons with the highest value of the principle quantum number n, they will be s and p electrons. 2) The inner electrons are called the core electrons . They are chemically inert. Their main function is to shield the nuclear charge as seen by the valence electrons. 3) Example: electron division in Ge: 32 Ge: 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 2 core valence 4) Some valence configuration are: 3 Li 2s 1 5 B 2s 2 2p 1 6 C 2s 2 2p 2 7 N 2s 2 2p 3 B. Periodic Table and Valence Electron Configuration. 1. Main group elements (Representative elements, s and p-block elements)
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/07/2008 for the course CHEM 1304 taught by Professor Prof.maguire during the Spring '08 term at SMU.

Page1 / 13

Periodic Properties - Many Electron Atoms and Periodic...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online