Periodic Properties

# Periodic Properties - Many Electron Atoms and Periodic...

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

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.

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

View Full Document
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) a. Valence electrons are s and p electrons b. All elements in the same group have the same valence electron configuration. 1) Group 1 (alkali metals) H Li Na K Rb Cs Fr 1s 1 2s 1 3s 1 4s 1 5s 1 6s 1 7s 1 All group 1 elements have an s 1 valence configuration 2) Group 17 (halogens) F Cl Br I At 2s 2 2p 5 3s 2 3p 5 4s 2 4p 5 5s 2 5p 5 6s 2 6p 5 All group 17 elements have an s 2 p 5 valence electron configuration c. For the main group elements
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern