ElectronConfig - Electron Configuration and Periodicity...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Electron Configuration and Electron Configuration and Periodicity Periodicity Chapter 8
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 Introduction Introduction In 1869 Mendeleev arranged the elements in order of atomic weights to obtain his periodic table. In 1898, Curie’s discovered element Ra in a mixture which was primarily a compound of barium separated from an ore of uranium. Radium gave a new atomic line spectrum different than barium We explain periodic table in terms of electronic structure of atoms.
Background image of page 2
3 Topics of Discussion Topics of Discussion Electron Spin and Pauli Exclusion Principle Building Up Principle and Periodic Table Orbital Diagrams of Atoms; Hund’s Rule Periodicity of Elements Atomic Radius Ionization Energy Electron Affinity Brief Descriptions of the Main-Group Elements
Background image of page 3

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

View Full DocumentRight Arrow Icon
4 Electron Spin and Pauli Exclusion Principle Exclusion Principle Spin quantum number: m s = +1/2 , m s = -1/2 The Pauli Exclusion Principle: no two electrons in an atom can have the same four quantum numbers. An orbital can hold at most two electrons and then only if the electrons have opposite spins.
Background image of page 4
5 Example Example What is the maximum number of electrons in s, p, d, f subshells? Subshell Number of orbitals Maximum # of electrons s(l=0) 1 2 p(l=1) 3 6 d(l=2) 5 10 f(l=3) 7 14 #e =2(2l + 1) #e =2(2l + 1)
Background image of page 5

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

View Full DocumentRight Arrow Icon
6 Building-up Principle Building-up Principle Ground State(g.s.) Electron configuration associated with the lowest energy level of the atom. Every atom has only one Ground State but infinite number of excited states. Building-up(Aufbau) Principle : Electron configurations of the ground states of atoms are obtained by filling the subshells of increasing energy with electrons.
Background image of page 6
7 Example Example Write down the electron configuration for the ground state of 25 Mn. 25 Mn : 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 5 , 25 Mn : [Ar]4s 2 3d 5 Noble-gas core: an inner-shell configuration corresponding to one of the noble gases: ns 2 np 6 Pseudo-noble-gas core: noble gas configuration together with (n-1) d 10 Valence electron: an electron in an atom outside the noble-gas or pseudo-noble-gas configuration
Background image of page 7

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

View Full DocumentRight Arrow Icon
8 Hund’s Rule and Orbital Diagrams Hund’s Rule and Orbital Diagrams Hund’s rule: the lowest energy arrangements of electrons in a subshell is obtained by putting electrons into separate orbitals of the subshell with the same spin QN before pairing electrons
Background image of page 8
9 Magnetic Properties of Atoms Magnetic Properties of Atoms An electron in an atom behaves like a magnet. Two electrons in the same orbital with opposite spins are called paired electrons. Such pairing leads to the cancellation of the electrons magnetic effects. Diamagnetic substances , all electrons are paired. They are not attracted to a magnet (very slightly repeled) Paramagnetic substances , contain unpaired electron(s).
Background image of page 9

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

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/01/2011 for the course CHEMICAL E CHEM-107 taught by Professor Bilinmiyor during the Spring '11 term at Middle East Technical University.

Page1 / 37

ElectronConfig - Electron Configuration and Periodicity...

This preview shows document pages 1 - 10. Sign up to view the full document.

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