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Isotope Formulae, Electron Configurations & Orbital Diagrams. Isotope Formulae. Provide element’s symbol Mass number mass# = #p + + #n written as a superscript to the left Atomic number atomic# = #p + or #e - written as a subscript to the left. Mass#. X. Atomic#. 12. C. 6. 13. C.
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Isotope Formulae, Electron Configurations & Orbital Diagrams
Isotope Formulae • Provide element’s symbol • Mass number • mass# = #p+ + #n • written as a superscript to the left • Atomic number • atomic# = #p+ or #e- • written as a subscript to the left
Mass# X Atomic# 12 C 6 13 C 6 Isotope Formulae Carbon has two naturally occurring isotopes: carbon-12 and carbon-13
3 H 1 18 F 9 235 U 92 Isotope Formulae Give the isotope formula for each of the following: 1. Hydrogen with 2 neutrons 2. Fluorine with 9 neutrons 3. Uranium with 143 neutrons
Valence Electron(s) • The electron(s) farthest from the nucleus or in the outermost energy level.
Aufbau Principle • Comes from German word meaning “to build” • Electrons will occupy lower energy orbitals first
Pauli Exclusion Principle • An atomic orbital can hold at most two electrons. • If an atomic orbital holds two electrons, they must have opposite spins.
Hund’s Rule • When filling atomic orbitals of equal energy, place electrons with parallel spins in the orbitals first. Then, place the oppositely spinning electrons in to the orbitals.
Electron Configurations • Also describe where electrons live within an atom • It’s like a translation of quantum numbers. • They give the energy level, atomic orbital, and number of electrons residing in the orbital and energy level.
Electron Configurations • Energy level • May be any positive integer • Just like the principal quantum number
Electron Configurations • Atomic Orbital or Sublevel • Represented by letters: s, p, d, f • Translates azimuthal number and magnetic number • s is the same as l = 0 • p is the same as l = 1 • d is the same as l = 2 • f is the same as l = 3
Electron Configurations • Number of Electrons • in either an atomic orbital or a sublevel • max of 2 in the s sublevel • max of 6 in the p sublevel • max of 10 in the d sublevel • max of 14 in the f sublevel
Electron Configurations • Use the periodic table to guide you in writing electron configurations. • Find the link between 2,6,10, and 14 and the periodic table.
# of electrons energy level sublevel/orbital Electron Configurations • Hydrogen 1s1
Electron Configurations • Write the e- configurations of the next 9 elements (through Ne). He… 1s2 Look at the sum of the superscripts… Li… 1s22s1 Be… 1s22s2 B… 1s22s22p1
Electron Configurations C… 1s22s22p2 N… 1s22s22p3 O… 1s22s22p4 F… 1s22s22p5 Ne… 1s22s22p6
Electron Configurations • Shorthand configurations are written by assuming that you can let the symbol of the noble gas preceding the valence electrons represent the e- configuration to that point.
Electron Configurations…shorthand He… 1s2 Li… [He]2s1 Be… [He]2s2 B… [He]2s22p1 C… [He]2s22p2
Electron Configurations…shorthand N… [He]2s22p3 O… [He]2s22p4 F… [He]2s22p5 Ne… [He]2s22p6
Electron Configurations…shorthand Na… [Ne]3s1 Si… [Ne]3s23p2 Cl… [Ne]3s23p5 Ar… [Ne]3s23p6
Electron Configurations…shorthand Ca… [Ar]4s2 Sc… [Ar]4s23d1 Mn… [Ar]4s23d5 Se… [Ar]4s23d104p4
Electron Configurations…shorthand I… [Kr]5s24d105p5 La… [Xe]6s25d1 Ce… [Xe]6s25d14f1 Hg… [Xe]6s24f145d10
Exceptional Electron Configurations…shorthand Cr… [Ar]4s23d4 [Ar]4s13d5 Cu… [Ar]4s23d9 [Ar]4s13d10 Mo… [Kr]5s24d4 [Kr]5s14d5 Ag… [Kr]5s14d10 [Kr]5s24d9
Orbital Diagrams • Show the electron configuration while illustrating the Aufbau Principle, Pauli Exclusion Principle, and Hund’s Rule • Place energy on the y-axis • Use lines to represent orbitals • Use up and down arrows to indicate spin
2px 3px 2py 3py 2pz 3pz Orbital Diagrams (template) 3s E 2s 1s
2px 3px 2py 3py 2pz 3pz Orbital Diagram for H 3s E 2s 1s
2px 3px 2py 3py 2pz 3pz Orbital Diagram for He 3s E 2s 1s
2px 3px 2py 3py 2pz 3pz Orbital Diagram for Be 3s E 2s 1s
2px 3px 2py 3py 2pz 3pz Orbital Diagram for C 3s E 2s 1s
2px 3px 2py 3py 2pz 3pz Orbital Diagram for O 3s E 2s 1s
2px 3px 2py 3py 2pz 3pz Orbital Diagram for P 3s E 2s 1s
Wrap-Up • Write the electron configuration for nitrogen. • Write the orbital diagram for nitrogen.