Wave-Mechanical Model of the Atom. Aim: To write orbital notation and electron configurations representing the wave mechanical model of the atom.

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Jemima Anderson
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1 Wave-Mechanical Model of the Atom Aim: To write orbital notation and electron configurations representing the wave mechanical model of the atom.

2 Wave-Mechanical Model of the Atom Atoms contain protons, neutrons and electrons. Electrons are found in orbitals (region of most probable location), occupying the volume of the atom.

3 Orbitals and Sublevels There are four different types of sublevels (s,p,d,f). Each orbital within a sublevel can hold a maximum of two electrons. The s sublevel is just 1 orbital and only holds 2 electrons. The p, d, and f sublevels have multiple orbitals and can hold more electrons

4 Orbitals and Sublevels s sublevel; 1 orbital= 2e - max p sublevel; 3 orbitals= 6e - max d sublevel; 5 orbitals= 10e - max f sublevel; 7 orbitals= 14e - max The size of an energy level determines how many orbitals fit. 1 st PEL= s orbital; 2 nd PEL= s, p orbitals 3 rd PEL= s,p,d orbitals; 4 th PEL= s,p,d,f orbitals

5 Electron Configuration Rules Aufbau rule: electrons fill the orbitals with the lowest energy first to minimize the energy of the atom (ground state). The Aufbau rule accurately predicts the electron configuration of most elements* *Exceptions: transition elements and heavier elements* Exceptions occur because some elements are more stable with fewer electrons in some sublevels and more in others.

6 **Exceptions** d orbitals contain more energy than s. Electrons will go into an s orbital from the next energy level before going into a d orbital within the current energy level. f orbitals contain more energy than s and p. Electrons will go into s, p orbitals from the next energy level and the s orbital from two energy levels higher before filling the f orbitals in the current energy level. The order of levels filled looks like this: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p

7 Order of Electron Subshell Filling: It does not go in order 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 4p 6 5s 2 5p 6 6s 2 6p 6 7s 2 7p 6 3d 10 4d 10 5d 10 6d 10 4f 14 5f 14

8 Order of Electron Subshell Filling: It does not go in order 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 4p 6 5s 2 5p 6 6s 2 6p 6 7s 2 7p 6 3d 10 4d 10 5d 10 6d 10 4f 14 5f 14 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 2 5f 14 6d 10 7p 6

9 Electron Configuration Rules Hunds rule: when filling orbitals with electrons, each electron will first half-fill all the orbitals within a sublevel before pairing with another electron in a half-filled orbital. Atoms at ground states tend to have as many unpaired electrons as possible.

10 Electron Configuration Rules Pauli s Exclusion Principle: when filling orbitals with two electrons, each electron must have an opposite spin.

11 The period # and block letter of the element should match the last sublevel in the electron configuration s-block: valence electrons are in the s orbital. Alkali metals and Alkaline earth metals and Helium. (Groups 1 & 2). p-block: valence electrons are in the p orbitals. Main group elements. (Groups 13 to 18)

12 d-block: valence electrons are in the d orbitals. Transition metals (Groups 3 to 12). f-block: valence electrons are in the f orbitals. bottom two removed rows. Lanthanide and actinide series.

13 Electron Configuration Energy level #. possibilities are 1-7 1s 1 sublevel possibilities are s, p, d, or f 4 sublevels # e- within the orbitals of the sublevel. Sum of all e- should equal Atomic # What element has an electron configuration of 1s 1?

14 Practice: Ask these questions every time you have to write an electron configuration Lithium: 1. find the element on the periodic table 2. what is the row #? 3. how many shells? 4. what is the group #? 5. how many valence electrons? 6. what subshell(s) does Li have? 7. what is the electron configuration?

15 Practice: Ask these questions every time you have to write an electron configuration Lithium: 1. find the element on the periodic table 2. what is the period number? 2 3. how many shells? 2 4. what is the group number? 1 5. how many valence electrons? 6. what subshell(s) does Li have? 7. what is the electron configuration? 1 s atomic # = 3 1s 2 2s 1

16 Practice: Ask these questions every time you have to write an electron configuration Boron: 1. find the element on the periodic table 2. what is the row #? 3. how many shells? 4. what is the group #? 5. how many valence electrons? 6. what subshell(s) does B have? 7. what is the electron configuration?

17 Practice: Ask these questions every time you have to write an electron configuration Boron: 1. find the element on the periodic table 2. what is the row #? 2 3. how many shells? 2 4. what is the group #? 3 5. how many valence electrons? 6. what subshell(s) does B have? 7. what is the electron configuration? 3 p atomic # = 5 1s 2 2s 2 2p 1

18 Abbreviated Electron Configurations Write the chemical symbol the noble gas previous to the element on the periodic table between brackets: Ex: [Kr] This stands for the electron configuration of krypton, which is 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 Write the number of the next highest energy level in the sequence and fill all remaining electrons for the element. Ex 1) Write the abbreviated electron configuration for Iodine. Long hand: 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 5s 2 4d 10 5p 5 Short hand/abbreviated: [Kr]5s 2 4d 10 5p 5

ELECTRONIC STRUCTURE OF ATOMS

ELECTRONIC STRUCTURE OF ATOMS Electron Spin The electron: spins around its own axis acts as an tiny magnet (any moving electrical charge creates a magnetic field around itself) can spin in either of 2