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

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.

Each energy level has a number called the PRINCIPAL QUANTUM NUMBER, n Currently n can be 1 thru 7, because there are 7 periods on the periodic table

Orbitals and Sublevels There are four different types of sublevels (s,p,d,f). Sublevels are subdivided into orbitals.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

s sublevel: one orbital, maximum of 2 e-

p sublevel : each orbital holds 2 e-, max 6e-

d sublevel: 5 orbitals, each holds 2e-, max 10e-

f sublevel Seven orbitals, each hold 2e- Max 14e-

Sublevels and Orbitals 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. 1st PEL= s orbital; 2nd PEL= s, p orbitals 3rd PEL= s,p,d orbitals; 4th PEL= s,p,d,f orbitals

Electron Configurations A list of all the electrons in an atom (or ion) Must go in order (Aufbau principle) 2 electrons per orbital, maximum We need electron configurations so that we can determine the number of electrons in the outermost energy level. These are called valence electrons. The number of valence electrons determines how many and what this atom (or ion) can bond to in order to make a molecule 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14… etc.

Electron Configuration Rules Aufbau principle: 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.

**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

Order of Electron Sublevel Filling: It does not go “in order” 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d10 7s2 7p6

Order of Electron Sublevel Filling: It does not go “in order” 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d10 7s2 7p6 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p6

s-block: valence electrons are in the s orbital. 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)

d-block: valence electrons are in the d orbitals 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.

Electron Configuration 1s1 # e- within the orbitals sublevels. ●Sum of all e- should equal Atomic # Energy level #. possibilities are 1-7 orbital possibilities are s, p, d, or f 4 orbitals What element has an electron configuration of 1s1?

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

Practice: Ask these questions every time you have to write an electron configuration Lithium: find the element on the periodic table what is the period number? how many shells? what is the group number? how many valence electrons? what subshell(s) does Li have? what is the electron configuration? atomic # = 3 2 2 1 1 s 1s2 2s1

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

Practice: Ask these questions every time you have to write an electron configuration Boron: find the element on the periodic table what is the row #? how many shells? what is the group #? how many valence electrons? what subshell(s) does B have? what is the electron configuration? atomic # = 5 2 2 3 3 p 1s2 2s2 2p1

Orbital Notation 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.

Orbital Notation Rules Pauli’s Exclusion Principle: when filling orbitals with two electrons, each electron must have an opposite spin.