Chemistry Ch. 5 Notes #2 Electrons in Atoms

Energy of Atoms Energy Levels Where electrons are found Principal Energy Levels (p.e.l.) 7 “orbits” – each has one or more sublevels in it The number of sublevels in any p.e.l. is the same as its number “n”. Ex. P.e.l. 1 has 1……. p.e.l. 2 has 2, etc p.e.l’s are represented by numbers 1-7

Energy of Atoms Sublevels Designated by numbers and letters The # represents the p.e.l The letter refers to the sublevel First 4 sublevels = s, p, d, f Each electron has specific energy Each p.e.l. has as many sublevels as its number “n” Energy level 1 = 1 sublevel = 1s Energy level 2 = 2 sublevels = 2s and 2p Energy level 3 = 3 sublevels = 3s, 3p, and 3d

Energy of Atoms Principal energy level Sublevels 1 1s 2 2s 2p 3 3s 3p 3d 4 4s 4p 4d 4f 5 5s 5p 5d 5f 6 6s 6p 6d 6f

Shapes of Sublevels All s orbitals are spherical. Each new p.e.l. s sublevel is bigger than the last 2s is larger than 1s

Shapes of Sublevels All p orbitals are dumb-bell shaped px, pz, and py each have a different orientation

Energy of Atoms The d and f sublevels do not all have the same shapes….. Inside the sublevels = orbitals Each orbital holds 2 electrons The 2 electrons have opposite “spins” Compared to earth’s rotation on its axis With each new sublevel there are 2 more orbitals available

Energy of Atoms p.e.l # orbitals Max # of e- 2n2 n s p d f 1 - 2 3 4 8 Number of Orbitals Available # orbitals n2 Max # of e- 2n2 n s p d f 1 - 2 3 4 8 5 9 18 7 16 32

Sublevels Orbitals are drawn out as boxes The 3 p orbitals are referenced as px, py, pz Each orbital holds 2 electrons In Mult. Orbital sublevels, each orbital has to have 1 e- of the same spin before they double up (by gaining a second e- of the opposite spin)

Sublevels Electrons always fill from lowest energy levels to highest energy levels No electron can remain in a particular orbital if there is a vacant orbital at lower energy Once you get to the 3rd p.e.l. there is overlap in energy amongst the levels If an electron jumps to a higher level (an “excited” state) it emits frequencies of light (emission spectra) to go back to “ground state”

Sublevels

Electron Configurations The arrangement of electrons among the various orbitals of an atom is called the electron configuration It is written using a notation that tells us the p.e.l. and sublevels that are filled. Every element has a different electron configuration

Electron Configurations Order that sublevels fill…. 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p

Electron Configurations Element Atomic # Orbital Diagram Electron Configuration H 1 He 2 Li 3 Be 4

Electron Configurations Element Atomic # Orbital Diagram Electron Configuration B 5 C 6 N 7 O 8 F 9 Ne 10 Na 11 Mg 12