Chapter 4
4.4 Periodicity and Line Spectra Explained
Valence Shell- outermost occupied shell of an atom
(Na and Li both in Group IA both have full inner shell(s) and one electron in outermost occupied (valence) shell. P. 129
Elements with similar chemical properties have identical valence shell configurations. ‘
p.130 (EXCEPT helium- 2 valence electrons, while other elements of group VIII have 8.
The roman-numeral group number directly gives the # of valence-shell electrons of atoms in that group. (A Group Elements)
N=1 1.0eV
N=2 11.2eV
N=3 13.1eV
N=4 13.8eV
N=5 14.1eV
The difference between 2 energies= the amt of energy it will take to move 1 the electron from n=1 to n= 2 (11.2eV- 1.0eV)
Ground State- arrangement of electrons that has the lowest total energy.
(i.e. Hydrogen atoms spend most of their time in the ground state in normal conditions.)
However, when energy is added (ex. heated), its electron can jump to a higher-energy shell.
Excited State- one or more of an atom’s electrons are located in higher-energy shells even though there is room for those electrons in a shell of lower energy. P. 132
Atoms do not stay in the excited state for too long.
There are vacancies at lower-energy levels and the electrons can drop back to down to these levels= RELAXATION
*Atoms returning to the ground state lose the same amount of energy that was used.
An atom can lose energy by:
1. Emit energy as light.
Amount of energy possessed by the light wave during relaxation is the same amt. of energy the electron loses in dropping to a lower energy level p. 133
Bohr’s model accounts for the existence of the line spectra because the electrons in an atom are allowed to possess only certain energies and never anything in between.
4.5 Subshells and Electron Configurations
N=1 (s subshell)
N=2 (s and p)
N=3 (s, p, d)
N=4 (s, p, d, f)
S subshell= 2 electrons
P subshell = 6 electrons
D subshell= 10 electrons
F...