SHELLS, SUBSHELLS, AND ORBITALS - scienceattech.com

155 SHELLS, SUBSHELLS, AN

- Bohr's model predicted that energy levels (called S
how electrons were arranged around an atom. But

SHELL: Equivalent to Bohr's energy levels.
all the same distance from the nucleus.
the SAME) energy.

- Shells are numbered (1-... - El
numbered from 1 to 7)

- Higher numbers correspond to g
energy, and larger size!

- Higher shells can hold mor

ND ORBITALS

SHELLS) were enough to describe completely
t there's more to it!

. Electrons in the same SHELL are
They all have SIMILAR (but not necessarily

lements on the periodic table have shells

greater distance from the nucleus and greater

re electrons than lower shells!

156

SUBSHELLS: Within a SHELL, electro
nucleus! These different "paths" ar

- SHAPES of regions of spa

"s" subshell
(a spherical region)

- Som
pictu

"d" subshell See p 334-3

ons may move in different ways around the
re called SUBSHELLS
ace that electrons are able to exist in.

"p" subshell
(a dumbbell shaped region)

me atoms also have "f" subshells (not
ured)

335 for nicer drawings of the subshells.

157

ORBITALS - are specific regions o

- The SHAPE of an orbital is d
- The ENERGY of an orbital is
in AND the kind of SUBSHELL

- Each orbital may, at most

ARRANGEMENT OF SHELLS, SUBSHELLS, AND

- Shells are numbered. Each shell can con
number:

1st shell: ONE possible subsh
2nd shell: TWO possible subs
3rd shell: THREE possible subs
4th shell: FOUR possible subs
... and so on

of space where electrons may exist

defined by the SUBSHELL it is in
s defined by both the SHELL the orbital is
L it is in
t, contain TWO ELECTRONS

D ORBITALS

ntain the same number of SUBSHELLS as its

hell (s)
shells (s, p)
shells (s, p, d)
shells (s, p, d, f)

158

- Each subshell can contain one or more ORBITALS
are to arrange an orbital of that shape around the

"s" subshell in 1 "p" subshell: Th
One possible Maximum
Maxoirmieunmta2tioenlectrons
orbital

- There are five possible orbitals in a "d" subs

Maximum 10 electrons
in 5 orbitals

S, depending on how many different ways there
e nucleus.

hree possible orientations
m 6 electrons in 3 orbitals

shell, and 7 possible orbitals in an "f" subshell!
Maximum 14 electrons
in 7 orbitals

159 ENERGY DIAG
- We can map out electrons around an atom

5p

4d
5s

4p
E
N 3d

E 4s
R

G 3p
Y

3s

2p
2s

1s

GRAM
m using an energy diagram:

p

d
s

p
d

s

p

s

"1s" means first shell,
"s" subshell

p

s Each blank represents an

ORIBITAL which can hold up to
TWO electrons

s

160 L
5p
E 4d
N 5s
E 4p
R 3d
G 4s
Y 3p
3s

2p
2s

1s

Let's look at some example atoms:
Magnesium: Z=12 , 12 electrons

Outermost electrons of magnesium
"valence electrons". These electrons
are involved in chemical bonding!

161 5p

E 4d
N 5s
E 4p
R 3d
G 4s
Y
3p

3s

Atoms

2p to end

This is c

2s bonds
a scien

1s

Aluminum: Z = 13

Aluminum has THREE valence electrons!
(All electrons in the outer shell are valence
electrons!)

tend to form ions or chemical bonds in order
up with filled outer "s" and "p" subshells.
called the "octet" rule. (Not all chemical
follow this - it's a RULE OF THUMB, not
ntific law!)

162 Exam
V
5p

4d
5s

4p

E 3d
N

E 4s
R

G 3p

Y
3s

2p

2s In ionic com
to become

compounds

1s so that it ha

mple: Oxygen, Z = 8

Valence electrons for oxygen. (6 electrons)

Oxygen needs two more electrons
to complete its outer "p" subshell!
mpounds, oxygen has gained two electrons
the oxide ion (2- charge). In molecular
s, oxygen shares electrons with other atoms
as a share in eight electrons in its outer shell!

163 ELECTRON CONFIG
- A shorthand way to write about electron arra

Shell Numb
and
subshell

Vale
SHELL
THRE

GURATION
angement around an atom.
ber of electrons in the subshell!

ence electrons are the ones in the outermost
L, not just the last subshell. Aluminum has
EE valence electrons.

164 two

elements

wide ELECTRON CONFIGURATION

IA

1 H IIA

2 Li Be ten elements wide

3 Na Mg IIIB IVB VB VIB VIIB VIIIB

4 K Ca Sc Ti V Cr Mn Fe Co N

5 Rb Sr Y Zr Nb Mo Tc Ru Rh

6 Cs Ba La Hf Ta W Re Os Ir

7 Fr Ra Ac Rf Db Sg Bh Hs Mt

"s" block: last electron in these atoms is in a
"p" block: last electron in these atoms is in a
"d" block: last electron is these atoms is in a

Helium is part
of the "s" block!

N AND THE PERIODIC TABLE
VIIIA

six elements wide

IIIA IVA VA VIA VIIA He
B C N O F Ne

IB IIB Al Si P S Cl Ar
Ni Cu Zn Ga Ge As Se Br Kr
Pd Ag Cd In Sn Sb Te I Xe

Pt Au Hg Tl Pb Bi Po At Rn

"inner" transition metals go here

an "s" orbital!
a "p" orbital!
a "d" orbital

165 - To write an electron configuration usi
and count up the electrons until you re
IA

1 H IIA
2 Li Be
3 Na Mg IIIB IVB VB VIB VIIB VIIIB

4 K Ca Sc Ti V Cr Mn Fe Co
5 Rb Sr Y Zr Nb Mo Tc Ru Rh
6 Cs Ba La Hf Ta W Re Os Ir
7 Fr Ra Ac Rf Db Sg Bh Hs Mt

Example: Phosphorus (P):

A shortcut: "Noble gas core" notation starts at

ing the periodic table, start at hydrogen,
each your element!

VIIIA
IIIA IVA VA VIA VIIA He

B C N O F Ne
IB IIB Al Si P S Cl Ar
Ni Cu Zn Ga Ge As Se Br Kr
Pd Ag Cd In Sn Sb Te I Xe
Pt Au Hg Tl Pb Bi Po At Rn
"inner" transition metals go here

t the previous noble gas instead of hydrogen: