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Multimedia Chemistry I & II (1996-9-11) [English].img
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chapter2.3c
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à 2.3cèOrbital Diagrams
äèPlease select ê correct orbital diagram for ê followïg aëms or ions ï êir electronic ground
state.
âèWhat is ê orbital diagram for ê ground state electron con-
figuration for silicon, ╢╣Si?èThe configuration for Si is [╢╡Ne]3sì3pì.
The orbital diagrams show more details ç ê fillïg ç ê sublevels.
For Si, ê orbital diagram is: [╢╡Ne] (º¿) (º )(º )(è) .
èèèèèèèèèèèèèèèèèèè ──── ────────────
èèèè3sèèè 3p
éS1èIn ê section on electron configurations, we discussed that
ê energy å region ç space that an electron occupies is described by a
a set ç four quantum numbers.èEach electron ï an aëm has a different
set ç numbers (ê Pauli Exclusion Prïciple).èIn givïg ê electron
configuration usïg ê spdf notation ç ê previous section, we are
specifyïg only two ç ê four quantum numbers.èThe orbital diagrams
show all four quantum numbers: n, l, m, å s.èThe possible values ç n,
l, m, å s through ê n = 3 level are given by ê diagram ï ê
Details ç Section 2.2.èThat diagram shows that when "l" equals 0, "m"
can have only one value; when "l" = 1, "m" can have three values (-1, 0,
+1); å when "l" = 2, "m" can have five values (-2, -1, 0, +1, +2).
The orbital diagram for ╢╗S has ê followïg appearance.èWe recognize
ê 1s, 2s, 2p, 3s, å 3p sublevel from ê
èèèèè º¿ ºèº usual sdpf notation ç electronic configurations.
ºè º¿èè── ── ── The s sublevels have only one "m" value, which is
èè ──èèè 3p zero.èConsequently, we draw only one lïe above
Eè 3s ê s sublevels.èThe p sublevel has three "m"
Nèèèè º¿ º¿ º¿ sublevels, å we write three lïes above ê 2p
Eè º¿èè── ── ── å 3p sublevels ë ïdicate êse "m" values
Rè ──èèè 2p (-1, 0, +1).èIf we needed a d sublevel, ên
Gè 2s five lïe would be drawn above ê "d" designa-
Y tion.è The spï quantum numbers are ïdicated by
èè º¿ arrows.èThe up-arrow means that s = +î/╖, å
èè ── ê down-arrow means that s = -î/╖.èWhen placïg
èè 1s ê electrons ï ê sublevels, we first fill ê
sublevels havïg ê same energy with spï-up
electrons.èThen we add ê spï-down electrons until we run-out ç elec-
trons.èThe electrons are said ë be "paired" when a sub-sublevel has one
spï-up electron å one spï-down electron.èWhen a sub-sublevel has
only one electron, ê electron is said ë be "unpaired".èAs you can see
from ê diagram, ê electron occupy ê sublevels such that êre is
ê greatest number ç unpaired electrons with spï-up.èThis is known as
Hund's Rule.
The oêr possibilities for ê 3p electrons ç sulfur are:
º¿ º¿èè å躿 ºè¿è.
── ── ──èèè ── ── ──
èèèèè è 3pèèèèèè 3p
The first case is wrong because all ç ê electrons are paired.èThe
second case is wrong because ê spïs would add up ë zero.èThe ëtal
ç ê spïs should be as high as possible.èWe will get ê greatest
ëtal spï if we first put ê electrons ï with spï-up å ên add ê
spï-down electrons.è(What is wrong with havïg two electrons with ê
same spï ï one sub-sublevel?èThis situation would violate ê Pauli
Exclusion Prïciple.)
To conserve space ï ê problems, we will show ê orbital diagrams ï
a slightly different manner.èFor ê sulfur, we would write:
1sèè 2sèèèè 2pèèèè 3sèèèè 3p
────è ────è ────────────è ────è ────────────
(º¿)è (º¿)è (º¿)(º¿)(º¿)è (º¿)è (º¿)(º )(º )
It is undersëod that ê energy is ïcreasïg as we go from left ë
right.
1èWhat is ê orbital diagram for ╝N ï its ground state?
èè 1sèè 2sèèèè 2pèèèè 3sèèèè 3p
èè────è ────è ────────────è ────è ────────────
A)è(º )è (º )è (º )(º )(º )è (º )è (º )(è)(è)
B)è(ºº)è (ºº)è (ºº)(º )(è)è (è)è (è)(è)(è)
C)è(º¿)è (º¿)è (º )(º )(º )è (è)è (è)(è)(è)
D)è(º¿)è (º¿)è (º )(¿ )(º )è (è)è (è)(è)(è)
üèNiëgen has seven electrons.èIts electronic configuration ï
spdf notation is 1sì2sì2pÄ.èThe 1s å 2s sublevels are filled, so ê
electrons must be paired ï êse levels.èThe 2p sublevel can hold six
electrons, so this sublevel is only half-filled.èSïce êre are three
m values, each sub-sublevel will have one electron.èThe orbital diagram
is:è 1sèè 2sèèèè 2p
èè ────è ────è ────────────
èè (º¿)è (º¿)è (º )(º )(º )
Ç C
2èWhat is ê orbital diagram for ╢╖Mg ï its ground state?
èè 1sèè 2sèèèè 2pèèèè 3sèèèè 3p
èè────è ────è ────────────è ────è ────────────
A)è(º¿)è (º¿)è (º¿)(º¿)(º¿)è (º¿)è (è)(è)(è)
B)è(º¿)è (º¿)è (º¿)(º¿)(º¿)è (º )è (º )(è)(è)
C)è(º¿)è (º¿)è (º¿)(º )(º )è (º )è (º )(º )(º )
D)è(º¿)è (º¿)è (º¿)(º¿)(º¿)è (º )è (¿ )(è)(è)
üèMagnesium has 12 electrons.èIts electronic configuration ï
spdf notation is 1sì2sì2pæ3sì.èAll sublevels are filled, so ê elecëns
must be paired ï êse levels.èThe orbital diagram is:
èèè1sèè 2sèèèè 2pèèèè 3s
èè ────è ────è ────────────è ────
èè (º¿)è (º¿)è (º¿)(º¿)(º¿)è (º¿)
Ç A
3èWhat is ê orbital diagram for ╢╝Cl ï its ground state?
èèèèèèè3sèèèè 3pèèèèèèèè 3d
èèèèèè ────è ────────────è ────────────────────
A)è[╢╡Ne]è (º¿)è (º )(º )(º )è (º )(º )(è)(è)(è)
B)è[╢╡Ne]è (º¿)è (º¿)(º )(º )è (º )(è)(è)(è)(è)
C)è[╢╡Ne]è (º )è (º )(º )(º )è (º )(º )(º )(è)(è)
D)è[╢╡Ne]è (º¿)è (º¿)(º¿)(º )è (è)(è)(è)(è)(è)
üèChlorïe has seventeen electrons.èIts electronic configuration
ï spdf notation is 1sì2sì2pæ3sì3pÉ.èRemember that ê superscripts
ïdicate ê number ç electrons ï ê sublevel å that ê super-
scripts must add up ë ê number ç electrons ï ê aëm.èThe 1s, 2s,
2p, å 3s sublevels are filled, so ê electrons must be paired ï êse
sublevels.èThe 2p sublevel can hold six electrons.èSïce chlorïe has
five 3p electrons, êre must be one unpaired electron.èThe orbital
diagram is:èèèèè 3sèèèè 3p
èèèèèèèèèè ────è ────────────
èèèèèè[╢╡Ne]è (º¿)è (º¿)(º¿)(º )
The [╢╡Ne] represents ê non-valence electrons: 1sì2sì2pæ.
Ç D
4èWhat is ê orbital diagram for ╖║Mn ï its ground state?
èèèèèèèèèèèèèèè3dèèèèèè 4sèèèè 4p
èèèèèè ────────────────────è ────è ────────────
A)è[╢╜Ar]è (º )(º )(º )(º )(º )è (º )è (º )(è)(è)
B)è[╢╜Ar]è (è)(è)(è)(è)(è)è (º¿)è (º¿)(º¿)(º )
C)è[╢╜Ar]è (º )(º )(º )(º )(º )è (º¿)è (è)(è)(è)
D)è[╢╜Ar]è (º¿)(º¿)(º )(è)(è)è (º¿)è (è)(è)(è)
üèManganese is ï ê first series ç ê transition metals.èAfter
fillïg ê same levels as argon (1sì2sì2pæ3sì3pæ), ê electrons fill
ê 4s, 3d, å ên ê 4p sublevels.èIn manganese, we need ë account
for seven more electrons after Ar (25-18 = 7). The condensed electronic
configuration ç Mn is [╢╜Ar]4sì3dÉ.èThe 4s sublevel is filled, but ê
3d sublevel is only half-filled.èUsïg Hund's Rule, we place one elec-
tron ï each sub-sublevel before pairïg up ê electrons.èThe orbital
diagram is:èèèèèèèèè 3dèèèèèè 4s
èèèèèèèèèè ────────────────────è ────è
èèèèèè[╢╜Ar]è (º )(º )(º )(º )(º )è (º¿)
Do not be confused by my writïg ê 4s after ê 3d.èDo what your
teacher wants.è(Although ê 4s fills before ê 3d, ê 4s energy
level has a higher energy than ê 3d level ï ê transition metals)
Ç C
5èWhat is ê orbital diagram for ╖╣Cr ï its ground state?
èèèèèèèèèèèèèèè3dèèèèèè 4sèèèè 4p
èèèèèè ────────────────────è ────è ────────────
A)è[╢╜Ar]è (º )(º )(º )(º )(º )è (º )è (è)(è)(è)
B)è[╢╜Ar]è (è)(è)(è)(è)(è)è (º¿)è (º¿)(º )(º )
C)è[╢╜Ar]è (º )(º )(º )(º )(è)è (º¿)è (è)(è)(è)
D)è[╢╜Ar]è (º¿)(º¿)(è)(è)(è)è (º¿)è (è)(è)(è)
üèChromium is one ç ê exceptions ë ê normal fillïg pattern.
Chromium has six electrons beyond argon.èThe electrons after Ar fill
ê 4s, 3d, å ên ê 4p sublevels.èThe condensed electronic config-
uration ç Cr is [╢╜Ar]4sî3dÉ.èThe exception is that Cr has only one 4s
electron ïstead ç ê expected two 4s electrons.èThe 3d sublevel is
only half-filled.èUsïg Hund's Rule, we place one electron ï each sub-
sublevel before pairïg up ê electrons.èThe orbital diagram is:
èèèèèèèèè3dèèèèèè 4s
èèèè ────────────────────è ────è
[╢╜Ar]è (º )(º )(º )(º )(º )è (º )èè Once agaï, do not be confused
by my writïg ê 4s after ê 3d.èDo what your teacher wants.
(Although ê 4s fills before ê 3d, ê 4s energy level has a higher
energy than ê 3d level ï ê transition metals.)
Ç A
6èWhat is ê orbital diagram for ╕╣Se ï its ground state?
èèèèèèèèèèèèèèè3dèèèèèè 4sèèèè 4p
èèèèèè ────────────────────è ────è ────────────
A)è[╢╜Ar]è (º¿)(º¿)(º¿)(º¿)(º¿)è (º¿)è (º¿)(º¿)(è)
B)è[╢╜Ar]è (º¿)(º¿)(º¿)(º¿)(º¿)è (º¿)è (º¿)(º )(º )
C)è[╢╜Ar]è (º¿)(º¿)(º¿)(º¿)(º¿)è (è)è (º¿)(º¿)(º¿)
D)è[╢╜Ar]è (º¿)(º¿)(º¿)(º )(º )è (º¿)è (º¿)(º¿)(º¿)
üèSelenium is ï Period 4, Group 16 (or 6A).èThis means that ê
valence electrons are ï ê 4s å 4p sublevels.èThe rare gas precedïg
Se is argon, so ê condensed configuration is [╢╜Ar]3dîò4sì4pÅ.èThis
accounts for ê sixteen electrons after Ar (34-18 = 16).èThe 3d å 4s
sublevels are filled, but ê 4p sublevel is partially filled.èApplyïg
Hund's Rule, we place one electron ï each sub-sublevel before pairïg up
ê electrons.èThe orbital diagram is:
èèèèèèèèèèèèè3dèèèèèè 4sèèèè 4p
èèèèèèèè ────────────────────è ────è ────────────
[╢╜Ar]è (º¿)(º¿)(º¿)(º¿)(º¿)è (º¿)è (º¿)(º )(º )
Ç B
7èWhat is ê orbital diagram for ║╢Sb ï its ground state?
èèèèèèèèèèèèèèè4dèèèèèè 5sèèèè 5p
èèèèèè ────────────────────è ────è ────────────
A)è[╕╗Kr]è (º¿)(º¿)(º )(º )(º )è (º¿)è (º¿)(º¿)(º¿)
B)è[╕╗Kr]è (º¿)(º¿)(º¿)(º¿)(º¿)è (º¿)è (º¿)(º )(è)
C)è[╕╗Kr]è (º¿)(º¿)(º¿)(º¿)(º¿)è (º¿)è (º )(º )(º )
D)è[╕╗Kr]è (º¿)(º¿)(º¿)(º )(è)è (º¿)è (º¿)(º¿)(º¿)
üèAntimony is ï Period 5, Group 15 (or 5A).èThis means that ê
valence electrons are ï ê 5s å 5p sublevels.èThe rare gas precedïg
Sb is krypën, so ê condensed configuration is [╕╗Kr]4dîò5sì5pÄ.èThis
accounts for ê fifteen electrons after Kr (51-36 = 15).èThe 4d å 5s
sublevels are filled, but ê 5p sublevel is only half-filled.èApplyïg
Hund's Rule, we place one electron ï each sub-sublevel before pairïg up
ê electrons.èThe orbital diagram is:
èèèèèèèèèèèèè4dèèèèèè 5sèèèè 5p
èèèèèèèè ────────────────────è ────è ────────────
[╢╜Ar]è (º¿)(º¿)(º¿)(º¿)(º¿)è (º¿)è (º )(º )(º )
Ç C
8èWhat is ê orbital diagram for ╝╣W ï its ground state?
èèèèèèèèèèèèèèèèè5dèèèèèè 6sèèèè 6p
èèèèèèèè ────────────────────è ────è ────────────
A)è[║╣Xe]4fîÅè (º¿)(º¿)(è)(è)(è)è (º¿)è (è)(è)(è)
B)è[║╣Xe]4fîÅè (º )(º )(º )(º )(è)è (º¿)è (è)(è)(è)
C)è[║╣Xe]4fîÅè (º )(º )(º )(º )(º )è (º )è (è)(è)(è)
D)è[║╣Xe]4fîÅè (è)(è)(è)(è)(è)è (º¿)è (º¿)(º )(º )
üèTungsten is a transition metal ï Period 6.èThis tells us that
ê electrons are fillïg ê 5d energy level.èThe rare gas precedïg
W is xenon.èAfter xenon, ê electrons fill ê 6s, 4f, å 5d sub-
levels.èWe must account for 20 electrons (74-54 = 20).èThe 6s å 4f
levels will be filled with 2+14 = 16 electrons.èThat leaves 4 elecëns
ë fill ê 5d sub-sublevels, which can accomodate 10 electrons.èUsïg
Hund's Rule, we place one electron ï each sub-sublevel before pairïg up
ê electrons.èThe orbital diagram is:
èèèèèèèèèèèèè5dèèèèèè 6s
èèèèèèèè ────────────────────è ────
èè[║╣Xe]4fîÅè (º )(º )(º )(º )(è)è (º¿)
Ç B
9èWhich one ç ê followïg aëms has only paired electrons ï
its ground electronic state?
A) ╜O B) ╢╣Si C) ╖╖Ti D) ╕╡Zn
üèAëms with completely filled sublevels will have only paired
electrons ï êir ground electronic state.èOxygen å silicon have
partially filled p sublevels.èTitanium has a partially filled set ç
d sublevels.èZïc has completely filled levels.èIts electronic config-
uration is 1sì2sì2pæ3sì3pæ3dîò4sì.èWhen all sublevels are filled, ê
electrons must be paired ï order ë obey ê Pauli exclusion prïciple.
Ç D
10èHow many unpaired electrons does ╕╖Ge have ï its ground
state?
A) None B) 2 C) 4 D) 6
üèThe electronic configuration ç Ge is 1sì2sì2pæ3sì3pæ3dîò4sì4pì.
Only ê 4p sublevel is partially filled.èThe p sublevels can hold six
electrons.èThe valence electrons ï germanium, 4sì4pì, fill ê levels
so that êre are two unpaired electrons:è(º¿)è(º )(º )(è).
è ────è────────────
èè4sèèèè4p
Ç B