nuclear charge increases electron shielding increases electron shielding remains constant
TRANSCRIPT
PERIODIC TRENDS
• Coulomb’s Law• Nuclear Charge• Electron Shielding• Atomic Size• 1st Ionization Energy• Electronegativity• Reactivity
TRENDS
Nuclear Charge Increases
Nuc
lear
Cha
rge
Incr
ease
sEl
ectr
on S
hiel
ding
Incr
ease
s
Electron Shielding Remains Constant
5
BBoron
11
3
LiLithium
7
4
BeBeryllium
9
As you go across a period atomic size decreases because the pull of the nucleus (nuclear charge) increases but electron shielding remains constant. The nucleus is able to pull the electrons closer (Coulomb’s law).
Atomic Size
TRENDS
Nuclear Charge Increases
Nuc
lear
Cha
rge
Incr
ease
s
Atom
ic S
ize
Incr
ease
Elec
tron
Shi
eldi
ng In
crea
ses
Electron Shielding Remains ConstantAtomic Size Decreases
1st Ionization Energy
--
-- -
-
-
-
-
- -+11The energy required to remove the outermost electron from an atom.
As you go across a period 1st ionization
energy increases.
As you go down a group 1st ionization energy decreases.
Additional Electron shielding and increased distance from the nucleus makes removing the outermost electron much easier.
Increasing nuclear charge without any additional shielding makes removing the outermost electron more difficult.
TRENDS
Nuclear Charge Increases
Nuc
lear
Cha
rge
Incr
ease
s
Atom
ic S
ize
Incr
ease
Elec
tron
Shi
eldi
ng In
crea
ses
Electron Shielding Remains ConstantAtomic Size Decreases1st Ionization Energy Increases
1st Io
niza
tion
Ener
gy D
ecre
ases
Electronegativity
--
-- -
-
-
-
-
- -+11A measure of an atom or group of atom’s tendency to attract electrons
As you go across a period Electronegativity increases.
As you go down a group Electronegativity
decreases.
Additional Electron shielding and increased distance from the nucleus makes adding a new electron more difficult
Increasing nuclear charge (pull) without any additional shielding makes makes adding an electron easier.
TRENDS
Nuclear Charge Increases
Nuc
lear
Cha
rge
Incr
ease
s
Atom
ic S
ize
Incr
ease
Elec
tron
Shi
eldi
ng In
crea
ses
Electron Shielding Remains ConstantAtomic Size Decreases1st Ionization Energy Increases
1st Io
niza
tion
Ener
gy D
ecre
ases
Electronegativity Increases
Elec
tron
egati
vity
dec
reas
e
Reactivity
For now we can think of an atom’s
tendency to lose or gain electrons as its
reactivity.
So atoms that lose electrons very easily or
have a strong affinity for electrons are considered
the most reactive.
Nuclear Charge Increases
Nuc
lear
Cha
rge
Incr
ease
s
Atom
ic S
ize
Incr
ease
Elec
tron
Shi
eldi
ng In
crea
ses
Electron Shielding Remains ConstantAtomic Size Decreases1st Ionization Energy Increases
1st Io
niza
tion
Ener
gy D
ecre
ases
Electronegativity IncreasesEl
ectr
oneg
ativi
ty d
ecre
ases
Metals: Reactivity decreasesM
etal
s: R
eacti
vity
Incr
ease
Non
met
als:
Rea
ctivi
ty d
ecre
ases
Nonmetals: Reactivity Increases
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Assignment
1st Ionization energy is the amount of energy needed to remove the outermost electron in an atom.2nd Ionization Energy level is the energy required to remove the next electron.
QUESTION: Will sodium have a higher or lower 2nd Ionization energy compared to its first Ionization energy? Explain this in terms of the inverse square law, Coulomb’s law and electron shielding.
ESSAY QUIZ GRADE: Explain periodic trends in first ionization energy, electronegativity, atomic size and reactivity in terms of Coulomb's
law, nuclear charge and electron shielding. BE THOROUGH!