CHEM 1150 Lecture Notes - Atomic Orbital, Electron Affinity
Periodic Trends video
Zeff (z effective): attractive pull that outermost e- will feel towards nucleus
○
Atomic size:
§
As move across periodic table (# of protons incr.), atom size
decreases
§
Adding protons to nucleus, Zeff becomes larger! Even though adding
electrons to outermost energy level, recall that electrons in the
same energy level are not as good as shielding! So as a result,
attractive forces (Zeff) dominate
§
As you move down a group in the periodic table, the atoms become
larger. Electrons in inner orbitals are better at shielding. Outer
electrons do not feel Zeff (more e-'s b/w outermost e- and nucleus,
inner electrons really good at shielding, so as a result atom gets
larger)
§
Going across, adding protons (and also electrons, but to the
same energy level)
Going across, when e-'s on same energy level/ row, not
good at shielding against each other
So Zeff dominates
◊
®
□
Going down, increasing energy levels
So more inner electrons that are shielding you
effectively (inner orbitals shield better)
More energy levels b/w you and nucleus
◊
®
As a result, getting bigger, and not only that, more
shells
So Zeff not as big going down
◊
®
□
Use logic, if more e- bigger atom□
§
Ionic vs Atomic Radius
Cation is smaller than its parent (neutral) atom b/c
removing e-'s
®
Anions are larger than neutral atom b/c gaining e-'s
®
Zeff rationalize trend among common ions
®
□
§
○
Ionization energy: energy required to completely remove 1 mole of e-'s
from 1 mole of gaseous atoms
§
1 mole of atoms + energy = 1 mole of atoms + 1 mole of e-
§
Going down group IE decreases slightly
§
As you go to the right, IE increased due to Zeff
Makes sense when go back to Zeff b/c a lot easier to remove
an e- when Zeff small or e- is the outermost e- (bottom left
corner)
□
□
§
Super hard to remove e- from top right corner □
§
When see big jump in I.E. go from removing valence electrons to
removing core electrons
§
○
Electron affinity
Opposite of ionization energy
§
Addition of 1 mole of e- to 1 mol of atoms in gaseous state
§
1 mole + 1 mole e- --> 1 mole ions + E
§
§
§
More negative in bottom left b/c hardest to add e- b/c
really far from nucleus & shielded from nucleus (by e-'s)
so smallest Zeff (not gonna feel it, no longer as
effective)
®
Top right: greatest pull to nucleus to really easy to add
e-, really hard to remove e-, this why anions
®
□
§
§
○
Trends in metallic behavior
§
Shiny, ductile, and conduct electricity
§
Metals lose e-'s when forming compounds
Reactive metal easily form cations□
Going from left to right, metals become less metallic (go into
non-metals)
□
Top to bottom, becoming more metallic b/c bottom e-'s
easier to lose (not as closely held to nucleus)
□
§
○
-
Quantum Numbers Videos
Schrodinger Equation
Problem: how do we come up w/ an atom if we can't locate the e-
that's in it?
§
Solution: Schrodinger used wave eq's to describe the atom and its
electrons! Solving the wave functions gives you info on the probable
location of e-'s in an atom
§
§
§
so solving for wave functions w/in an atom which represent atomic
orbitals
§
An atomic orbital is specified by 3 quantum numbers
n, l, and nl□
§
○
-
Video notes: CHEM 1150 Fall 2014 Periodic Trends
and CHEM 1150 Fall 2014 Quantum Numbers
Monday, April 2, 2018
10:18 PM
Periodic Trends video
Zeff (z effective): attractive pull that outermost e- will feel towards nucleus
○
Atomic size:
§
As move across periodic table (# of protons incr.), atom size
decreases
§
Adding protons to nucleus, Zeff becomes larger! Even though adding
electrons to outermost energy level, recall that electrons in the
same energy level are not as good as shielding! So as a result,
attractive forces (Zeff) dominate
§
As you move down a group in the periodic table, the atoms become
larger. Electrons in inner orbitals are better at shielding. Outer
electrons do not feel Zeff (more e-'s b/w outermost e- and nucleus,
inner electrons really good at shielding, so as a result atom gets
larger)
§
Going across, adding protons (and also electrons, but to the
same energy level)
Going across, when e-'s on same energy level/ row, not
good at shielding against each other
So Zeff dominates
◊
®
□
Going down, increasing energy levels
So more inner electrons that are shielding you
effectively (inner orbitals shield better)
More energy levels b/w you and nucleus
◊
®
As a result, getting bigger, and not only that, more
shells
So Zeff not as big going down
◊
®
□
Use logic, if more e- bigger atom□
§
Ionic vs Atomic Radius
Cation is smaller than its parent (neutral) atom b/c
removing e-'s
®
Anions are larger than neutral atom b/c gaining e-'s
®
Zeff rationalize trend among common ions
®
□
§
○
Ionization energy: energy required to completely remove 1 mole of e-'s
from 1 mole of gaseous atoms
§
1 mole of atoms + energy = 1 mole of atoms + 1 mole of e-
§
Going down group IE decreases slightly
§
As you go to the right, IE increased due to Zeff
Makes sense when go back to Zeff b/c a lot easier to remove
an e- when Zeff small or e- is the outermost e- (bottom left
corner)
□
□
§
Super hard to remove e- from top right corner □
§
When see big jump in I.E. go from removing valence electrons to
removing core electrons
§
○
Electron affinity
Opposite of ionization energy
§
Addition of 1 mole of e- to 1 mol of atoms in gaseous state
§
1 mole + 1 mole e- --> 1 mole ions + E
§
§
§
More negative in bottom left b/c hardest to add e- b/c
really far from nucleus & shielded from nucleus (by e-'s)
so smallest Zeff (not gonna feel it, no longer as
effective)
®
Top right: greatest pull to nucleus to really easy to add
e-, really hard to remove e-, this why anions
®
□
§
§
○
Trends in metallic behavior
§
Shiny, ductile, and conduct electricity
§
Metals lose e-'s when forming compounds
Reactive metal easily form cations□
Going from left to right, metals become less metallic (go into
non-metals)
□
Top to bottom, becoming more metallic b/c bottom e-'s
easier to lose (not as closely held to nucleus)
□
§
○
-
Quantum Numbers Videos
Schrodinger Equation
Problem: how do we come up w/ an atom if we can't locate the e-
that's in it?
§
Solution: Schrodinger used wave eq's to describe the atom and its
electrons! Solving the wave functions gives you info on the probable
location of e-'s in an atom
§
§
§
so solving for wave functions w/in an atom which represent atomic
orbitals
§
An atomic orbital is specified by 3 quantum numbers
n, l, and nl□
§
○
-
Video notes: CHEM 1150 Fall 2014 Periodic Trends
and CHEM 1150 Fall 2014 Quantum Numbers
Monday, April 2, 2018
10:18 PM
Periodic Trends video
Zeff (z effective): attractive pull that outermost e- will feel towards nucleus
○
Atomic size:
§
As move across periodic table (# of protons incr.), atom size
decreases
§
Adding protons to nucleus, Zeff becomes larger! Even though adding
electrons to outermost energy level, recall that electrons in the
same energy level are not as good as shielding! So as a result,
attractive forces (Zeff) dominate
§
As you move down a group in the periodic table, the atoms become
larger. Electrons in inner orbitals are better at shielding. Outer
electrons do not feel Zeff (more e-'s b/w outermost e- and nucleus,
inner electrons really good at shielding, so as a result atom gets
larger)
§
Going across, adding protons (and also electrons, but to the
same energy level)
Going across, when e-'s on same energy level/ row, not
good at shielding against each other
So Zeff dominates
◊
®
□
Going down, increasing energy levels
So more inner electrons that are shielding you
effectively (inner orbitals shield better)
More energy levels b/w you and nucleus
◊
®
As a result, getting bigger, and not only that, more
shells
So Zeff not as big going down
◊
®
□
Use logic, if more e- bigger atom
□
§
Ionic vs Atomic Radius
Cation is smaller than its parent (neutral) atom b/c
removing e-'s
®
Anions are larger than neutral atom b/c gaining e-'s
®
Zeff rationalize trend among common ions
®
□
§
○
Ionization energy: energy required to completely remove 1 mole of e-'s
from 1 mole of gaseous atoms
§
1 mole of atoms + energy = 1 mole of atoms + 1 mole of e-
§
Going down group IE decreases slightly
§
As you go to the right, IE increased due to Zeff
Makes sense when go back to Zeff b/c a lot easier to remove
an e- when Zeff small or e- is the outermost e- (bottom left
corner)
□
□
§
Super hard to remove e- from top right corner □
§
When see big jump in I.E. go from removing valence electrons to
removing core electrons
§
○
Electron affinity
Opposite of ionization energy
§
Addition of 1 mole of e- to 1 mol of atoms in gaseous state
§
1 mole + 1 mole e- --> 1 mole ions + E
§
§
§
More negative in bottom left b/c hardest to add e- b/c
really far from nucleus & shielded from nucleus (by e-'s)
so smallest Zeff (not gonna feel it, no longer as
effective)
®
Top right: greatest pull to nucleus to really easy to add
e-, really hard to remove e-, this why anions
®
□
§
§
○
Trends in metallic behavior
§
Shiny, ductile, and conduct electricity
§
Metals lose e-'s when forming compounds
Reactive metal easily form cations□
Going from left to right, metals become less metallic (go into
non-metals)
□
Top to bottom, becoming more metallic b/c bottom e-'s
easier to lose (not as closely held to nucleus)
□
§
○
-
Quantum Numbers Videos
Schrodinger Equation
Problem: how do we come up w/ an atom if we can't locate the e-
that's in it?
§
Solution: Schrodinger used wave eq's to describe the atom and its
electrons! Solving the wave functions gives you info on the probable
location of e-'s in an atom
§
§
§
so solving for wave functions w/in an atom which represent atomic
orbitals
§
An atomic orbital is specified by 3 quantum numbers
n, l, and nl□
§
○
-
Video notes: CHEM 1150 Fall 2014 Periodic Trends
and CHEM 1150 Fall 2014 Quantum Numbers
Monday, April 2, 2018 10:18 PM
Document Summary
Video notes: chem 1150 fall 2014 periodic trends and chem 1150 fall 2014 quantum numbers. Zeff (z effective): attractive pull that outermost e- will feel towards nucleus. As move across periodic table (# of protons incr. Even though adding electrons to outermost energy level, recall that electrons in the same energy level are not as good as shielding! So as a result, attractive forces (zeff) dominate. As you move down a group in the periodic table, the atoms become larger. Electrons in inner orbitals are better at shielding. Outer electrons do not feel zeff (more e-"s b/w outermost e- and nucleus, inner electrons really good at shielding, so as a result atom gets larger) Going across, adding protons (and also electrons, but to the same energy level) Going across, when e-"s on same energy level/ row, not good at shielding against each other. So more inner electrons that are shielding you effectively (inner orbitals shield better)
