Chem 105X
Mon. 9-14-11
Today
Periodic Table
Cations
Anions
Ionic compounds
1. True
2. False
1. After today, please just EMAIL new or changed
clicker serial numbers to [email protected] .
2. Do not skip lab this week! The OSHA-mandated
safety training will happen there. Theme: “Don’t try
this at home.”
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OWL
1. Thursday night assignment NOW due at 12:55 AM
Friday, PDT (11:55 PM ADT)
2. Check out E-book.
- full text in case you need it.
- animations keyed to text
- videos by John Kotz, and Salman Khan (of
www.khanacademy.com fame)
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Thurs night homework as of Wed 10 AM: Some progress.
25
20
15
10
5
0
0
50
100
150
Our advice on homework: Don’t put it off until the last
night. NOW is the time to develop good study habits.
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1A 2A
3B 4B 5B 6B 7B ----8B----- 1B 2B 3A 4A 5A 6A 7A 8A
Please know names and
formulas of the elements
inside the red box.
Some help remembering elements?
http://www.privatehand.com/flash/elements.html
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“Main Group” elements
1A 2A
3B 4B 5B 6B 7B ----8B----- 1B 2B 3A 4A 5A 6A 7A 8A
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1A 2A
3B 4B 5B 6B 7B ----8B----- 1B 2B 3A 4A 5A 6A 7A 8A
“Transition” elements
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1A 2A
3B 4B 5B 6B 7B ----8B----- 1B 2B 3A 4A 5A 6A 7A 8A
Lanthanides & Actinides
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1A 2A
3B 4B 5B 6B 7B ----8B----- 1B 2B 3A 4A 5A 6A 7A 8A
Rare Earth
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http://en.wikipedia.org/wiki/Rare_earth_element
Alkali metals: shiny metals that are chemically reactive.
2 Na + H2O H2 + 2 NaOH + heat
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Try it!
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Winner of the 2002 Ig Nobel Prize in Chemistry –
Theodore Gray and his hand-carved periodic table.
http://www.theodoregray.com/PeriodicTable/index.html
(Check out “sodium party” link at this web site.)
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Excellent book! Personal
history of the young
Oliver Sacks who as a
kid was obsessed with
the Periodic Table.
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Alkaline earth metals
Halogens
Eight elements exist as
diatomic molecules X2
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-Cations
-Anions
-Ionic Compounds
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Ionic compounds contain CATIONS (+) and ANIONS (-).
CATION “CAT-eye-on” The “t” looks like “+” CA+ION.
ANION
“AN-eye-on”
(opposite charge from cation)
All chemical compounds are electrically neutral.
For ionic compounds,
the total amount of (+) charge = total amount of (-) charge.
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CATIONS
Metals form exclusively IONIC compounds, as Cations (+).
Metal atoms in Groups 1A, 2A, and 3A lose electrons to form “inert
gas configuration”. That is, same number of electrons as the NEXT
SMALLER inert gas.
1A 2A
3A
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Potassium ion K+ forms from K atom by…
150
Adding a positron (+1)
Removing an electron (-1)
Adding two positrons and
removing one electron.
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A
1.
2.
3.
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Potassium ion K+ forms from K atom by…
1.
2.
3.
Adding a positron (+1)
Removing an electron (-1)
Adding two positrons and
removing one electron.
Positrons exist (inside accelerators), but have almost
nothing to do with chemistry.
K atom contains 19 protons (+19) in the nucleus and 19
electrons. When you remove an electron, there are still
19 protons, but only 18 electrons. 19 – 18 = +1
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Group 1 atoms: Li Li+ + one electronLi+ ion has the same number of electrons as a He atom.
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Group 2 atoms:
Mg loses 2 electrons to form Mg2+ , which has the Neon
electron configuration.
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What is the charge on a barium ion
(Ba) (as commonly found in nature)?
-2
-1
0
+1
+2
57
48
41
2
1
0
-1
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-2
1.
2.
3.
4.
5.
162
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What is the charge on a barium ion (as
commonly found in nature)?
1.
2.
3.
4.
5.
-2
-1
0
+1
+2
All group 2A elements, including Mg,
form the 2+ ion in compounds.
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Transition metals have
various charges: from
+1 to +4.
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Cations, continued.
The ONLY non-metal, polyatomic cation
we will encounter is ammonium ion NH4+.
Hydrogen ion
H+
NH4+
NH3
Ammonia
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Anions
-monatomic anions
-polyatomic anions
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Monatomic anions:
Xy
These non-metals GAIN electrons to
achieve an inert gas electron
configuration.
y = -3 -2 -1
NAME: N3- is Nitride Nitrogen
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Polyatomic ions - like a molecule, but with total charge > or < 0.
All but two contain O. Those are called “oxoanions”.
You need to KNOW NAMES and FORMULAS of these ions as part of your
chemistry vocabulary. These ions are shown on p. 75 and Oxoanion Table on the
course website.
+1
-1
-2
NH4+
OH(hydroxide)
NO2- (nitrite)
NO3- (nitrate)
ClO- (hypochlorite)
ClO2- (chlorite)
ClO3- (chlorate)
ClO4- (perchlorate)
CN(cyanide)
CH3CO2- (acetate)
MnO4- (permanganate)
HCO3- (hydrogen carbonate)
HSO3- (hydrogen sulfite)
HSO4- (hydrogen sulfate)
H2PO4- (dihydrogen phosphate)
CO32- (carbonate)
SO32- (sulfite)
SO42- (sulfate)
CrO42- (chromate)
Cr2O72- (dichromate)
HPO42- (hydrogen
phosphate)
-3
PO43(phosphate)
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Compounds
y = -3 -2 -1
Ionic compound between lithium and sulfur: Li2S
Lithium ALWAYS forms 1+ cation. Sulfur ALWAYS forms (in
monatomic ions anyway 2- anion. Therefore need 2x as many Li as S.
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You need to KNOW NAMES and FORMULAS of the
polyatomic ions on previous table. This is your chemistry
vocabulary. P. 75 in text And Oxoanion Table on the
course website.
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http://chem.uaf.edu/keller/Courses/105Fa11/IonsTable/IonsIndex.htm
NB. Seeing the ion structures on this webpage requires
the Chime plugin for IE (Windows only).
-,
2-,
MnO4 CrO4 and
Cr2O72- are not shown
here, but are required.
Not
required
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What do these polyatomic anions look like?
- Atoms tied together with covalent bonds in a definite geometry (as in a
molecule), but with 1 or more extra electrons.
- We’ll put off a discussion of the details of bonding until later in the
semester, but here is a picture of the computed structure of HCO3-.
Approximate outer limit of electrons
The red color means that region is rich in
negative charge (slight excess of
electrons). The blue color indicates a
region relatively poor in electrons,
“partially positive” is the term sometime
used. The H of the OH group is like this.
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