CHEM 111 Fall 2012: OWLBook Chapter 2
OWL Assignments Coming Due this Weekend!! Be
sure to review units and pre-fixes on your own. This
should be material you covered in high school
science.
Accuracy and Precision
• Accuracy = how close you are to the known value
• Precision = how reproducible (similar to each other)
your results are
X
X
X XX
XX
X
X
X
X
XX X
X X
Chapter 2: Elements and Compounds
• Atomic Structure
• Elements and Isotopes
• The Periodic Table
• Covalent Compounds
– Naming
• Ions and Ionic Compounds
– Naming
Atomic Structure
• Protons:
– Determine the identity of the
element
• Neutrons
– With protons in the nucleus
– Stabilize the nucleus (or make it
unstable-radioactive)
– Result in different isotopes
• Electrons
– Exist outside of the nucleus
– Alter the overall charge on an
atom
• Adding or subtracting them makes
ions
Alpha Particle Scattering-helped
determine the structure of the atom
Subatomic Particles (for CHEM 111)
Cathode Ray (electron beam) Tube
Mass Spectrometer
Atomic Symbols
How many protons, neutrons,
electrons are in: 65
30
Zn
76
33
___(what is the element)
Isotopes & Atomic Weight
• Every form of a unique
element is one of its isotopes
– Some elements only have one
isotope.
• Remember-protons are what
make an element
• Isotopes are forms of an
element with different masses
• Adding or subtracting neutrons
from the nucleus makes
isotopes
• Some isotopes are stable
– Some are unstable
• Radioactive
Let’s look at some isotopes…
Isotope
Hydrogen
Symbol
1
1
H
Deuterium
# of Neutrons
___________
Property/Use
0
“normal”
hydrogen-stable
isotope
1
Used to make
“heavy water”
2
Radioactive.
Used to make
“glow in the
dark” sights for
firearms and
other items (not
cheap stuff)
___________
Tritium
Fractional
(isotopic)
Abundance
Atomic Weight
What is the atomic weight of H ?
Isotope
Symbol
1
1
2
1
Hydrogen
Deuterium
Tritium
3
1
H
H
H
# of
Fractional
Neutrons (isotopic)
Abundance
0
1
2
The Periodic Table
Groups, Periods, Main Group (A), Lanthanide & Actinide Elements, Metals, Non-Metals,
Metaloids (semi-metals), Alkali Metals, Alkaline Earth Metals, Transition Elements (B),
Halogens, Noble (“inert”) gases.
What is an allotrope?
Covalent Compounds
• Compounds are formed when two or
more elements join in a defined ratio
• Covalent compounds consist of
elements held together by covalent
bonds
– Covalent bonds are bonds where
electrons are shared between atoms
– The atoms don’t have a positive of
negative charge on them
• Some are named systematically,
some have long used “historical”
names.
Empirical and Molecular Formula
• Empirical formula has
the ratio of atoms
correct, but not
necessarily the absolute
number of each
• HO
• CF2
• Molecular formula has
the absolute number of
each atom in the
molecule
• H2O2 (hydrogen
peroxide)
• C2F4 (Teflon monomer)
Types of Molecular Models
Butanol
• C4H10O1
• Wedge and Dash
– Formula
• Structural Formula
• Ball and Stick
Naming Covalent Compounds
• Binary, non-metal compounds
– Name first element (use prefix if
needed)
– Name second element, using a
prefix if needed
• Some have historical names that
are more commonly used
• H2O
• CO
• CO2
• UF6
• SiO2
• PF5
Naming Inorganic Acids (see trends?)
(think about other names you may know for these)
Ions and Ionic Compounds
• Atoms normally have zero net charge
– # of electrons = # protons
• Ions have gained or lost electrons
– Ions can form from any isotope
– Ions have nothing to do with the nucleus, only the electrons.
Some Monoatomic Ions
What do the numbers mean?
What is a cation? What is an anion?
What trends or patterns do we see?
Are these all the monoatomic ions there are?
Polyatomic Ions
(covalently bonded atoms that carry a charge amongst the whole group)
Excuse me, Sir, but how many of these things are we going
to have to know? My brain’s turning to Jell-O here!
Formulas and Naming Ionic Compounds
• Ions can have charge,
but ionic compounds
should have a net
neutral charge
• One can have Empirical
and Molecular Formulas
for ionic compounds
• Instead of pre-fixes,
IUPAC (International
Union of Pure and
Applied Chemistry)
conventions are used.
• Naming…….
• The name of the cation
(+) comes first.
– If it has more than one
possible charge, that
number comes next
• The name of the anion
comes second.
• CaF2
• LiF
• Fe2O3
• Formulas
– Remember, the charges
MUST balance.
• Use subscripts to make
the charge balance.
• Calcium Chloride
• Zinc Sulfate
• Calcium Nitrate
• Magnesium Phosphate