Download iClicker PARTICIPATION Question: Development of the Modern

6/25/2015
iClicker PARTICIPATION Question:
Determining Isotopic Abundance
Naturally occurring Germanium consists of stable four
isotopes: Ge-70, Ge-72, Ge-73, Ge-74. Based on the
average atomic mass of Germanium, which isotope is
most abundant?
A. Germanium-70
B. Germanium-72
C. Germanium-73
D. Germanium-74
E. Not enough information has been provided.
Development of the Modern Atomic Theory
In 1803, John Dalton proposed an atomic theory that is still the basis for
many of our theories about the atom.
1. All matter is composed of atoms, which are tiny, indivisible particles.
2. A chemical reaction is a rearrangement of atoms to form different
compounds. Atoms are neither created nor destroyed in a chemical
reaction (the law of conservation of mass).
3. Atoms of one element cannot be converted into another element.
Atoms of an element are identical in mass and other properties, and
are different from every other element.
4. A compound is a combination of atoms of two or more elements in
specific ratios (the law of definite composition).
Understanding Chemical Changes at the Atomic Scale
◦ Some bonds between atoms are broken while new bonds are
formed
◦ Different substances are formed through new combinations of
atoms
To understand & manipulate chemical reactions,
we must be able to COUNT ATOMS & combine
substances in specific PARTICLE RATIOS.
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Relative Masses:
A convenient tool for relating one quantity of particles to another
quantity of particles through measurements of mass
Nut: 1 g
Bolt: 2 g
100 x 12 = 1200
1.2 x
1200 g =
103 objects
100 dozen
=
2400 g
Molar Mass:
A connection between Macroscopic and Particulate nature of matter based on
the relative masses of each atom
Carbon-12: 12 amu
Magnesium-24: ~24 amu
Definition of 1 mole
=
1 mol
=
Molar Mass:
Indicates how many grams are in one mole of the substance
12 g/mol
24 g/mol
Mole / Dozen Analogy
• Like the mole, a dozen of something is a convenient way to talk
about the number of items we tend to buy in those quantities:
1 dozen donuts
= 12 donuts
3 dozen eggs
= 36 eggs
• The mole and the dozen make it easier to talk about large
quantities of some specific item. In the case of a dozen, we are
often specifying a quantity of eggs.
• In the case of a mole, we are specifying a quantity of atoms,
molecules or some other particle on the atomic scale.
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Molar Mass & Avogadro’s Number:
A connection between Macroscopic and Particulate nature of matter
Relative Masses:
Carbon: 12 amu
Magnesium: ~24 amu
6.022 x 1023
particles
12 g
=
1 mol
=
24 g
Molar Mass:
Indicates how many grams are in one mole of the substance
12 g/mol
24 g/mol
The Mole
•
A mole of anything is 6.02214 x 1023 of that particular thing.
•
In Chemistry, we work with very small particles, so we must work
with a very
large quantity of them.
•
The mole is a convenient number to count a large quantity of
particles.
•
We can talk about a mole of anything, but we usually use it to
talk about atoms, molecules, ions, and formula units – Matter
at the microscopic, atomic, particle level.
6.02214 x 1023 is also called Avogadro’s number.
Proceeding clockwise from
the top samples containing
one mole each: copper,
aluminum, iron, sulfur,
iodine, and (in the center)
mercury.
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The mole and counting particles
• We can use molar mass to convert from mass to moles
OR from moles to mass:
• Using Carbon as an example:
12.01 g Carbon = 1 mole of C
𝟏 𝒎𝒐𝒍𝒆 𝒐𝒇 𝑪
𝟏𝟐.𝟎𝟏 𝒈 𝒐𝒇 𝑪𝒂𝒓𝒃𝒐𝒏
OR
𝟏𝟐.𝟎𝟏 𝒈 𝑪𝒂𝒓𝒃𝒐𝒏
𝟏 𝒎𝒐𝒍𝒆 𝒐𝒇 𝑪
• We can use Avogadro’s number to convert from moles
to particles OR from particles to moles:
1 mole = 6.02214 x 1023 particles
𝟔.𝟎𝟐𝟐 𝒙 𝟏𝟎𝟐𝟑 𝑪 𝒂𝒕𝒐𝒎𝒔
𝟏 𝒎𝒐𝒍𝒆 𝒐𝒇 𝑪𝒂𝒓𝒃𝒐𝒏
OR
𝟏 𝒎𝒐𝒍𝒆 𝒐𝒇 𝑪𝒂𝒓𝒃𝒐𝒏
𝟔.𝟎𝟐𝟐 𝒙 𝟏𝟎𝟐𝟑 𝑪 𝒂𝒕𝒐𝒎𝒔
The heart of CHEMISTRY
The MOLE
NA:
Molar Mass:
6.022 x 1023
particles/mol
g/mol
Mass (g)
# of Particles
Density:
g/mL
• atoms
• molecules
• ions
• formula units
Volume (mL)
iClicker Participation Question:
Counting Atoms by Measuring Mass
Which quantity of substance below would contain the
MOST ATOMS?
A. 8 g of He
B. 12 g of Carbon
C. 40 g of Sulfur
D. 60 g of Calcium
E. 80 g of Krypton
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Unit Conversions
• How many grams are in 5 moles of gold (Au)?
• How many moles are in 236.5 g of water (H2O)?
• How many molecules of water are in the quantity
above?
Unit Conversions
How many moles are in 2.99 x 1021 molecules of carbon
dioxide?
How many grams of CO2 are in the quantity above?
Mole Conversions
What is the mass of 3.5 x 1022 atoms of gold?
How many formula units are present in 335 mg of
magnesium chloride (one formula unit = MgCl2)? How
many Chlorine atoms are present?
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How big is one mole?
Imagine you had 1 mole of US Dollars ($6.022 x 1023). If
you spent $1 billion per second, how many years would it
take you to spend all of the money?
This is the same number of carbon ATOMS
that are in 12.01 grams of carbon
iClicker PARTICIPATION Question:
Mole to Mole Conversions
How many moles of Hydrogen atoms are present in 2
moles of ammonium phosphate (NH4)3PO4?
A. 2 moles H
B. 4 moles H
C. 7 moles H
D. 12 moles H
E. 24 moles H
Sapir–Whorf hypothesis: a principle of linguistic
relativity that holds that the structure of a language
affects the ways in which its speakers conceptualize
their world.
Sami people, who live in the northern tips of Scandinavia
and Russia, use at least 180 words to describe snow and
ice (according to Ole Henrik Magga, a linguist of Norway)
Nomenclature:
A systematic language for describing the
regularity and bonding patterns found in chemical
substances
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Pure Substances
Elements:
Compounds:
Only one type of atom
combinations of multiple
elements
Covalent:
Molecular:
Atomic:
Single atoms
Ionic:
Atoms of multiple
Atoms of only one
Atoms of multiple
element connected elements connected elements locked into
into a molecule
into a molecule
a periodic lattice
The Diatomic Elements

Seven elements exist as diatomic molecules in their
elemental form.

For example, Oxygen is an element. However, Oxygen in
the air is not simply O atoms, but as O2 molecules.

The diatomic elements are:
Br2
I2
N2
Cl2
H2
O2
F2
Brinclhof!

Note: These elements are necessarily diatomic only when alone as
elements. They will sometimes have other subscripts in compounds.
Major Categories of Compounds:

Ionic Compounds:
◦ Usually formed through the
combination of a metal (+) and a
nonmetal (-)

Covalent Compounds:
◦ Formed through the combination
of multiple nonmetals bonding
together
◦ The charged particles are
connected in a grid; impossible to
distinguish one unit from another
◦ Individual molecules can be
identified and distinguished from
one another
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Cations
• Metals tend to LOSE electrons.
• Other examples:
Ba  Ba+2 + 2 e
Al  Al+3 + 3 e
Anions

Non-metals generally GAIN electrons.
Other examples:
S + 2e  S2
Cl + 1e  Cl
Predicting the Charges of Monatomic Ions:

The periodic table can help us to determine what the charge on
ions will be.

Noble gases (group 8A) have a very stable electron configuration, and
generally do not form ions. They are inert, or non-reactive.

Ions formed from A - group metals and non-metals
have very predictable charges that can be
determined from their placement on the table.
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General Properties of Ionic Compounds

All ionic compounds are NEUTRAL:


Composed of cations (positive charges) and anions
(negative charges) whose charges cancel (add up to
zero)
The formula unit is the smallest ratio of cations and
anions.
Predicting Formulas of Ionic Compounds

We can always reason out how the charges cancel by adding
them up. However, there is a simpler way:

What is the formula for an ionic compound made up of
aluminum and oxygen?
Al forms +3 ions.

Al+3 O2

O forms 2 ions.
To find the formula, simply write both ions in correct order,
and CROSS charges:
The compound is neutral:
Al2O3
2 x (Al+3) = +6
3 x (O2) = 6
0 (neutral)
Writing & Naming Formulas of Ionic Compounds:

When writing formulas & naming ionic compounds:
 the cation (often the metal) is always written first
 the anion (often a non-metal) is always written second.

The SMALLEST ratio of cation to anion is always written.

The charges on the ions are not written in the formula of the
ionic compound.
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Naming the ANION
If the anion is a non-metal, then follow these 2 steps:
1.
Drop the suffix on the element name.
2.
Add –ide.

Example:
For chlorine, drop the –ine and add –ide.
The name of chlorine as an anion is chloride.

Other Examples:
Fluorine
 fluoride
Oxygen
 oxide
Phosphorus
 phosphide
TRANSITION METALS ARE DIFFERENT

The transition metals, or B-group metals, often form more than
one kind of cation. The names of these elements will include a
roman numeral that indicates the charge.

Also, the metals below the non-metals (p-block) often have
more than one possible charge and require a Roman numeral to
indicate their charge.
Roman Numerals
One = I
Seven = VII
Two = II
Eight = VIII
Three = III
Nine = IX
Four = IV
Ten = X
Five = V
Eleven = XI
Six = VI
Twelve = XII
Commit 1-7 to
memory
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iClicker Participation Question:
Writing the formulas for Ionic Compounds
What would be the proper formula for Zirconium (IV)
oxide?
A. ZrO
B. ZrO2
C. Zr4O
D. Zr2O
E. Zr2O4
Polyatomic Ions
Sulfate Anion:

Polyatomic ions are ions
composed of more than
one atom.

Polyatomic ions may be
cations or anions.

They are covalently bound
groups of atoms that have
lost or gained electrons.

Polyatomic ions are
“molecules with a charge”.
Ion name
Ion Formula
ammonium
NH4+
cyanide
CN–
hydroxide
OH–
nitrate
NO3–
nitrite
NO2–
2–
sulfate
SO4
sulfite
SO32–
hydrogen
sulfate
(bisulfate)
HSO4–
carbonate
CO32–
**Commit those in
RED to memory
Ion name
hydrogen
carbonate
(bicarbonate)
phosphate
hydrogen
phosphate
dihydrogen
phosphate
permanganate
perchlorate
chlorate
chlorite
hypochlorite
Ion Formula
HCO3–
PO43–
HPO42–
H2PO4–
MnO4–
ClO4–
ClO3–
ClO2–
ClO–
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Considering Polyatomic Ions in writing formulas:

What is the formula for the combination of iron (II) and
phosphate ions?

Parentheses must be used when more than one of the
same polyatomic ion is in the formula unit.
Write formulas for these IONIC compounds:
Potassium bromide
Sodium oxide
Strontium phosphide
Aluminum sulfide
Ammonium sulfate
Nickel (II) phosphate
Magnesium nitrite
Lead (IV) selenide
iClicker Participation Question:
Addressing COMMON MISCONCEPTIONS in Naming Ionic Compounds
What is the name for Ti(SO4)2?
A. Titanium Sulfate
B. Titanium Disulfate
C. Titanium (II) Sulfate
D. Titanium (IV) Sulfate
E. Tetratitanium disulfate
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Molecular, Covalent Compounds
• A molecule is a collection of atoms that are covalently connected
together (they share electrons). Typically forms from nonmetals
connected to other nonmetals.
• A molecule acts as a single, free entity and is the smallest unit of
covalent compounds.
• The formula for a molecular, covalent compound is the number
of atoms of various elements in a single molecule.
• Examples: H2O
C12H22O11
SO2
Representations of Molecular Compounds
Taxol:
Structural Formula:
Molecular Model:
Molecular Formula:
C47H51NO14
Names and Formulas for
BINARY Molecular (Covalent) Compounds

Binary molecular compounds are composed of two
non-metals.

The ratios in which they combine are not as
predictable as they are for IONIC compounds.

For example, C and H can form compounds with
many different formulas, including CH4, C3H8,
C50H102.
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Formulas & Naming: Binary Covalent Compounds
Rules for naming molecular compounds:
1. The first element in the formula is named by its name on
the periodic table.
2. The second element is named as it would be if it were
the anion of the element. (Though it is not the anion!)
3. Use prefixes to indicate how many of each element is
present.
Exception: If only one of the FIRST element in the
formula is present, do NOT use the prefix mono-. Just
leave it off.
Prefixes for Naming Covalent compounds:
# of atoms of element
Prefix
1
mono-
Commit prefixes
1-10 to memory
2
di-
3
tri-
4
tetra-
5
penta-
6
hexa-
7
hepta-
8
octa-
9
nona-
10
deca-
11
undeca-
12
dodeca-
Binary Covalent Compounds – Examples

Write the name or formula:
1.
CO
2.
CO2
3.
N2O
4.
NO2
5.
Oxygen difluoride
6.
Disulfur trioxide
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MIXED REVIEW
Write the name or formula:
Sulfur trichloride
6) Manganese (VII) oxide
1) Fe(NO3)2
7) Ca3(PO4)2
2) Iron (II) chloride
8) (NH4)2CrO4
3) P4O10
9) Dinitrogen pentoxide
4) W3P4
10) PbSO4
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