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CHEM 111 Chapter Notes - Chapter 1: Chemical Formula, Dimensional Analysis, Atomic-Force MicroscopyExam


Department
Chemistry
Course Code
CHEM 111
Professor
Prof
Study Guide
Final

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1
CHAPTER 1 | Matter, Energy, and the Origins of the Universe
1.1. Collect and Organize
In Figure P1.1(a) we are shown “molecules” each consisting of one red sphere and one blue sphere and in
Figure P1.1(b) we have separate blue spheres and red spheres. In each figure we are to identify whether the
substance(s) depicted is a solid, liquid, or gas and if the figures show pure elements or compounds.
Analyze
A pure substance (whether element or compound) is composed of all the same type of molecule or atom, not a
mixture of two kinds. An element is composed of all the same type of atom and a compound is composed of
two or more types of atoms. Solids have a definite volume and a highly ordered arrangement where the particles
are close together, liquids also have a definite volume but have a disordered arrangement of particles that are
close together, and gases have disordered particles that fill the volume of the container and are far apart from
each other.
Solve
(a) Because the particles each consist of one red sphere and one blue sphere, all the particles are the same—this
is a pure compound. The particles fill the container and are disordered, so these particles are in the gas phase.
(b) Because Figure P1.1(b) shows a mixture of red and blue spheres, this is depicting a mixture of blue element
atoms and red element atoms. The blue spheres fill the container and are disordered, so these particles are in the
gas phase. The red spheres have a definite volume and are slightly disordered, so these particles are in the liquid
phase.
Think about It
Remember that both elements and compounds may be either pure or present in a mixture.
1.2. Collect and Organize
In Figure P1.2(a) we are shown “atoms” of only red spheres and in Figure P1.2(b) we have “molecules”
consisting of two red spheres or two blue spheres. In each figure we are to identify whether the substance(s)
depicted is a solid, liquid, or gas and if the figures show pure elements or compounds.
Analyze
A pure substance (whether element or compound) is composed of all the same type of molecule or atom, not a
mixture of two kinds. An element is composed of all the same type of atom and a compound is composed of
two or more types of atoms. Solids have a definite volume and a highly ordered arrangement where the particles
are close together, liquids also have a definite volume but have a disordered arrangement of particles that are
close together, and gases have disordered particles that fill the volume of the container and are far apart from
each other.
Solve
(a) Because all the atoms are of the same type, Figure P1.2(a) depicts a pure element. The particles take up a
definite volume and are ordered, so this element is in the solid phase.
(b) Because there is a mixture of blue diatomic molecules and red diatomic molecules, Figure P1.2(b) depicts a
mixture of two elements. Both the blue and red diatomic particles fill the container’s volume and are highly
disordered; the mixture depicted is in the gas phase.
Think about It
Elements do not need to be present as single atoms. They may be diatomic as in H2 or Br2, or even more highly
associated as in S8 or P4.
1.3. Collect and Organize
In this question we are to consider whether the reactants as depicted undergo a chemical reaction and/or a phase
change.

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

2 | Chapter 1
Analyze
Chemical reactions involve the breaking and making of bonds in which atoms are combined differently in the
products compared to that of the reactants. In considering a possible phase change, solids have a definite
volume and a highly ordered arrangement where the particles are close together, liquids also have a definite
volume but have a disordered arrangement of particles that are close together, and gases have disordered
particles that fill the volume of the container and are far apart from each other.
Solve
In Figure P1.3 two pure elements (red–red and blue–blue) in the gas phase recombine to form a compound
(red–blue) in the solid phase (ordered array of molecules). Therefore, answer b describes the reaction shown.
Think about It
A phase change does not necessarily accompany a chemical reaction. We will learn later that the polarity of the
product will determine whether or not a substance will be in the solid, liquid, or gaseous state at a given
temperature.
1.4. Collect and Organize
In this question we are to consider whether the reactants as depicted undergo a chemical reaction (either
recombination or decomposition) and/or a phase change.
Analyze
Chemical reactions involve the breaking and making of bonds in which atoms are combined differently in the
products compared to that of the reactants. In considering a possible phase change, solids have a definite
volume and a highly ordered arrangement where the particles are close together, liquids also have a definite
volume but have a disordered arrangement of particles that are close together, and gases have disordered
particles that fill the volume of the container and are far apart from each other.
Solve
In Figure P1.4 we see that no recombination of the diatomic molecules occurs. The pure element (red–red)
condenses to a slightly disordered phase while the other element (blue–blue) remains in the gas phase.
Therefore, answer a describes the reaction pictured.
Think about It
Cooling of air in this fashion to different temperatures separates the components of air.
1.5 Collect and Organize
From the space-filling model shown, we are to write the formula for the chemical represented.
Analyze
From the Atomic Color Palette shown, on the inside back cover of the textbook, we see that this model contains
three hydrogen atoms bonded to a carbon atom which in turn is bonded to an O–H unit.
Solve
H3COH or CH4O
Think about It
This model represents methanol, and the presence of the O–H unit classifies it as an alcohol. Sometimes
methanol is named “wood alcohol.”
1.6. Collect and Organize
From the ball and stick model of acetone shown, we are to write the chemical formula.
Analyze
From the Atomic Color Palette shown on the inside back cover of the textbook, we see that this model contains
two CH3 units bonded to a C–O unit.

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Matter, Energy, and the Origins of the Universe | 3
Solve
H3C(CO)CH3 or C3H6O
Think about It
Acetone is classified as a ketone and is a useful solvent. It is the main component in nail-polish remover.
1.7. Collect and Organize
This question considers if and how matter and energy are related. In particular, we consider whether the sun is
all mass or all energy.
Analyze
Einstein showed that matter and energy are interconvertible through E = mc2.
Solve
The sun is an example where matter is being changed into energy through nuclear fusion reactions. Therefore,
both students are correct.
Think about It
Through Einstein’s equation we see that a little bit of mass contains a great deal of energy locked into the nuclei
of the atoms.
1.8. Collect and Organize
In this question, we consider how elements and compounds compare.
Analyze
Compounds can be made from the elements and have different types of atoms in them. Elements are composed
of atoms all of the same kind.
Solve
Compounds are different from elements in that they are made up of two or more elements, these elements can
be separated from each other (but elements cannot be separated further), and compounds have different
chemical and physical properties from the elements that compose them. Elements are also rarely found in
nature. Compounds are similar to elements in that they are composed of atoms, have definite physical and
chemical properties, and can be isolated in pure form.
Think about It
By combining the different elements with each other, we can arrive at many, many compounds which are used
as fuels, medicines, plastics, etc.
1.9. Collect and Organize
For this question we are to list some chemical and physical properties of gold.
Analyze
A chemical property is seen when a substance undergoes a chemical reaction thereby becoming a different
substance. A physical property can be seen without any transformation of one substance into another.
Solve
One chemical property of gold is its resistance to corrosion (oxidation). Gold’s physical properties include its
density, color, melting temperature, and electrical and thermal conductivity.
Think about It
Another metal that does not corrode (or rust) is platinum. Platinum and gold, along with palladium, are often
called “noble metals.”
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