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Friday, February 1, 2013

Introduction to Chemistry

A sample is found to be slightly compressible and has a definite volume, but indefinite shape. The sample is most likely a
liquid

An example of a chemcial change is
burning gasoline

Boyle's Law is an example of
an indirect mathematical relationship between two variables (pressure and volume)

Choose the state of water in which the water molecules are farthest apart on average.
steam (vapor)

Theories, such as Dalton's Atomic Theory or the Kinetic Molecular Theory of Gases have which of the following in common?
both explain and predict observed phenomena

While an object is falling to the ground, its potential energy due to location is decreasing.
True

When elements combine to form compounds, those compounds have the properties that are completely different from those of the elements from which they were made.
True

Charles' Law states that the volume of a given amount of gas will increase if the temperature of the gas is increased.
True

The element potassium (K) is a good conductor of electricity and is malleable.
True

All gases have fairly low densities.
True

When milk goes "sour", only a physical change has occured.
False

The particles in a solid do not move at all.
False

The main focus of applied research is to gain greater understanding of how the natural world operates.
False

According to the law of conservation of energy, an object stays at constant speed as it falls.
False

The isotope lead-208 contains
126 neutrons

The mass number and identity for an atom composed of 17 protons, 20 neutrons and 17 electrons would be
37, chlorine

How many valence electrons does an arsenic (As) atom have?
5

In shorthand notation, the electron configuration for a calcium atom would be:
2.8.8.2

The atomic mass listed next to each element on the periodic table is the:
average atomic mass based on the relative natural abundance of the isotopes of the element

How many protons are there in an atom of uranium-238?
92

An alpha particle is identical to
a helium-4 nucleus

During beta decay
a neutron turns into a proton

Iodine-131 has a half-life of 8 days. How much of a 10 gram sample remains after 16 days?
2.5 grams

During alpha emission, the mass number of the radioactive isotope
decreases by 4

When a radioactive nucleus transforms spontaneously to a new, different nucleus and emits radiation, the process is called
transmutation

An ionic bond is usually formed between
a metal and a nonmetal

In a molecule of the diatomic element nitrogen (N2), what type of bond exists between the two nitrogen atoms?
a triple covalent bond

In a double bond, two atoms share a total of ______ electrons.
4

Dalton was absolutely correct in his statement that all atoms of the same element are identical.
False

Nuclei are held together by electrical forces.
False

The charge on a stable aluminum (Al) ion would be negative three (3-).
False

The electron configuration for a Si atom would be written as 2.8.8.4.
False

The number of protons is always equal to the number of electrons for any given atom.
True

Compounds must always overall be neutral in charge.
True

A salt sample is place into some water and all quickly dissolves. To this solution, more salt is added and also dissolves. What is the best description of the original solution?
unsaturated

Carbon dioxide contains _____ polar bonds and the entire molecule is best classified as _________.
2, nonpolar

Electronegativity is the attraction an atom has towards
shared electrons

For nonpolar molecules, the most significant type of intermolecular forces are
induced dipole-induced dipole

How are ion-dipole interactions able to break apart the relatively strong ionic bond when an ionic solute dissolves into a polar solvent?
many weaker ion-dipole interactions work together to pull apart the stronger ionic bond

How many atoms of carbon (C) are in 24.0 grams of carbon?
2 moles of atoms

If a molecule has a molecular (or electron) geometry that is tetrahedral, how many substituents are surrounding the central atom of the molecule?
4

It is easy to induce a dipole in an iodine atom because
electrons find it easy to group to one side because of iodine's large size

What type of bond might you expect between a carbon atom and bromine atom?
polar covalent

The total number of valence electrons used in drawing a Lewis structure for PCl3 would be:
26

The correct shape for a methane (CH4) molecule would be:
tetrahedral

What exactly is a hydrogen bond?
a strong dipole-dipole interaction involving a hydrogem atom from one molecule and a very electronegative element from another molecule

When water at 4 degrees Celcius is heated it expands. When water at 4 degrees Celcius is cooled it
expands

When a solid is changed to a liquid state, the solid
absorbs energy

The desert sand is very hot in the day and very cool at night. What does this tell you about the specific heat capacity of the sand?
Its specific heat capacity is small

The term "balanced" as applied to chemical equations means:
the number of atoms of each element is the same on both sides of the equation

A catalyst will
decrease the activation energy for a reaction

What is the mass of a single lithium (Li) atom in amu's ?
6.9

What is the mass of 1 mole of lithium (Li) atoms?
6.9 g

For the balanced reaction:  3  H2  +  N2   ---->   2 NH3, how many moles of ammonia (NH3) will be produced from 4.0 moles of nitrogen (N2)?
8 moles

5.0 grams of iron (Fe)  would have a larger increase in temperature with the addition of 1000 joules of energy than 5.0 grams of gold (Au). You may want to refer to the table of specific heat capacities in chapter 8 of your text to answer this question.
False
If a molecule contains 2 or more polar bonds, than the entire molecule is never nonpolar.
False

Soap and grime are attracted to each other by induced dipole-induced dipole interactions.
True

If a molecule contains only 1 polar bond, than the entire molecule is polar.
True

Reduction can be defined as the
gain of electrons

In an electrochemical battery (galvanic cell)
the anode is where oxidation takes place

Under what conditions does an oxidizing agent donate electrons?
when a reducing agent is present

When two half-reactions are added together in an oxidation-reduction reaction,
there should be no electrons shown in the overall equation.

The chemical reaction that takes place during electrolysis is
forced to take place by the addition of energy

A carbon atom has been oxidized when it
gains oxygen atoms

How many carbons are in butane?
4

A bromine atom has how many valence electrons?
7

For nonpolar molecules, the most significant type of intermolecular forces are
induced dipole-induced dipole

Isotopes are atoms that have
same number of protons, different number of neutrons

When a radioactive nucleus undergoes beta decay, the number of protons
increases by one

The atomic number of an atom is equal to
the number of protons in the nucleus

What would happen to the mass of an iron bar when it rusts? (assume the rust does not fall off the iron bar)
the mass would increase because it is gaining oxygen atoms

When a sodium atom becomes a stable ion, its charge is
+1

Electromagnetic radiation (light) that has a very small wavelength would have
a high frequency

Was the fat isolated from potato chips in lab soluble in water?
no
Alkenes are a type of hydrocarbon derivative.
False

An oxiding agent is oxidized during a chemical reaction.
False

A measurement of 43.22 mL has more uncertainty than a measurement of 43.2 mL.
False

Carbon atoms are most stable when they make four bonds.
True

A measurement of 43.22 mL has more uncertainty than a measurement of 43.2 mL.
True

Silicon is an example of an element that would be classified as a metaloid.
True

Voltaic cells will work spontaneously.
True

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