Transcript Chemical Bonding

Chemical Bonding
Regents Review
2. Which combination of atoms can form a polar
covalent bond?
A) N and N
B) H and H
C) Na and Br
D) H and Br
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Correct Answer: Option D - H and Br
3. As a bond between a hydrogen atom and a sulfur
atom is formed, electrons are:
A) Shared to form a covalent bond
B) Shared to form an ionic bond
C) Transferred to form an ionic bond
D) Transferred to form a covalent bond
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Correct Answer: Option A - Shared to form a
covalent bond
4. Atoms of which element can bond to each other
to form chains, rings, and networks?
A) Hydrogen
B) Fluorine
C) Oxygen
D) Carbon
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Correct Answer: Option D - Carbon
5. Which element has an atom with the greatest
attraction for electrons in a chemical bond?
A) Arsenic
B) Nitrogen
C) Bismuth
D) Phosphorus
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Correct Answer: Option B - Nitrogen
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Electronegativity, denoted by symbol χ, is a chemical
property that describes the ability of an atom (or, more rarely,
a functional group) to attract electrons (or electron density)
towards itself in a covalent bond.
6. Which formula represents a polar molecule?
A) Br2
B) CH4
C) CO2
D) NH3
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Correct Answer: Option D - NH3
7. What can be concluded if an ion of an element is smaller than an
atom of the same element?
A) The ion is negatively charged because it has fewer electrons than the
atom.
B) The ion is negatively charged because it has more electrons than the
atom.
C) The ion is positively charged because it has fewer electrons than the
atom.
D) The ion is positively charged because it has more electrons than the
atom.
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Correct Answer: Option C - The ion is positively charged because
it has fewer electrons than the atom.
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Ionic radius trend -Cations (positive ions) are always smaller than their
parent atoms and anions (negative ions) are always larger.
8. Which compound contains both ionic and
covalent bonds?
A) Sodium nitrate
B) Ammonia
C) Methane
D) Potassium chloride
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Correct Answer: Option A - Sodium nitrate
9. Which bond has the greatest ionic character?
A) H---N
B) H---F
C) H---Cl
D) H---O
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Correct Answer: Option B - H---F
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H has an electronegativity of 2.1 and F has an electronegativity
of 4.0. Subtract the two values and the difference is 1.9. Ionic
bonds have differences of 1.7 or greater.
11. A solid substance is an excellent conductor of
electricity.The chemical bonds in this substance
are most likely
A) Ionic, because the valence electrons are shared
between atoms
B) Ionic, because the valence electrons are mobile
C) Metallic, because the valence electrons are stationary
D) Metallic, because the valence electrons are mobile
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Correct Answer: Option D - Metallic, because the
valence electrons are mobile
12.The reaction that joins thousands of small,
identical molecules to form one very long
molecule is called:
A) Esterification
B) Polymerization
C) Fermentation
D) Substitution
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Correct Answer: Option B - Polymerization
14. Which statement describes what occurs as two
atoms of bromine combine to become a molecule
of bromine?
A) Energy is absorbed as a bond is formed.
B) Energy is absorbed as a bond is broken.
C) Energy is released as a bond is formed.
D) Energy is released as a bond is broken.
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Correct Answer: Option C - Energy is released as
a bond is formed.
15. An oxygen molecule contains a double bond
because the two atoms of oxygen share a total of
A) 1 electron
B) 3 electrons
C) 2 electrons
D) 4 electrons
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Correct Answer: Option D - 4 electrons
23.To become a calcium ion a calcium atom must:
A) Gain 2 ions
B) Gain 2 protons
C) Lose 2 neutrons
D) Lose 2 electrons
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Correct Answer: Option D - Lose 2 electrons
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An ion is an atom (or group of atoms) that has gained or lost
one or more electrons. Many main group elements gain or lose
electrons such that they have the same number of electrons as
a Noble gas. Calcium, and all of the alkaline earth elements,
lose two electrons. Since electrons are negatively charged, the
loss of electrons gives the resulting ion a positive charge.
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4) NH3 is a polar molecule.
Br2 and CO2 are linear, non-polar molecules. CH4 is a
symmetrical, non-polar molecule
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(3) N is the correct answer.
Electronegativity indicates how strongly an atom of an
element attracts electrons in a covalent bond. See table
S. Also, by memorizing the electronegativity trend of the
periodic table, we can see that electronegativity increases
from bottom to top in a column and from left to right
across a group.
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(2) Is the correct answer.
The definition of a covalent bond is electrons that are
shared between 2 atoms. Hydrogen and Sulfur share
electrons to form a covalent bond. This compound is
similar to Water, where 2 hydrogens share electrons with
one oxygen.
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Correct Answer is 4
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Correct Answer is 2
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Correct Answer is 4
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Correct Answer is 1
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Correct answer: (1) 6
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Correct Answer is 2
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Correct Answer is 4
1. Which sequence of Group 18 elements demonstrates a gradual
decrease in the strength of the Van der Waals forces?
A) Ar, Kr, Ne, Xe
B) Xe, Kr, Ar, Ne
C) Kr, Xe, Ar, Ne
D) Ne, Ar, Kr, Xe
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Correct Answer: Option B - Xe, Kr, Ar, Ne
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The van der Waals force (or van der Waals interaction) is the attractive or
repulsive force between molecules (or between parts of the same
molecule) other than those due to covalent bonds or to the electrostatic
interaction of ions with one another or with neutral molecules. These
forces decrease as the molecule gets smaller and increase as the molecule
increases. Therefore the Van der Waals forces would also be decreasing