Ap Chemistry

Front 1

In a dilute solution of sodium chloride in water, the sodium chloride (NaCl) is the:

Back 1

precipitate.

Sodium Chloride (NaCl) is
also known as salt, common salt, table salt, or halite
and is an ionic compound.

Hint 1

Precipitate means:
an insoluble solid that emerges from a liquid solution.

The emergence of the insoluble solid from solution is called precipitation.

Precipitates can form when two soluble salts react in solution to form one or more insoluble products.
The insoluble product separates from the liquid and is called a precipitate.

Precipitates can also form when the temperature of a solution is lowered.
The lower temperature reduces the solubility of a salt,
resulting in its precipitation as a solid.

Front 2

Solids exhibiting this kind of bonding are excellent conductors of heat.

Back 2

metallic bonding

Hint 2

In metallic bonding, nuclei are surrounded
by a sea of mobile electrons.

The electrons' freedom to move
allows them to conduct heat and electricity.

Front 3

This kind of bonding is the reason that water is more dense than ice.

Back 3

hydrogen bonding

Hint 3

When ice forms, the hydrogen bonds
join the molecules in a lattice structure,
which forces them to remain farther apart than they had been in the liquid form.

Because the molecules are farther apart in the solid than in the liquid,
the solid (ice) is less dense than the liquid.

Front 4

This kind of bonding exists between atoms with very different electronegativities.

Back 4

ioni bonding

Hint 4

Electronegativity is a measure of how much pull an atom
exerts on another atom's electrons.

If the difference in electronegativites is large enough (greater than 1.7),
then te more electronegative atom will simply take an electron away from the other atom.

The two atoms will then be held together by electrostatic attraction
(the atom that has gained an electron becomes negative and
the atom that has lost an electron becomes positive.)

That's an ionic bond.

Front 5

The stability exhibited by diamonds is due to this type of bonding.

Back 5

network covalent bonding

Hint 5

The carbon atoms in diamond are held together by a network of covalent bonds.

The carbon atoms form sp3 hybrid orbitals,
resulting in a tetrhedral structure which is very stable and
has no simple breaking points.

Front 6

Intermolecular attractions resulting from the constant motion
of electrons and thecreation of instantaneous dipoles and induced dipoles is known as:

Back 6

London dispersion forces.

Hint 6

London dispersion forces act between atoms and molecules but
are the only intermolecular forces acting among the noble-gas aoms and nonpolar molecules.

Front 7

NaCl undergoes what type of bonding?

Back 7

ionic bonding

Hint 7

NaCl iscomposed of two elements of very different electronegativities,
so Na gives up an electron to Cl
and the two are held together by electrostatic attraction in an ionic bond.

Front 8

N2 contains two of what type of bond?

Back 8

pi bonds

Hint 8

N2 contains a triple bond,
so it has one sigma bond and two pi bonds.

Front 9

NH3 undergoes what type of bonding?

Back 9

hydrogen bonding

Hint 9

Hydrogen bonding occurs between hydrogen atoms of one molecule and electronegative elements (F,O,N) of another molecule.

So in ammonia, hydrogens from one ammonia molecule will form bonds with nitrogens from another ammonia molecule.

Front 10

The central atom in th BF3 molecule forms what type of orbitals?

Back 10

sp2 hybrid orbitals

Hint 10

In BF3, boron forms three bonds with fluorine atoms and has no unbonded valence electrons,
so it must form sp2 hybrid orbitals.

Front 11

What type of structure does CF4 have?

Back 11

a tetrahedral structure

Hint 11

CF4 forms a tetrahedral structure.

The central carbon atom is hybridized sp3.

Front 12

CO2 has what type of structure?

Back 12

a linear structure

Hint 12

CO2 forms a linear structure.

The central carbon atom is sp hybridized.

Front 13

A liquid whose molecules are held together by which type of forces would be expected to have the lowest boiling point?

Back 13

London dispersing forces

Hint 13

A liquid with a low boiling point must be held together by weak bonds.

London dispersion forces are the weakest kind of intermolecular force.

Front 14

List an example of hydrogen bonding that would be commonly seen.

Back 14

H2O

Hint 14

Hydrogen bonding specifically describes the attraction experienced by a hydrogen atom in one molecule to an extremely electronegative element (F,O,N) in another molecule.

So, in water, a hydrogen atom in one water molecule will be attracted to an oxygen atom in another molecule.

Front 15

Which of the following species does NOT have a tetrahedral structure? (CH4, NH4, SF4, AlCl4, CBr4)

Back 15

SF4

Hint 15

SF4 has 34 valence electrons distrubuted in the Lewis structure and shape.

Lewis structure:
a formula in which atomic symbols represent nuclei and inner-shell electrons,
dots and dashes represent electron pairs in covalent bonds,
and dots represent unshared electrons.

Front 16

Which form of orbital hybridization can form molecules
with shapes that are either trigonal pyramidal or tetrahedral?

Back 16

sp3

Hint 16

Sp3 hybrid orbitals take a tetrahedral shape if the central atom has no unshared electron pairs (CH4, for instance),

If the central atom has one unshared electron pair, the molecule takes the trigonal pyramid shape (NH3, for instance).

Front 17

The 6 carbon atoms in a benzene molecule are shown in different resonance forms as 3 single bonds and 2 double bonds.

If the length of a single carbon-carbon bond is 154 pm and the length of a double carbon-carbond bond is 133 pm,
what length would be expected for the carbon-carbon bonds in benzene?

Back 17

140 pm

Hint 17

Resonance is used to describe a situation that lies between single and double bonds,
so the bond length would also be expected to be in-between that of single and double bonds.

Front 18

In which of the following species does the central atom NOT form sp2 hybrid orbitals?
(SO2, BF3, NO3-, SO3, PCl3)

Back 18

PCl3`

Hint 18

PCl3 forms sp3 orbitals, instead.

Front 19

A molecule whose central atom has d2sp3 hybridization can have which shape?

Back 19

square pyramidal or square planar

Hint 19

A molecule with d2sp3 hybridization has octahedral structure if the cetral atom has no unbonded electrons (SF6, for instance).

Central atom with one unbonded electron pair = square pyramidal.

Central atom with 2 unbonded electron pairs = square planar.

Front 20

Explain why the following list of species is listed in order of increasing boiling point.
H2, N2, NH3

Back 20

H2 experiences only van der Waals forces and has the lowest boiling point.

N2 also experiences only van der Waals forces, but it is larger than H2
and has more electrons, so it has stronger van der Waals interactions with other molecules.

NH3 is polar and undergoes hydrogen bonding, so it has the strongest intermolecular interactions and the highest boiling point.`

Hint 20

van der Waals:

proposed that real gases deviate from the behavior expected of an ideal gas because:
1. particles of real gases occupy space.
2. particles of real gases exert attractive forces on each other.

Front 21

(A) 0.1 M HCl
(B) 0.1 M NaCl
(C) 0.1 M HC2H3O2
(D) 0.1 M CH3OH
(E) 0.1 M KOH

Is weakly acidic.

Back 21

(C) 0.1 M HC2H3O2

Front 22

(A) 0.1 M HCl
(B) 0.1 M NaCl
(C) 0.1 M HC2H3O2
(D) 0.1 M CH3OH
(E) 0.1 M KOH

Has the highest pH.

Back 22

(E) 0.1 M KOH

Front 23

(A) 0.1 M HCl
(B) 0.1 M NaCl
(C) 0.1 M HC2H3O2
(D) 0.1 M CH3OH
(E) 0.1 M KOH

Reacts with an equal volume of 0.05 M Ba(OH)2
to form a solution with pH = 7.

Back 23

(A) 0.1 M HCl

Front 24

(A) X+
(B) X2+
(C) X3+
(D) XO3 2–
(E) XO4 2–

A type of ion found in sodium acetate.

Back 24

(A) X+

Front 25

(A) X+
(B) X2+
(C) X3+
(D) XO3 2–
(E) XO4 2–

A type of ion found in aluminum oxide.

Back 25

(C) X3+

Front 26

(A) X+
(B) X2+
(C) X3+
(D) XO3 2–
(E) XO4 2–

A type of ion found in potassium phosphate.

Back 26

(A) X+

Front 27

What is a chemical bond?

Back 27

A link between atoms that results from the mutual attraction of their nuclei for electrons.

Front 28

Upon what basis are the various chemical bonds classified?

Back 28

By the way in which valence electrons are distributed around the nuclei of the combined atoms.

Front 29

Among main group elements, what ion formation tendencies are generally observed?

Back 29

Metals tend to LOSE electrons to form positive ions (cations).

Nonmetals tend to GAIN electrons to form negative ions (anions).

Front 30

Identify and define the two major types of chemical bonding.

Back 30

IONIC BOND: a chemical bond resulting from electrostatic attraction between positive and negative ions.

COVALENT BOND: a chemical bond resulting from the sharing of electrons between two atoms.

Front 31

What is the relationship between electronegativity and the ionic character of a chemical bond?

Back 31

The more two atoms differ in electronegativity, the more ionic the bond between them.

In other words, the electrons spend more time close to the bonded atom that attracts them more strongly and hence cause that atom to partially resemble an anion and the other atom to resemble a cation.

Front 32

What is the meaning of the term "polar", as applied to chemical bonding?

Back 32

A chemical bond between atoms in which an UNEVEN distribution of charge exists.

Front 33

Distinguish between polar and nonpolar covalent bonds.

Back 33

POLAR COVALENT BOND: the united atoms have an UNEQUAL attraction for the shared electrons, resulting in a UNEVEN distribution of charge.

NONPOLAR COVALENT BOND: the bonding electrons are EQUALLY shared by the bonded atoms, with a resulting BALANCED distrubution of electrical charge.

Front 34

In general, what determines whether atoms will form chemical bonds?

Back 34

If the atoms' potential energy is lowered by the change, two atoms will form a chemical bond.

Front 35

What energy change is usually associated with bond formation?

Back 35

a decrease

Front 36

What determines bond length?

Back 36

Whether attraction outweighs repulsion between electrons and nuclei of two atoms.

Front 37

How are bond lengths and bond energies related?

Back 37

Bond energies become larger as bond lengths become shorter.

Front 38

Describe the general location of the electrons in a covalent bond.

Back 38

They are free to move around in either of the orbitals, but spend more time in the space between the two nuclei than elsewhere.

Hint 38

Thus, in the region of orbital overlap, there is an increased electron density.

The attraction of the nuclei to the high electron density in this region holds the two atoms together.

Front 39

As applied to covalent bonding, what is meant by an UNSHARED or LONE PAIR of electrons?

Back 39

A pair of electrons that is not involved in bonding, but instead belongs exclusively to one atom.

Front 40

Determine the number of valence electrons contained in an atom of: H (hydrogen).

Back 40

one

Hint 40

1s

Front 41

Determine the number of valence electrons contained in an atom of: F (fluorine).

Back 41

seven

Hint 41

The Halogens (Group 17) has seven valence electrons.

Front 42

Determine the number of valence electrons contained in an atom of: O (oxygen).

Back 42

six

Hint 42

Group 16 has six valence electrons.

Front 43

Determine the number of valence electrons contained in an atom of: N (neon).

Back 43

eight

Hint 43

The least reactive of all the elements because their outer shell is complete with an octet (8 electrons).

Front 44

When drawing Lewis structures, how do you determine the central atom of the arrangement?

Back 44

Usually, the most electropositive atom is central.

Hint 44

Hydrogen and the Halogens are very rarely, if ever, central atoms.

Carbon, silicon, nitrogen, phosphorus, oxygen, and sulfur are always good candidates, because they form more than one covalent bond in filling their valence energy level

In the case of water, H2O, oxygen is the central element and the hydrogen atoms are both bonded to it.

Front 45

Distinguish among single-, double-, and triple-covalent bonds by defining each and providing an illustration of each type.

Back 45

SINGLE-COVALENT BOND: a covalent bond produced by the sharing of one pair of electrons between two atoms. i.e. ?

DOUBLE-COVALENT BOND: a covalent bond between two atoms produced by the sharing of two pairs of electrons. i.e. ?

TRIPLE-COVALENT BOND: a covalent bond produced by the sharing of three pairs of electrons between two atoms. i.e. ?