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Chemistry > Test 2 (8, 10) > Flashcards

Test 2 (8, 10) Flashcards

(48 cards)

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1
Q

What is a chemical bond? What is bond energy?

A

A force that holds 2 or more atoms together. The energy required to break a bond

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2
Q

What is an ionic bond?

A

Electrostatic attraction between oppositely charged ions. A metal reacts with a nonmetal.

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3
Q

What is lattice energy? What type of reaction is the formation of a lattice? What is the trend?

A

The energy required to separate a mole of ionic compound into its gaseous ions. The formation of a lattice is exothermic. Lattice energy increases as the charge increases or when the radius decreases. (more charge/smaller ions = more energy to break lattice).

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4
Q

What is covalent bonding?

A

a type of bond where e- is shared. Usually between two nonmetals

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5
Q

What is a polar-covalent bond?

A

a covalent bond in which e- are not shared equally because one atom attracts e- more (electronegativity) than the other atom.

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6
Q

What is electronegativity? Trends? Most electronegative element? Who developed a scale for this?

A

tendency of an atom to pull shared e- to itself. Increases down a period decreases down a group; this is the same as electron affinity. The most electronegative element is fluorine. Linus Pauling.

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7
Q

Know how to draw Lewis Structures

A

:)

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8
Q

Octet Rule? Exceptions?

A

An atom needs 8 valence electrons to be stable. Most 3rd row and below elements are an exception and can have more, as well as Be (4e-) and B (6e-).

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9
Q

What are dipoles? Dipole moment? What happens to some molecules with polar bonds? What 3 geometries exemplify this?

A

Have a positive center and a negative center. The dipole moment is a property of a molecule whose charge distribution can be represented by a center of positive charge and a center of negative charge. Some molecules may have polar bonds, but no dipole moment. POLARITY DEPENDS ON SHAPE TOO. Linear molecules, Trigonal Planar, Tetrahedral.

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10
Q

2 bonding pairs, and 0 nonbonding pairs?

A

linear, 180, sp, (know image)

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11
Q

3 bonding pairs, and 0 nonbonding

A

trigonal planar, 120, sp2 ,(know image)

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12
Q

3 bonding pairs, and 1 nonbonding

A

pyramidal, 107, sp3, (know image)

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13
Q

3 bonding pairs and 2 nonbonding

A

T-Shaped, 90/180, sp3d, (know image)

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14
Q

4 bonding pairs and 0 nonbonding

A

tetrahedral, 109.5, sp3,(know image)

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15
Q

4 bonding pairs and 1 nonbonding

A

irregular/distorted tetrahedral, >90, sp3d,(know image)

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16
Q

4 bonding pairs and 2 nonbonding

A

square planar, 90/180, sp3d2,(know image)

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17
Q

5 bonding pairs and 0 nonbonding

A

trigonal bipyramidal, 90/120, sp3d,(know image)

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18
Q

5 bonding pairs and 1 nonbonding

A

square pyramidal, 90/180, sp3d2,(know image)

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19
Q

6 bonding pairs and 0 nonbonding

A

octahedral, 90/180, sp3d2,(know image)

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20
Q

What is resonance? Is it real? What differs? What is the actual structure?

Study These Flashcards
A

Resonance is when more than 1 lewis structure is possible. Resonance structures are NOT real. The placement of the pi bonds differ (double and triple bonds). The actual structure is a combination of all resonance

21
Q

What is Formal charge? How do we apply this to resonsnace?

Study These Flashcards
A

Charge on atoms in a molecule as if all atoms have the same electronegativity. Does not represent real charges. To calculate, all unshared e- are assigned, and half of the bonding e- are assigned to their own atoms. Formal charge = number of e in atom - number of e- assignment to atom in bonding and nonbonding pairs. Most stable resonance structures are ones with formal charges closes to 0, with any negative charges on more electronegative atoms. The sum of all formal charges must be 0.

22
Q

Know how to do resonance structures w/ lewis structures.

Study These Flashcards
A

examples in notebook!

23
Q

What are the molecules containing 2 or more central atoms and what are the central atoms?

Study These Flashcards
A

CH3OOH (central carbon and oxygen), CH3COOH (2 central carbons, left one with 3 H and another with an O and OH), and CH3CCH (3 central carbons, one with 3 Hs and on the other end has 1H.

24
Q

What is an intramolecular force? Intermolecular force?

Study These Flashcards
A

Bonding forces within a molecule (such as covalent bonds). Weaker bonding forces between the molecule, like hydrogen bonds.

25
What is a gas? Liquid? Solid?
a gas is a collection of widely separated molecules in chaotic motion. It has weak attractive forces. A liquid is more dense and less compressible than gas. It has strong enough intermolecular forces that keep the molecules close, but not from moving past each other. Solids are not compressible and highly ordered. The intermolecular forces are strong enough to lock the atoms in place.
26
What are the Types of intermolecular forces? What else are they known as? How strong are they compared to intramolecular forces?
Dipole-Dipole forces, Hydrogen bonds, and London dispersion forces. They are also known as Van der Waals forces. These forces are <15% as strong as covalent/ionic bonds.
27
What are dipole-dipole forces? what are the trends?
Neutral polar molecules attract one another when the + end of one is near the - end of another. Smaller molecules have higher Dipole-Dipole forces. When molecules have similar mass and size, higher polarity increases the strength of these forces.
28
What are London Dispersion Forces (LDFs)? What influences it?
neutral nonpolar molecules can attract one another due to the instantaneous unequal distribution of electrons. The e- of one atom can influence another near it. A temporary dipole on one atom can induce a similar dipole on an adjacent atom. This causes them to attract one another. THIS IS INSTANTANEOUS. Larger molecules experience higher LDFs due to having more electrons! Larger surface area have larger LDFs. The shape of the molecule also influences this.
29
What is polarizability?
The ease with which the charge distribution within a molecule can be distorted to induce a temporary dipole.
30
What is hydrogen bonding? How strong is it compared to other 2 intermolecular forces? What are the 3 atoms hydrogen bonds occur with?
An attraction between the H atom in a polar bond that is bonded to an electronegative atom and the lone pairs of electrons on another atom. They are stronger than the other 2 bonds. Happens when hydrogen is covalently bonded to FON (fluorine, oxygen, nitrogen).
31
What is evaporation?
molecules of a liquid can escape liquids surface and form a gas
32
What is condensation?
Vapor molecules form a liquid
33
What is vapor pressure?
Pressure exerted by a vapor in equilibrium w liquid or solid phases (where evaporation rate = condensation rate).
34
Practice: Identify the predominant forces in the solids of these atoms! Ar, HCl, HF, CaCl2, CH4, CO, NaNO3.
Ar: LDF (no polarity and H); HCl: D-D and LDFs (polar); HF : H+ and LDF (H bonded to F); CaCl2: ionic (metal); CH4 : LDFs (no polarity); CO: D-D, LDF (polar); NaNO3 : ionic (metal)
35
How do you measure vapor pressure?
Use a barometer w/ a standard value and subtract the differences between the values. (Barometer with nothing - barometer with gas)
36
What does a high Vapor Pressure mean? How does it react to temp increases?
It evaporates quickly and is volatile. VP will increase w/ temp.
37
Boiling points and freezing points are directly related to?
strength of intermolecular forces.
38
What are phase changes?
conversions of a substance from one state of matter to another. Melting <--> freezing, Sublimation <--> Deposition, Vaporization <--> condensation. Every phase change is accompanied by a change in energy.
39
What is normal melting point? Heat of fusion?
Normal melting point is the point where temp does not change until all solid is converted to liquid. For water, this is 0C. Heat of fusion is the energy required to convert all solid to liquid once normal melting point is hit.
40
What is the normal boiling point? The heat of vaporization?
The temperature in which temp remains constant until all liquid becomes vapor. The heat of vaporization is the energy required for this to happen.
41
Why is heat of vaporization energy required larger than heat of fusion energy?
All the intermolecular forces must be broken!
42
What is heat of sublimation? how is it calculated?
the energy required to go straight from solid directly to vapor. Hfus + Hvap
43
What are the reverses of the heating processes?
Heat of condensation (is just negative heat of heat of vaporization.) Heat of deposition (is just negative of heat of sublimation.) Heat of freezing (is just negative of heat of fusion).
44
What is a heating curve?
A graph of temperature of system vs. heat added (x axis). Know what it looks like!!!!
45
What is specific heat? Equation for it?
Amount of heat needed to raise temperature of a substance. Q = mS(change in temp). Energy = mass*specific heat*change in temperature. Specific heat is provided, except for H2O.
46
What are the specific heats for the 3 states of matter for H2O? What is the Heat of fusion? Heat of vaporization?
Ice: 2.03J/g per C; Water: 4.18J/g per C; Steam: 2.02J/g per C Hfus: 6.02 kJ/mol Hvap: 40.6kJ/mol
47
Know how to calculate the energy required for a substance going from one temp to another using the specific heats and heats of fusion and vaporization!
:)
48
What are the types of solids? What are the interactions? Properties? Type of molcules?
Ionic- electrostatic; high melting point/brittle/hard; ionic molecules Molecular - intermolecular forces; low mp/nonconducting. made of small symmetrical molecules such as H2, N2, F2, H2O, etc. metallic - metallic bonding (sea of e-); varies/conductive; made of metals covalent network - covalent bonding; high mp, hard, nonconductive; made of molecules than can chain covalent bonds like Carbon in diamonds

Chemistry (10 decks)

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