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Chemistry Flashcards

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1
Q

What is the mass # of an element?

A

The protons and neutrons together (nucleus). Top number in atomic notation.

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2
Q

What is the atomic # of an element?

A

The protons in an element. It is unique to EACH element. The bottom number in atomic notation.

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3
Q

Define an isotope.

A

2 or more atoms of the same elements that contain different number of NEUTRONS

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4
Q

Describe metals.

A
  • Tend to loose electrons to form (+) ions
  • ductile (easily stretched)
  • malleable
  • thermal and electrically conductive
  • luster
  • solid @ room temp
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5
Q

Describe nonmetals.

A
  • covalent bonds w. one another
  • lower melting points (than metals)
  • form anions
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6
Q

Describe alkali metals.

A
  • soft metallic solids
  • low density
  • low melting point
  • highly reactive
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7
Q

Describe alkaline earth metals (in comparison with alkali metals)

A
  • harder, denser
  • high melting point
  • less reactive
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8
Q

In which direction does atomic radius of an element increase?

A

Down a group and to the left of the periodic table

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9
Q

Define Zeff (effective nuclear charge) ? in regards to ‘shielding’ how are they related?

A
  • The amount of charge felt by the most recently added electron.
  • Zeff and shielding are inversely proportional
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10
Q

In which direction does ionization energy of an element increase?

A

to the right of the periodic table and up a group

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11
Q

Which is greater…the first or second ionization energy?

A

The second one

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12
Q

In which direction does electronegativity of an element increase?

A

to the right of the periodic table and up a group

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13
Q

What is an ionic bond? A polar covalent bond? a non polar covalent bond?

A

ionic: atoms with large differences in electronegativity
polar covalent: atoms with moderate differences in electronegativity
non polar covalent: atoms with minor differences in electronegativity

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14
Q

In which direction does electron affinity of an element increase?

A

to the right of the periodic table and up a group

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15
Q

Define the Pauli Exclusion Principle.

A

No 2 electrons in same atom can have the same 4 quantum numbers

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16
Q

What is the Heinsburg uncertainty principle?

A

The inherent uncertainty in the product of the POSITION of a particle and its MOMENTUM

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17
Q

Define the Aufbau principle.

A

Each new proton added to create new element, that new electron will occupy the lowest energy level available

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18
Q

What is Hund’s rule?

A

Electrons will not fill any orbital in same subshell until all orbitals in subshell contain 1 electron, then when 2 electrons in same orbital will have opposite spins

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19
Q

What occurs in ALPHA decay?

A
  • loss of a Helium nucleus (4 units of mass and 2 protons)

- emits an ‘alpha’ particle

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20
Q

What occurs during BETA decay - positron emission?

A
  • A proton becomes a neutron
  • emits a position (and neutrino)
  • loose one atomic # - so move to the left
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21
Q

What occurs during BETA decay - electron capture?

A
  • electron and proton merge together and form a neutron
  • emits a neutrino
  • loose one atomic # - so move to the left
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22
Q

In an sp hybridized molecule, what is the bond length and shape?

A
  • 180 degrees

- linear

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23
Q

In an sp2 hybridized molecule, what is the bond length and shape?

A
  • 120 degrees

- trigonal planar

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24
Q

In an sp3 hybridized molecule, what is the bond length and shape?

A
  • 109.5 degrees

- tetrahedral trigonal, pyramidal, bent

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25
What makes a molecule aromatic?
cyclic, planar and follow huckels rule: 4n+2 (with n being the number of pi bonds, or lone pairs)
26
Nucleophillic functional groups are....?
- Have a partial negative charge and seek positive - DONATE electrons and 'attack' others - aka lewis bases
27
Electrophillic functional groups are...?
- Have partial positive charge and seek negative - ACCEPT electrons and get 'attacked' by others - aka lewis acids
28
Define a structural isomer.
Molecules with the SAME formula, but DIFFERENT connectivity,
29
What are conformational isomers?
(not true isomers) have DIFFERENT spatial orientations of same molecule
30
Differentiate enantiomers and diastereomers
E: mirror images, are chiral molecules (R or S) D: NOT mirror images, have a MIX of R or S carbons
31
In regards to the rotation of polarized light, 'D' means? and 'L' means?
D= positive | L=negative
32
What is a meso compound?
a molecule with multiple chiral centres, but optically inactive (have plane of symmetry THROUGH molecule) -are called achiral
33
What are the only things that affect 'k', the rate constant?
Pressure, catalysts and temperature
34
What is the first law of thermodynamics?
The total energy of a system and surroundings are conserved
35
What is the second law of thermodynamics?
The entropy of an isolated system will never decrease
36
When is a reaction ALWAYS spontaneous in regards to Gibbs free energy?
When 'H' is ( -) and 'S' is ( + )
37
When is a reaction ALWAYS non-spontaneous in regards to Gibbs free energy?
When 'H' is ( + ) and 'S' is ( - )
38
What is the kinetic molecular theory (for ideal gases)?
1. gas molecules have NO size 2. No attractive/repulsive forces on one another 3. Completely elastic collisions 4. Avg. kinetic energy directly proportional to temp.
39
What is heat capacity?
the added energy required to increase the temp. of a given substance by one Kelvin
40
If something has a greater heat capacity, that means...?
Can absorb more heat with LESS of a temperature change. Have more intermolecular bonds in a molecule, and bond stretching can occur
41
1 cal =_____J
4.185 J
42
What does a coffee cup calorimeter entail?
a constant PRESSURE, therefore open at the top to atmospheric pressure. Measures the heat of reaction (H) since with constant P, q=(delta)H. Can calculate q=mc(delta)T
43
What does a bomb calorimeter entail?
a constant VOLUME, therefore thermally insulated, rigid container. Measures the internal energy, with heat capacity of the machine, can calculate q=C(delta)T
44
What is the difference between covalent bonds and ionic bonds?
Covalent: bond between 2 NON METALS with similar electronegativities that share electrons. Ionic: bond between a non metal and a metal that are oppositely charged and exchange electrons
45
What is an induced dipole? How is it different from dipole-dipole interactions?
When a polar molecule causes a non-polar molecule to 'flip' to being polar, creating a spontaneous and brief dipole moment.
46
What is the relationship between 'K' the equilibrium constant, and 'Q' the reaction quotient?
'K; does NOT change unless temperature change, 'Q' does change. - If K=Q, in equilibrium - If K < Q, reaction favours products (too much reactants) - If K > Q, reaction favours reactants (too much products)
47
What does (delta)H tell us?
The enthalpy of a reaction, whether it is exothermic (-) or endothermic (+)
48
What does (delta)S tell us?
The entropy of the system. Will always be a positive number
49
In solution formation, what does a (+) enthalpy of solution mean? A (-) one?
The (+) enthalpy of solution means that weaker intermolecular bonds have formed, a (-) one means that stronger intermolecular bonds have formed (spontaneous)
50
When does a compound evaporate?
When the vapour pressure of its liquid phase is GREATER than its gas phase
51
Is vapour pressure a function of temperature?
yes!
52
What factors affect solubility?
- Pressure affects solubility of GAS (via Raoults Pv=XPa) - Temperature increases, solubility increases - pH affects solubility too
53
In a galvanic cell is the anode the (+) or the (-)?
The anode is the (-) electrode!!!
54
How does an electrolyte cell work?
It forces the redox reactions in the opposite directions (i.e. the E = (-) )
55
A lewis acid ________ pair of electrons.
a lewis acid ACCEPTS a pair of electrons
56
A lewis base _______ pair of electrons
a lewis bas DONATES a pair of electrons
57
An acid that holds onto their H+'s really tight are a strong/weak acid?
a WEAK acid
58
The factors that determine whether a compound is an acid?
- strength of a bond holding H+ to the molecule - polarity of a bond - stability of conjugate base *** most important
59
in a molecule, as you increase O2's you increase the strength of _____?
acidity!
60
How is pH related to H+?
pH = -log[H+]
61
How are Ka, pKa and acidity related?
As you INCREASE Ka, you DECREASE pKa, and INCREASE acidity
62
At the equivalence point, what happens?
The titrant (the acid or base) has equal parts of solution (acid or base)
63
What is the henderson-hasselback equation?
pH = pKa + log (A/HA)
64
When doing titrations, the indicator should be....?
pick an indicator with as close pKa as possible to pH of titrations equivalence point
65
When making buffers, which acid to pick?
Pick an acid with close pKa to pH you want to buffer solution. Then Mix a weak acid with the salt of its conjugate base

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