unit 2 Flashcards

includes all unit 2 power point information and practice problems (not including math)

1
Q

periodic law original

A

when the elements are arranged in order of increasing atomic mass, certain sets of properties recur periodically

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2
Q

quantum mechanics explains

A

why periodic trends exist

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3
Q

metals preperties

A

solids at room temp
lustrous
good conductors
malleable
ductile
loses electrons to form cations

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4
Q

nonmetals properties

A

gases/brittle solids at room temp
poor conductors
gains electrons to form anions

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5
Q

metalloids

A

poor conductors at room temp
better conductors at high temps

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6
Q

alkali metals properties

A

oxides dissolve in water to form strong basic solutions
corrode in air to dull gray appearance
react vigorously to produce hydrogen
readily form compounds with nonmetals
s1 electron configuration
cations with 1+charge
gets larger as move down group

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7
Q

alkaline earth metals

A

not as reactive as alkali metals
readily form compounds with nonmetals
forms alkaline oxides, some have low solubility in water
s2 electron configuration
cations with +2 charge

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8
Q

halogens properties

A

most reactive nonmetals
F and Cl are gases, Br is liquid, I is solid
exist as diatomic molecules
readily forms compounds with metals and nonmetals
s2p5 electron configuration
gains electrons to have a 1- charge
shares electrons with nonmetals

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9
Q

noble gases

A

unreactive
s2p6 outer electron configuration
stable octet
low reactivity

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10
Q

isoelectronic

A

has same electron configuation

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11
Q

transition metals properties

A

closer to nucleus than representative metals
solid
high melting and boiling points
similarities in properties in a group and across a period
forms cations with multiple charges, forms complex ions
some have characteristic colors

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12
Q

3 factors of periodic trends

A

nuclear charge
number of core electrons
distance of outer electrons from the nucleus

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13
Q

coulomb’s law

A

e = 1/4piCo q1q2/r
e: potential energy
q1q2: charges
r: separation

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14
Q

coulomb’s law

A

strength of interaction increases as charge increases

attractive force between electron and nucleus depends on magnitude of nuclear charge (atomic number) and average distance between nucleus and electron (energy levels)

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15
Q

shielding

A

repulsions cause electron to have net reduced attraction to nucleus

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16
Q

effective nuclear charge

A

amount of attraction electron feels for nucleus

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17
Q

2 types of shielding

A

shielding by core electrons (efficient)
shielding from outer electrons (not efficient)

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18
Q

Zeff =

A

Z (actual charge of nucleus) - S (charge screened by other electrons)

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19
Q

atomic radius

A

1/2 distance between 2 atoms

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20
Q

bond lengths calculation

A

add atomic radii or 2 bonding atoms

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21
Q

cations are _ than their neutral atoms

A

smaller

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22
Q

anions are _ than their original atom

A

larger

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23
Q

ionization energy

A

minimum energy needed to remove an electron

greater IE = harder to remove an electron

increases are electrons are removed, significant jump when an entire energy level is removed

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24
Q

first ionixation energy

A

energy needed to remove the first electron

lowest

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25
Q

electron affinity

A

energy change when atom gains electron

greater attraction between atom + added electron = more negative EA

positive EA = electron won’t attach itself

halogens have most negative

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26
Q

electronegativity

A

ability of an atom in a molecule to attract shared electrons to itself

higher EN = pulls bonded electron closer
smaller atoms = higher EN

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27
Q

spectroscopy

A

studies transmission/reflection of different frequencies of electromagnetic spectrum by a sample of matter

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28
Q

photoelectron spectroscopy

A

core more difficult to remove than valence

uses higher energy light: UV to X-rays

UV studies valence
X-rays studies core

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29
Q

how to do photoelectron spectroscopy

A
  1. beam of x-rays shone on sample (e=hv)
  2. atoms of sample release electrons from any energy level (photoelectric effect)
  3. kinetic energy measured (binding energy = hv - KE)
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30
Q

PES spectrum

A

graph of binding energy (x-axis) and relative number of electrons (y-axis)

height of each peak is proportional to # of electrons of equal energy

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31
Q

UV and visible light spectroscopy

A

white visible light shone on colorful molecules + transition metal ions

doesn’t remove electrons from atom

excites electrons to higher energy state

electrons absorb certain wavelengths and transmit other wavelengths, producing color

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32
Q

reference blank

A

when other compounds in a solution absorbs the same wavelengths as compound being analyzed

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33
Q

beer’s law

A

A = Ebc

A=absorbance
E=molar absorbance
b=path length
c=concentration

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34
Q

calibration curves

A

direct relationship between absorbance and concentration

prepare solutions of known concentrations and analyze at ymax

plot absorbance as function of concentration

used to find the concentration of an unknown solution

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35
Q

meter

A

m
length

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36
Q

kilogram

A

kg
mass

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37
Q

second

A

s
time

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38
Q

Pascal

A

Pa
pressure

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39
Q

kelvin

A

K
temp

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40
Q

liter

A

L
volume

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41
Q

mole

A

mol
amount of substance

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42
Q

SI system

A

dominant system of measurement

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43
Q

giga

A

1,000,000,000

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44
Q

mega

A

1,000,000

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45
Q

kilo

A

1,000

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46
Q

hecto

A

100

47
Q

deka

A

10

48
Q

deci

A

0.1

49
Q

centi

A

0.01

50
Q

milli

A

0.001

51
Q

micro

A

0.000 001

52
Q

nano

A

0.000 000 001

53
Q

pico

A

0.000 000 000 001

54
Q

precision

A

exactness of measurement

55
Q

error =

A

|measured - accepted|/accepted

56
Q

how did Mendeleev organize the PT?

A

ordered by increasing atomic mass

elements with similar properties were in the same column

57
Q

issues with periodic law

A

doesn’t explain why the column pattern exists

58
Q

How did Mendeleev’s periodic table differ from the modern periodic table and how did this affect the wording of the periodic law?

A

Mendeleev: when elements are arranged in order of atomic mass, periodic properties recur

Modern PT is arranged by atomic number (number of protons)

59
Q

Why do elements in the same group have similar chemical properties?

A

They have the same number of valence electrons

60
Q

Which two families contain the most reactive elements? Can you suggest a possible reason for this given their locations in the periodic table?

A

Alkali metals and halogens

Alkali metals lose their outer s1 electron to gain a noble gas configuration

Halogens add an electron to their outer s2 p5 configuration to gain a noble gas configuration

61
Q

periodic trends are due to:

A

strength of attraction between the nucleus and outer electrons

62
Q

3 factors strength of attraction depends on

A

nuclear charge
number of core electrons
distance of outer electrons from nucleus

63
Q

covalent radius

A

1/2 distance between 2 covalently bonded atoms

64
Q

metallic radius

A

1/2 distance between 2 adjacent metal atoms in a metallic crystal

65
Q

nonbonding radius (van der Waal’s radius)

A

1/2 distance between 2 non-bonded atoms that are touching

66
Q

metallic periodic trend

A

increases across a period and down a group

67
Q

atomic radius trend

A

increases down a group

decreases across a period

68
Q

to calculate bond lengths:

A

add atomic radii of two bonding atoms

69
Q

What attractive force is responsible for holding the cloud of electrons in place in atoms?

A

Nuclear attraction

70
Q

What effect would a strengthening of nuclear attraaction have on the size of atoms?

A

Increasing nuclear attraction makes the atom smaller

71
Q

What might cause a strengthening of that force?

A

Increasing the nuclear charge (adding protons)

72
Q

What might contribute to a weakening of that force?

A

Increasing the shielding effect by adding core electrons

73
Q

Why does the quantum mechanical model description of multi-electron atoms make it difficult to define a precise atomic radius?

A

Atoms do not have precise boundaries. Orbitals represent the 90 % probability of finding an
electron in a volume of space

74
Q

When nonbonded atoms come up against one another, what determines how closely the nuclear centers can approach?

A

Repulsion between each of the atom’s outermost electrons

75
Q

Which of the three factors that contribute to atomic size, predominates as we move across a period? What is the result on atomic size?

A

nuclear attraction predominates (no new energy levels added) making the atom smaller

76
Q

Which of the three factors contribute to atomic size predominates as we move down a group? What is the result on atomic size?

A

distance of outer electrons from the nucleus and shielding both increase making the atom larger

77
Q

what happens after cations form from neutral atoms?

A

Electrons are removed from energy levels furthest from nucleus

Electron-electron repulsions decrease

78
Q

what happens when an anion forms from its neutral atom?

A

Electrons are added to energy levels further from the nucleus

Electron-electron repulsions increase

79
Q

isoelectronic series

A

group of ions with the same number of electrons

80
Q

ionic radius periodic trend

A

increases down a group

decreases across a period

81
Q

first ionization energy

A

energy needed to remove the first electron

82
Q

ionization energy _ when successive electrons are removed

A

increases

83
Q

ionization energy trend

A

increases across a period
decreases down a group

84
Q

electron affinity periodic trend

A

decreases down a group

85
Q

electronegativity trend

A

increases across a a period

decreases down a group

86
Q

effective nuclear charge (Zeff) periodic trend

A

increases across a a period

constant down a group

87
Q

distance from nucleus / shielding periodic trend

A

constant across a period

increases down a group

88
Q

t/f: Cations are larger than their corresponding neutral atoms

A

False: cations are smaller than their neutral atoms

89
Q

t/f: Li1+ is smaller than Li

A

True: cations are smaller than their neutral atoms

90
Q

t/f: Cl1- is bigger than I1-

A

False: ionic radius increases down a group for ions with the same charge

91
Q

For isoelectronic ions, how are effective nuclear charge and ionic radius related?

A

They are inversely related-as Zeff increases, ionic radius decreases

92
Q

why is O2- is larger than O

A

Because O2- has gained two more electrons, electron-electron repulsion is increased making the ion bigger than the neutral atom

93
Q

why is S2- is larger than O2

A

ionic radius increases down a group

94
Q

why is S2- is larger than K1+

A

These are an isoelectronic series (3s2 3p6) so increasing atomic number=increasing nuclear charge. S2- has a smaller nuclear charge than K1+ making S2- larger

95
Q

why is K1+ is larger than Ca2+

A

These are an isoelectronic series (3s2 3p6) so increasing atomic number=increasing nuclear charge. K1+- has a smaller nuclear charge than Ca2+ making K1+- larger

96
Q

What is the general relationship between the size of an atom and its first ionization energy?

A

The larger the atom the lower its first IE

97
Q

Explain the difference between ionization energy and electron affinity

A

Ionization energy is the energy change that is required to remove an electron from an atom to form a cation and is usually positive

Electron affinity is the energy change that is required for an atom to gain an electron to form an anion and is usually negative

98
Q

in PES, the number of peaks determines:

A

the number of sublevels in an element

smallest peaks = s sublevels
etc.

highest energy peaks appear farther left (orbitals closest to nucleus)

99
Q

electromagnetic spectrum wavelengths in increasing frequency order

A

radio
microwave
infrared
visible
ultraviolet
x-ray
gamma ray

100
Q

reference blank

A

contains everything that is in the solution that you are trying to measure EXCEPT the thing you are trying to measure

101
Q

precision and uncertainty relation

A

lower uncertainty = higher precision

102
Q

most precise measuring tools

A

1st: biuret
2nd: measuring cylinder

103
Q

are non-zero digits significant?

A

yes

104
Q

are zero’s between non-zero digits significant?

A

yes

105
Q

are leading zero’s significant?

A

no

106
Q

are trailing zero’s significant?

A

only if there is a decimal

107
Q

multiplication and division sign fig rules

A

use the same number of sig figs in the answer as the number with the least amount of sig figs

108
Q

addition and subtraction sig fig rules

A

the result can only have as many decimal places as the number having the least number of decimal places

109
Q

One thousand of the base units for pressure

A

kilopascals (kPa)

110
Q

One tenth of the base unit for the amount of a substance

A

decimole (dmol)

111
Q

One thousandth of the base unit for volume

A

milliliter (mL)

112
Q

1 / (1 x 10^6) of the base unit for time

A

microsecond (us)

113
Q

1 x 10^-1 of the base unit for length

A

decimeter (dm)