AP Chem - Chapter 7 - Electrons and Periodicity Flashcards Preview

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Flashcards in AP Chem - Chapter 7 - Electrons and Periodicity Deck (69)
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1
Q

what is wavelength

A

symbol = lambda

distance between 2 consecutive peaks or troughs in a wave

2
Q

what is frequency

A

symbol = nu

number of waves (cycles per second) that pass a given point in space

3
Q

do all types of electromagnetic radiation travel the same speed

A

yes

4
Q

how fast do all types of electromagnetic radiation travel

A

at the speed of light

5
Q

what is the relationship between wavelength and frequency

A

inversely proportional

6
Q

what is the relationship between wavelength and energy

A

inversely proportional

7
Q

what is the relationship between frequency and energy

A

directly proportional

8
Q

what does it mean that energy is quantized

A

it can only occur in discrete units called quanta

9
Q

what do we call atoms that have absorbed more energy

A

excited

10
Q

what happens when atoms are excited

A

they contain excess energy which they release by emitting light of various wavelengths to produce an emission spectrum

11
Q

what is the ground state

A

lowest possible energy state

12
Q

as the electron is brought closer to the nucleus, energy is

A

removed from the system

13
Q

what is the Heisenberg uncertainty principle

A

we cannot know both the position and the momentum of an electron simultaneously

14
Q

what is an orbital

A

a specific wave function

15
Q

what is the principal quantum number (n)

A

has positive integral values (1, 2, 3…)
relates to the size and energy of the orbital
often called energy level or shell

16
Q

what does a bigger n (principal quantum number) mean

A

farther from nucleus and electrons are less tightly held and increase in energy

17
Q

what is the angular momentum quantum number (l)

A
has integral values from 0 (n-1 for each n value) related to the shape of atomic orbitals
l = 0 S shape
l = 1 P shape
l = 2 D shape
l = 3 F shape
18
Q

what is the magnetic quantum number (m sub l)

A

has integral values from l to -l

relates the the kind of orbital and how many there are of it

19
Q

what is a node

A

an area of an orbital having zero electron probability

20
Q

what shape are s orbitals

A

sphere

21
Q

how many orbitals does s have

A

1

22
Q

what shape are p orbitals

A

infinity shape

23
Q

how many orbitals does p have

A

3

24
Q

how many orbitals does d have

A

5

25
Q

how many orbitals does f have

A

7

26
Q

how is the hydrogen electron viewed in the quantum mechanical model

A

as a standing wave, which leads us to a series of wave functions (orbitals) that describe the possible energies and spatial distributions available to the electron

27
Q

what is the electron spin quantum number

A

electrons can either spin clockwise or counter clockwise

represents one of the 2 possible values for the electron spin; either 1/2 or -1/2

28
Q

can any 2 electrons in an atom have the same set of 4 quantum numbers?

A

no

29
Q

what does degenerate mean

A

having the same energy

30
Q

if all 2p orbitals are empty, why does it not matter which orbital the electron goes to

A

because they all have the same energy (are degenerate)

31
Q

what is Hund’s rule

A

The lowest energy configuration for an atom is the one having the maximum number of unpaired electrons allowed by the Pauli principle in a particular set of degenerate orbitals

32
Q

what are the core electrons

A

the inner electrons

33
Q

what are valence electrons

A

the electrons in the outermost principal quantum level of an atom

34
Q

what is the electron configuration for chromium

A

4s1 3d5

35
Q

what is the electron configuration for copper

A

4s1 3d10

36
Q

use effective nuclear charge (Zeff) to justify trends

A

across a period

37
Q

use increased distance (greater value of n) to justify trends -

A

down a group

38
Q

what are the 4 arguments for justifying periodic trends

A
  1. effective nuclear charge
  2. Distance
  3. Shielding
  4. Electron/electron repulsions
39
Q

what is effective nuclear charge

A

essentially equal to the group number
the higher the Zeff, the more positive the nucleus, the more attractive force emanating from the nucleus drawing electrons in or holding them in place

40
Q

what is distance

A

attractive forces dissipate w increased distance

distant electrons are held loosely and thus are more easily removed

41
Q

what is shielding

A

electrons in the “core” effectively shield the nucleus’ attractive force the the valence electrons
use this ONLY when going UP AND DOWN the table NOT ACROSS

42
Q

what is minimize electron/electron repulsions

A

puts the atom at a lower energy state, which is more stable

typically good for explaining weird exceptions

43
Q

what is the trend for atomic radius

A

increases going down the table, decreases going across the table

44
Q

what is the trend for ionization energy

A

decreases going down the table, increases going across

45
Q

what is atomic radius

A

refers to the distance between the nucleus and the outer edge of the electron cloud

46
Q

what is atomic radius influenced by

A

nuclear pull and number of energy levels

47
Q

why does atomic radius decrease moving across the table

A
Zeff increases (more protons for the same number of energy levels) as we move across the table
nucleus has a greater positive charge so the entire electron cloud is more strongly and "shrinks" (until the point at which electron/electron repulsions overcome the nuclear attractions and stop the contraction of the electron cloud
48
Q

why does atomic radius increase going down the table

A

the principal level (n) determines the size of an atom, so you add another principal level and the atoms get a much larger radii
increased number of energy levels (n) increases the distance over which the nucleus must pull and therefore reduces the attraction for electrons
full energy levels provide some shielding between the nucleus and the valence electrons

49
Q

What is ionization energy

A

the energy needed to remove an electron from a gaseous atom or ion, i.e. an isolated one, not part of a solid, liquid, or a molecule. Always endothermic
removing each subsequent electron requires more energy

50
Q

why does ionization energy increase across the table

A

Increasing Zeff increases the attraction of the nucleus and therefore holds the electrons more tightly

51
Q

What exceptions exist in regards to ionization energy

A

1) a drop in IE occurs between groups II and III because the p electrons do not penetrate the nuclear region as greatly as s electrons do and are therefore not tightly held
2) a drop in IE occurs between groups 5 and 6 because the increased repulsion created by the first pairing of electrons outweighs the increase in Zeff and thus less energy is required to remove the electron

52
Q

why does ionization energy decrease down the table

A

increased number of energy levels (n) increases the distance over which the nucleus must pull and therefore reduces the attraction for electrons
full energy levels provide some shielding between the nucleus and valence electrons

53
Q

What is electron affinity

A

involves the addition of an electron to a gaseous atom or ion (can be exo or endothermic)

54
Q

what is the trend for electron affinity

A

decreases as you go down the table (becomes less negative, giving off less energy)
increases across the table (becomes more negative, giving off more energy)

55
Q

why does electron affinity decrease as you go down the table

A

increased distance from the nucleus w each increasing principal E level. The nucleus is farther from the valence level and more shielded

56
Q

why does electron affinity increase as you go across the table

A

increasing Zeff more strongly attracts the electrons

57
Q

what are the exceptions with electron affinity

A

F and Cl bc they only need 1 more electron to achieve noble gas configuration so they will readily accept it
K and Na but for the opposite reason

58
Q

what is electronegativity

A

the ability of an atom IN A MOLECULE to attract shared electrons to itself

59
Q

what is the trend for electronegativity

A

increases across table and decreases down table

60
Q

why does electronegativity increase across the table

A

as Zeff increases, the nucleus becomes more strongly attracted to the electrons

61
Q

why does electronegativity decrease down the table

A

increased number of energy levels (n) increases the distance over which the nucleus must pull and therefore reduces the attraction for electrons
Full energy levels provide some shielding between the nucleus and valence electrons

62
Q

what is ionic radius

A

the distance from the nucleus to the outer edge of the electron cloud in a charged ion

63
Q

what is the ionic radii trend

A

increase going down the table
cations shrink
anions expand

64
Q

why do cations shrink

A

cations result from the loss of valence electrons so in many cases this means the farthest electrons are now in a smaller principal energy level than the original neutral atom
as electrons are lost, the ratio of protons to electrons increases and thus the electrons are held closest and with more strength

65
Q

why do anions expand

A

the nucleus is not attracting more electrons than there are protons
enchanted electron/electron repulsions

66
Q

whats the deal w isoelectric ions

A

consider the number of protons to determine size (i.e F has one more proton than O which further attracts the electron cloud so its smaller)

67
Q

what is the trend with reactivity

A

metals are more reactive as you move down a column

non metals are more reactive as you move up a column

68
Q

why are metals more reactive as you move down a column

A

b/c metals react by losing electrons, a loosely held electron will result in a more reactive metal. With an increase number of energy levels (n) comes increased distance from the nuclear attraction and thus a more loosely held electron available for reacting

69
Q

why are nonmetals more reactive as you move up a column

A

b/c nonmetals tend to gain electrons, a strong nuclear attraction will result in a more reactive non-metal. This means an atom with the highest Zeff and the least number of energy levels should be the most reactive nonmetal b/c its nucleus exerts the strongest pull