The electrons and the quantum mechanical model Flashcards

1
Q

electromagnetic radiation

A

consists of energy particles that move as waves of energy

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2
Q

planck’s constant

A

6.626 x 10^-34 m2 kg/s =Js

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3
Q

equations for electromagnetic radiation

A

c= vλ

E= hv = hc/λ

h= planck’s constant

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4
Q

electromagnetic spectrum

A

radiowaves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays

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5
Q

atomic spectrum

A

when light from a heated element passes through a prism, it separates into distinct lines of color separated by dark areas. each element has its unique atomic spectrum of distinct lines

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6
Q

what are the lines in an atomic spectrum are associated with

A

with the changes in the energies of the electrons

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7
Q

quantum

A

very specific levels where the energy of the electron is limited to

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8
Q

principal quantum number

A

energy levels

n=1, n=2, n=3

energy increases as the value of n increases and electrons are further away from the nucleus

distances decrease quadratically

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9
Q

when do electrons move to a higher energy level

A

when they absorb energy

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10
Q

how can you promote an electron to a higher energy level?

A

provide an amount of energy equal to the level difference

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11
Q

what happens when an electron falls back to a lower energy level?

A

light is emitted

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12
Q

what is the energy emitted or absorbed equal to

A

the difference between 2 energy levels

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13
Q

why cannot Bohr’s model be correct?

A
  1. electrons moving at a constant speed around the nucleus would emit energy and this does not happen
  2. electrons would progressively slow down and fall on the nucleus and this does not happen
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14
Q

particle-wave duality of subatomic particles

A

electrons can behave like a particle or a wave

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15
Q

the electron has a wavelength equal to:

A

λ= h/mv

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16
Q

uncertainty principle

A

we cannot know exactly the position and speed of an electron

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17
Q

why do we want to know where the electron is around an atom?

A

if the electron is closer to the nucleus it is less prone to share with other elements and thus its position can influence the atom’s reactivity: electrons with the same levels of energy will form more stable bonds

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18
Q

what does the wave function depend on?

A

on the number of electrons in the atom

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19
Q

what is the value of the square of the wave function ψ^2?

A

the probability of finding an electron in a specific region in space

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20
Q

what does the wave function depend on?

A

values of the wave function depend on 3 integer numbers: n,l,m

21
Q

orbitals

A

volumes in space where we have a defined probability of finding an electron

22
Q

energy of a hydrogen atom

A

E= -1/n^2 x 2.18 x 10^-18 J

23
Q

the 4 quantum numbers

A
  1. principal quantum number
  2. angular momentum quantum number
  3. magnetic quantum number
  4. electron spin number
24
Q

angular momentum quantum number

A

l
describes the shape of the regions where there is non-zero probability of finding an electron

eg. if n=3, l= 0,1,2

25
magnetic quantum number
m specifies the orientation in space of the orbital if n=3, m=-2,-1,0,1,2
26
electron spin number
s +- 1/2 if an electron is placed in a mf its energy will be based on the direction it spins in
27
how many orbitals in a level
n^2
28
how many orbitals in a sublevel
2l + 1
29
l=0, l=1, l=2, l=3
l=0 s l=1 p l=2 d l=3 f
30
what do wave functions contain
at least one node: the point where the wave function has a value of zero, and thus regions with a probability of finding the electron is zero
31
what happens as we go further up in energy
we will have more nodes nodes are proportional to n: number of nodes n-1
32
level n=2
l can assume the value of 1, referred to as p orbital. m ca be equal to -1, 0, 1 so there are 3 p orbitals. A p orbital has 2 regions of high probability which gives a dumbshell shape 
33
wave function
describes the probability of finding a particle
34
what does it mean if an orbital has a node?
it can have positive and negative phases: which important for chemical bonding
35
Pauli exclusion principle
1. each orbital can hold a maximum of 2 electrons 2. electrons in the same orbital repel each other (coulomb's law) 3. electrons in the same orbital must have their magnetic spins cancel
36
madelung- kleckovskij rule
atomic orbitals are filled in order of increasing n+l
37
why is E(s) < E(p) < E(d) < E(f)
1. shielding: when an electron is further away from the nucleus, it feels a nuclear charge that is partially shielded by the inner electrons. it experiences a charge Z(eff)
38
chromium configuration
[Ar] 4s1 3d5
39
copper configuration
[Ar] 4s1 3d10
40
lewis symbols
represent the valence electrons as dots placed on sides of the symbol of an element
41
describe how atomic size changes along a period and going down a group 
atomic size increases going down a group but decreases going from left to right across a period 
42
what determines the atomic size
by the atom's atomic radius, the distance between the nucleus and the outermost electron-accessible orbital.
43
ionisation energy
the energy needed to remove one mole of the outermost electrons in the gaseous phase
44
describe how ionisation energy changes 
as the distance from the nucleus to the valence electrons increases, the ionisation energy decreases. ionisation energy decreases down a group as the distance between the nucleus and valence electrons increases.  ionisation energy increases as we move along a period as the number of protons strengths the attraction of the nucleus for the valence electrons 
45
how can divalent cations be obtained?
from 2 subsequent ionisations
45
how does the first ionization energy compare to the second ionization energy?
the first one if smaller than the second one
46
electron affinity
the energy released by an element when it gains an electron
47
describe whether electron affinity is endothermic or exothermic
1st EA: endothermic 2nd EA: exothermic
48
describe how metallic character changes
as we go down a group metallic character increases because the valence electrons are easier to remove when they are further from the nucleus  as we go along a period metallic characteristics decrease as the number of protons increases which strengthens the attraction of the nucleus for the valence electrons and makes it more difficult to remove a valence electron.