Chapter 5 Arrangement of Electrons in Atoms. LightLight Dual Nature of Light: Light can act like...
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Chapter 5 Arrangement of Electrons in Atoms. LightLight Dual Nature of Light: Light can act like waves, and as straight line particles. Light is one type
LightLight Dual Nature of Light: Light can act like waves, and
as straight line particles. Light is one type of _____________
____________which is a form of Energy that has wavelike behavior
Other types of em radiation are: x-rays, uv, infrared, microwaves
& radio, and together they all form the
_____________________________ (look at p.92 Figure 4-1 on next
slide)
Slide 3
Slide 4
The Wave The speed of all em waves through a vacuum (space) and
through air is: _______________________________ The length of each
individual wave is known as its __________________ ( ) which is the
length between corresponding points on adjacent waves, usually
measured in ____________ (1nm = 10 -9 m) The ______________ (f or )
is how many waves pass a particular point in a second and is
measured in waves/second = _________ (Hz)
Slide 5
The relationship between them is as follows: c = f x E.g. What
is the wavelength & color of light that has a frequency of 6 x
10 14 Hz (1/s)? f = c = = c = f x
Slide 6
If em radiation is directed towards a piece of metal, it may
have enough energy to knock out electrons. This is known as the
________________________. A German physicist: Max Planck, explained
the reason why, but first lets look at what he discovered.
Slide 7
When an object gets hot, it emits energy in small specific
amounts called quanta. A quantum is the minimum amount of energy
that can be lost or gained by an atom. The frequency determines the
Energy by: ________ Where Plancks constant = h = ______________
E.g.What is the Energy of Green light with a frequency of 6 x 10 14
Hz ? f=f= E = h.f
Slide 8
It was Einstein that proposed that light acted like a stream of
particles called photons. A ___________ is a particle of em
radiation that has zero mass and carrying a _______ of energy There
must be a minimum amount of energy to eject electrons from a metal
__________, Planck realized that the em radiation providing the
energy, must be of a certain frequency. Different metals need
different minimum amounts of energy, and therefore frequencies
Slide 9
The Hydrogen Atom Consider the H atom with its one electron
spinning around its one proton. When the electron is closest to the
proton/nucleus which is at its lowest energy state, the atom is in
its ground state. When energy, like heat, is supplied to the atom,
the electron jumps to a higher orbit which is at a higher energy
state. The atom is now in an excited state.
Slide 10
When the electron _______________________
_______________________ or a lower energy state, it emits a photon
of radiation with a specific amount of energy, and not continuous
amounts of energy. Therefore, specific ______________ of light are
emitted when excited Hydrogen cools down.
Slide 11
Bohr Model Niels Bohr (Danish) proposed a model that stated:
the e - of a H atom can circle the nucleus in allowed paths called
__________ Between the orbit and the nucleus, is a large empty
space where the e - ___________ exist
Slide 12
When the ____ atom gets excited, the e - jumps to another
specific orbit and not somewhere in between like going up a ladder
When the e - falls back, it ______ ______ in the form of a photon
(a bundle of light energy) Convert circular orbits to lines
Slide 13
The amount of Energy is _______ to the difference in the two
_________ (orbit) levels So there are specific frequencies (colors
of light) given off when the H e - ______ from the higher orbits
giving its visible line spectrum
Slide 14
Quantum Model of Atom Question is: Why cant e - s be in an
orbit between the ________ Energy levels? French scientist Louis
DeBroglie pointed out that the electron orbits acted like the
behavior of waves. i.e. you can only have a certain amount of waves
in a given _________________ not of a wave If you can only have
specific # of waves, then based on the formula _______ you can only
have specific fs, which in turn translates into specific Energy
levels.
Slide 15
Heisenberg Uncertainty Principle States that: it is impossible
to determine _____________ the position and velocity of an electron
or any other particle This is because whatever you use to observe
subatomic particles, will affect the particles themselves. i.e you
cant observe/measure without disturbing it.
Slide 16
Quantum Numbers ____________________(n) indicates the main
energy level (or shell) occupied by the electron. Principle
_____________________ is also referred to as the Principle Energy
Level (n). n = 1,2,3,4 where n = 1 is the closest to the nucleus.
(Diagram: H atom Circular orbits to linear 1,2,3,)
Slide 17
The electron now has an __________ number of Energy levels
(shells) to jump to depending on the Energy input.
Slide 18
Each Energy level (n) divides up further into
sublevels/subshells. How many divisions depends on the original
Energy level. The1 st E level has1 sublevel (s only) 2 nd 2
sublevels (s and p) 3 rd 3 sublevels (s, p, and d) 4 th 4
sublevels(s, p, d and f) : : i.e n th n sublevels.
Slide 19
s-Orbital Each sublevel is assigned an ___________ __________
_________ ( l ) and has a particular shape. The first sublevel in
each E level has a spherical shape. (assigned the letter s ). There
is only 1 possible orientation. (aka orbital) The shape is
determined by the electrons path over time.
Slide 20
p- Orbital The ________ ________in each E level has a figure
eight shape. (assigned the letter p ). There are 3 possible
orientations (orbitals)
Slide 21
d- orbital The _______ _______in each E level is designated an
has a four leaf clover shape. (assigned the letter d ). There are 5
possible orientations (orbitals)
Slide 22
Slide 23
f, g and h are indescribable! The _______ ________in each E
level has an indescribable shape. (assigned the letter ___ ). There
are 7 possible orientations (orbitals) The ________ _________in
each E level has an indescribable shape. (assigned the letter ___
). There are 9 possible orientations (orbitals). The _______
________in each E level has an indescribable shape. (assigned the
letter ____ ). There are 11 possible orientations (orbitals).
Summary on board
Slide 24
To sum up:. Principle E level# sublevelssublevels (n)(n). 111s
222s 2p 333s 3p 3d 444s 4p 4d 4f 555s 5p 5d 5f 5g 666s 6p 6d 6f 6g
6h We expect the order of the orbitals to increase as follows: 1s
2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 5g 6s 6p
Slide 25
But in reality, from Energy level 3, there are some overlaps.
There is an easy way to determine the actual order. ( demonstrate
diagonal method) So, the actual order is as follows: 1s 2s 2p 3s 3p
4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p 8s
Slide 26
Now each _______ (orientation) can hold 2 ________. The s
sublevel which has1 orbital can hold 2 e - s p36p36 d510 f714 g918
h1122.
Slide 27
So now, the BIG picture is as follows:.. Principle## of
eachTotalTotal E levelsublevelstype of# of# of orbitalorbitalse - s
(n)(n)s p d f g h(n 2 )(2n 2 ) 1111 221 34 331 3 59 441 3 5 716 551
3 5 7 925 661 3 5 7 9 1136
Slide 28
Electron Configuration Each orbital (orientation) can hold
_____and can be represented by a box, circle or underline.
(diagram)(complete orbital chart) For each electron, they orbit
with a spin around in 2 different ways ________________________.
One type of spin produces a magnetic field with a North up
(_________), and the other produces a North down (__________)
(diagram) The electrons are represented by _______ pointing up or
down, depending on their spin. (diagram)
Slide 29
According to the: Pauli Exclusion principle, in order for 2
electrons to occupy the same orbital, they must have opposite
spins. e.g. Hydrogen has 1 e- that occupies the lowest Energy level
1s. 1s Helium has 2 e-s that also occupies the lowest Energy level
1s. 1s Opposing arrows that represent opposite spins.
Slide 30
Rules of Procedure for Electron Configuration: 1. ___________:
an electron occupies the lowest energy orbital that can receive it.
(i.e. start from the bottom) 2. ____________________: no 2
electrons in the same atom can have the same set of 4 quantum
numbers. (i.e. no more than 2 electrons per orbital) 3.
________________: orbitals of equal energy are each occupied by one
electron before any orbital is occupied by a 2 nd electron, and all
electrons in singly occupied orbitals must have the same spin.
(i.e. dont double up until each orbital has an up arrow)
Slide 31
Now do Oxygen & explain:
Slide 32
_______________________: the way electrons are arranged amongst
the orbitals. A special notation is used which consists of: the
principle E level, the sublevel & the # of electrons in that
sublevel. e.g. the 1 electron in Hydrogen occupies the 1 st
orbital, in the 1 st sublevel, in the 1 st E level. (diagram) e.g.
the 2 electrons in Helium also occupy the 1 st orbital, in the 1 st
sublevel, in the 1 st E level. (diagram) e.g. for Lithium, which
has 3 electrons, its as follows: (diagram)