Download chapter 7: atomic structure and periodicity

CHAPTER 7: ATOMIC STRUCTURE AND PERIODICITY
Sections 7.1 -7.3
Make sure you read these sections (pp. 292-300) and do the following BW: pp 340-41 #17,37,38,39,40,42, and 43
Electromagnetic radiation:
Examples of em radiation?
3 equations to know
1. Equation relating frequency and wavelength:
c=
λ=
ν=
h=
ν=
2. Equation relating energy and frequency:
E=
Put equations 1 and 2 together to get :
3. Equation relating wavelength and momentum of a particle, de Broglie’s equation
m=
What is a photon?
What is the dual nature of light?
Does all matter exhibit both particulate and wave properties?
What is the difference between a continuous and line spectrum?
EXAMPLE PROBLEMS:
Calculate the de Broglie wavelength for each of the following:
a) a proton with a velocity of 90.% of the speed of light.
b) a 150 g ball with a velocity of 10. m/s.
v=
17.4 The Bohr Model
According to Bohr
1) Electrons can occupy only certain _________________ around the nucleus.
2) Each orbit has an energy associated with it.
3) Energy is absorbed by an electron when it moves from a _____________ to _____________ orbit.
Energy is released (in the form of photons) when a e- moves from a _______________ to
______________________ orbit.
4) The energy of the photons emitted or absorbed is equal to the difference between the 2 orbit energies.
This explains why only certain lines of specific wavelengths appear on a line (or emission) spectrum.
To calculate energy of an “orbit” or energy level , we use the following equation:
E=
n = an integer  refers to ______________ , the larger the value of n, the _______________ the ___________.
Z=
Excited state –
Ground state –
Example Problem
a) Calculate the energy required to excite the hydrogen electron from level n = 1 to level n = 2
b) Calculate the wavelength of light that must be absorbed by a hydrogen atom in its ground state to reach this
excited state.
7.5 THE QUANTUM MECHANICAL MODEL OF THE ATOM
Problems with Bohr’s model :
A New Model – Quantum (Wave) Mechanical Model.
A mathematical model developed by __________________________, ____________________________, and
___________________ treats the electron as if it were a _____________________.
______________________ originated the idea that small particles, such as the electrons show wave properties.
Equation:
______________________ developed a wave equation in terms of wave function. His equation predicts the presence of certain
regions in the atom where electrons are likely to be found. These regions are known as
____________________________ and are 3 dimensional. The first 3 of the 4 quantum numbers were developed from this
equation.
____________________________ developed the ________________________ principle which states that it is not possible to
simultaneously determine the position and momentum of a particle, such as an electron.
7.6 QUANTUM NUMBERS/7.8 ELECTRON SPIN AND PAULI EXCLUSION PRINCIPLE
Quantum numbers describe the various properties of ______________________________.
1. Principal Quantum Number – symbol
– has integral values 1,2,3,….. The principal quantum number is
related to the _________________ and ____________________ of the orbital. As n increases, the orbital becomes
_________________ and has ________________ energy and is located _____________________ from the nucleus.
The sets of orbitals with the same n-value are often referred to as electron shells or energy levels.
2. Angular Momentum (Orbital) Quantum Number – symbol
This quantum number indicates the shape of the orbital.
- has integral values from 0 to n-1 for each value of n.
3. Magnetic Quantum Number – symbol
- has integral values between _______ and _________,
including zero. The value of ___________________ is related to the orientation of the orbital in space
relative to the other orbitals in the atom.
4. Spin Quantum Number – symbol
- describes the apparent spin of the electron.
______________ or ___________ (corresponding to the clockwise or counterclockwise spins.)
Only 2 possible values,
Pauli Exclusion Principle – states within an atom, no 2 electrons can have the same set of ___________ _______________.
Examples:
1) Write an acceptable set of quantum numbers for the one electron of hydrogen in its ground state.
2) Write an acceptable set of quantum numbers for the valence electron of highest energy in a sodium atom.
3) Write an acceptable set of quantum numbers for the valence electron of highest energy in a boron atom.
7.7 ORBITAL SHAPES AND ENERGIES
Refer to pages 311-312 in textbook to review shapes of the s, p, d, and f orbitals.
What are degenerate orbitals?
Hund’s Rule – orbitals of ___________ energy (degenerate orbitals) are each occupied by a ____________
Electron (with parallel spins) before any one orbital is occupies by a ______________ electron.
Paramagnetic – contains one or more _____________ electrons – attraction towards a magnetic field.
Diamagnetic – all electrons are _____________________ - weak repulsion by a magnetic field.
Types of electron configurations
1. Orbital Notation
Write the orbital notation for the carbon atom.
2. Complete Electron Configuration
Write the complete e- configuration for the calcium atom.
3. Noble Gas (shorthand) Electron Configuration
Write the noble gas configuration for the bromine atom
Write the noble gas configuration for the Hafnium (Hf) atom.
HOMEWORK
(All to be done on notebook paper)
HOMEWORK ASSIGNMENT 9/29
1. Neutron diffraction is used in determining the structures of molecules.
a) Calculate the de Broglie wavelength of a neutron (1.675 x 10-27 kg) moving at 1.00% of the speed
of light.
b) Calculate the velocity of a neutron with a wavelength of 75 pm.
2. Calculate the wavelength of light emitted when the following transition occurs in the hydrogen atom:
a) n = 4  n = 2 .
b) n = 5  n = 4
HOMEWORK ASSIGNMENT 10/3
1. Which of the following orbital assignments are incorrect : 1s, 1p, 7d, 9s, 3f, 4f, 2d ?
2. Which of the following sets of quantum numbers are not allowed in the hydrogen atom? For the sets of
quantum numbers that are incorrect, state what is wrong in each set.
(a) n = 3, l =2, ml = 2
(b) n = 0, l =0, ml = 0
(c) n = 4, l =3, ml = 4
(d) n = 2, l =-1, ml = 1
3. Give the maximum number of electrons in an atom that can have these quantum numbers:
(a) n = 0, l =0, ml = 0
(d) n = 2, l =2
(b) n = 2, l =1, ml = -1, ms = -1/2
(e) n=1, l =0, ml = 0
(c) n = 3
HOMEWORK ASSIGNMENT 10/5
1. Give a possible set of 4 quantum numbers for all the valence electrons in an atom of arsenic in its
ground state.
2. Which of the following sets of quantum numbers are allowed? For sets that are incorrect, state what
is wrong.
(a) n = 7, l =7, ml = 0
(c) n = 7, l =0, ml = 1
(b) n = 7, l =5, ml = -3
(d) n = 3, l =-1, ml = 0
3. Which of the following electron configurations corresponds to an excited state? Identify the atoms and
write the ground state electron configuration where appropriate.
(a) 1s22s23p1
(c) 1s22s22p43s1
(b) 1s22s22p6
4. Write orbital notations for the following atoms:
(a) Nitrogen
(d) [Ar] 4s23d54p1
(b) Magnesium
5. Write complete electron configurations for the following atoms:
(a) Chlorine
(b) Strontium
6. Write the shorthand electron configurations for the following atoms:
(a) Pb
(b) As
(c) W
7. Is zinc paramagnetic or diamagnetic? Justify your answer.
(d) Cf