Chapter 5 Flashcards
Rutherford’s Model
Positive charge + all of mass is in a concentrated nucleus surrounded by electrons
EM radiation
Energy that exhibits wavelike behavior as it travels through space
Wavelength
λ, is the shortest distance between equivalent points on a continuous wave
1 nm
10-9 m
Frequency
v, The number of waves that pass a given point per second
Hertz
One wave per second
SI Unit of frequency
Hertz
____ s-1
Used to measure frequency, is equivalent to Hertz. Is used to express “waves per second”
Amplitude
The length from the origin of a wave to its crest/trough.
c
Speed of light
c=?
c=λv c=wavelength*frequency c=3.00*108 m/s
Frequency and wavelength are _____ related
Inversely
White light
Contains a continuous range of wavelengths and frequencies. For example, sunlight passing through a prism is separated into a continuous spectrum of colors.
Visible spectrum
The colors we an see w/ a human eye
Why is a spectrum continuous?
There is no portion that does not correspond to a unique wavelength and frequency of light.
How is a rainbow formed?
Drops of water in the air disperse the white light from the sun to it’s component colors to form a rainbow.
Electromagnetic Spectrum
AKA the EM spectrum, encompasses all forms of EM radiation.
The only differences between the types of EM radiation are ______?
Frequency and wavelength. Speed (c) remains the same (3.00*108 m/s)
What wavelengths bend more as the pass through a prism?
Long wavelengths bend more.
What color of visible light has the longest wavelength?
Red
What is the order of colors in visible light from the longest wavelength to the shortest wavelength?
Red, Orange, Yellow, Green, Blue, Indigo, Violet
Energy is directly proportional to ______
Frequency (v)
Energy is inversely proportional to _______
Wavelength (λ)
What color of visible light has the most energy? Why?
Violet; it has the highest frequency.
List the EM spectrum in terms of longest wavelength to shortest wavelength
Radio, Microwaves, Infrared, Visible light, UV, X rays, Gamma
What type of EM radiation has the most energy?
Gamma rays
What type of EM radiation has the least energy?
Radio
List the EM spectrum in terms of lowest frequency to highest frequency
Radio, Microwaves, Infrared, Visible light, UV, X rays, Gamma
Max Planck
Studied light emitted from heated objects: Matter can gain or lose energy only in small, specific amounts called quanta.
Quantum
The minimum amount of energy that can be gained or lost by an atom
Glowing objects emit light, a form of energy. This emitted light energy is _______.
Quantized. (Propsosed by Planck)
Matter, regardless of its form, can gain or lose energy only in small _____ amounts.
Quantized.
Equantum=?
e=hv; where e is energy, h is Planck’s constant and v is frequency.
Planck’s constant
6.626*10-34 Joules seconds
What is the SI unit of energy?
Joules
What two equations are NOT THE SAME
c=λv (Speed of light = wavelength * frequency) e=hv (Energy = Planck’s constant * frequency)
Matter can emit or absorb light only in _______
Whole number multiples of hv; that is, 1hv, 2hv, 3hv, etc.
What is an analogy of the concept of quantized energy?
For example a child building a wall of wooden blocks. The child can only take away height from the wall in a whole number of blocks. Fractions of blocks are not possible. In the same way, matter can have only certain amounts of energy. Quantities between these values of energy do not exist.
Photoelectric effect
Electrons are emitted from a metal’s surface when light of a certain frequency shines on the surface.
Photoelectric cells
Convert light into electrical energy (for example a solar powered calculator)
The wave model predicts what about the photoelectric effect?
Given enough time, even low-energy, low-frequency light would accumulate and supply enough energy to eject photoelectrons from a metal.
Why is the wave model incorrect?
A metal will not eject photoelectrons below a specific frequency of incident light, no matter how intense or how long it shines.
Who explained the photoelectric effect?
Einstein
Einstein said that EM radiation has both _____ and ____ properties
Wave and particle.
While a beam of light has many wavelike characteristics, it also can be thought of as a tiny stream of particles, or bundles of energy, called ____
Photons.
Photon
A particle of EM radiation with no mass that carries a quantum of energy
Einstein’s equation which was similar to Planck’s idea of constant energy was:
Ephoton=hv
For the photoelectric effect to occur ___________
A photon must possess the energy required to free an electron from an atom of the metal.
(True/False) Even small numbers of photons with energy above the threshold value will cause the photoelectric effect
True
Atomic Emission Spectrum
The set of frequencies of the EM waves emitted by the atoms of the element.
(True/False) Each element’s atomic emssion spectrum is unique and can be used to determine if that element is part of an unknown compound.
True
What are ways to excite electrons to a higher energy level?
Electricity [gas tube], heat [flame tests]
Bohr’s model of the atom
The hydrogen atom only has certain allowable energy states. The single electron orbits hydrogen in circular orbits. The smaller the orbit, the lower the energy level.
Ground state
The lowest allowable energy state of an atom
Excited state
When an atom gains energy
(True/False) Because the hydrogen atom contains only a single electron, it is capable of having only one excited state.
False. It can have many excited states.
ΔE=?
Ehigher-energy orbit - Elower-energy orbit = Ephoton = hv
The visible series of spectrum lines is called the _____
Balmer Series; when electrons drop to the n=2 energy level.
Lynman series
UV light; when electrons drop to the n=1 energy level.
Paschen Series
Infrared; when electrons drop to the n=3 energy level.
(True/False) An atom’s energy levels are evenly spaced
False. The distance between energy levels gets smaller and smaller as the levels get bigger.
de Broglie equation
λ=h/mv, where λ is wavelength, h is Planck’s constant, and v is velocity
(True/False) All moving particles have wave characteristics
True
Why can’t you see the wavelengths of objects in motion?
Because the mass of these objects is so big that the wavelength is far too small to see.
Heisenberg Uncertainty Principle
It is fundamentally impossible to know both the velocity and the position of a particle at the same time.
Shrodinger wave equation
Treated the H atom’s electron as a wave. It worked for other elements too, unlike Bohr’s model.
Quantum Mechanical model of the atom (Wave mechanical model of the atom)
Electrons are treated as waves. Like Bohr’s model, an electron’s energy is restricted to certain values. However, it makes no attempt to describe the electron’s path around the nucleus.
Wave function predicts _____
The electron’s location in an atom
Atomic Orbital
A 3D location around the nucleus that describes the electron’s probable location.
The orbital is where an electron is _____% of the time
90%
Principal Quantum Numbers
(n) Indicates the relative sizes and energies of atomic orbitals.
As n increases, the electron ________
spends more time further from the nucleus, and the atom’s energy level increases
Principal energy levels
n specifies the atom’s major energy levels. An atom’s lowest principal energy level is assign a quantum number of 1.
How many energy levels have been detected for hydrogen?
n=1-7
Energy sublevels
s, p, d, f orbitals.
Principal energy level n contains ____ sublevels
n sublevels
Each energy sublevel contains how many degenerate orbitals?
s: 1
p: 3
d: 5
f: 7
Number of orbitals related to principal energy level
n2
Electron configuration
Electron’s arrangement in an atom
Aufbau principle
Each electron occupies the lowest energy orbital available
Pauli exclusion principle
Two electrons may occupy a single orbital, but only if they have opposite spins
Hund’s Rule
Single electrons with the same spin must occupy each degenerate orbital before additional electrons with opposite spins can occupy the same orbital.
What is the electron configuration for chromium?
[Ar]4s13d5
What is the electron configuration for copper?
[Ar]4s13d10
Valence electrons
Electrons in the s and p orbitals
Angular quantum number
The shape of the orbital (spdf)
Starts at 0 for s, 1 for p, etc.
Magnetic quantum number
(m), any number from +- l (the anuglar quantum number).
So for example, if l=2, m could be -2,-1,0,1,2
