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108 Cards in this Set
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Atoms and molecules are governed by same or different laws?

Atoms and molecules are not governed by the same physical laws as larger objects


Max Planck discovered?

Energy is continous, and Atoms and molecules emit energy only in certain discrete quantities or quanta.


What is a wave?

vibrating disturbance by which energy is transmitted


How do water waves travel?

Wave repeats itself at regular intervals.


Waves can be characterized by?

length, height, and number of waves per second


What is wavelength?

distance between identical points on successive waves


What is frequency?

number of waves that pass through a particular point in 1 second


What is amplitude?

vertical distance from the midline of a wave to the peak or trough


What is speed?

Depends on the type of wave and nature of the medium. Speed is a product of wavelength and frequency
u = yV 

What is wavelenght and frequency measured in?

m, cm, nm.
1 Hz = 1 cycle/second 

Visbile light is made up of?

Electromagnetic waves


What are Electromagnetic waves?

Waves with an electrical field component and a magnetic field component


The two components of electromagnetic waves differ in?

Same speed, but travel in perpendicular planes


What is electromagnetic radiation?

Emission and transmission of energy in the form of electromagnetic waves


What speed do electromagnetic waves travel at?

3.00 * 10^8 m/s


Long waves

Are emitted from large antennas (radio, cell phones). Radio waves lowest frequency


Short waves

Have higher energy radiation. Gamma rays have the shortest wavelenght and highest frequency


What is quantum?

smallest quantity of energy that can be emitted or absorbed in the form of electromagnetic radiation


What is the wavelength (in m) of an electromagnetic wave whose frequency is 3.64 * 10^7 Hz?

ANSWER


What is the frequency (in Hz) of a wave whose speed is 713 m/s and wavelength is 1.14 m?

ANSWER


What is Planck's constant?

E=hv
H= 6.63 * 10^34 

What is the photoelectric effect?

Electrons are ejected from the surface of certain metals exposed to light of at least a certain minimum frequency called the
Threshold frequency 

Number of electrons depends on?

intensity of light but energy of electrons does not


Einstein theorized light is made up of?

A stream of particles called photons.


What do you need to break electrons free from a metal?

Requires light of sufficiently high frequency


What is KE and BE?

E = hn = KE + BE
KE = kinetic energy of electron BE = binding energy of the electron in the metal The higher the frequency the greater the KE 

KE is dependent on?

Frequency of the light. Ejected


Light behaves as?

Both as a particle and wave depending on the property being measured. All matter actually exhibits this dual nature.


The energy of a photon is 5.87 * 1020 J. What is the wavelength in nm? h = 6.63 * 1034 J*s
A photon has a wavelength of 624 nm. Calculate the energy of the photon in J. 
ANSWER


What is an emission spectra?

Either continous or line spectra of radiation emitted by substances


What is a line spectra?

The light emmission only at specific wavelenghts. Produced by atoms


Continous

Emission spectra of the sun or heated solids


Why is Bohr's model no accurate?

Because it does not explain the spectral lines


What is Rydberg's constant?

Rydberg constant (RH) = 2.18 * 10^18 J
Energy of electron 

Where are free electrons?

infinitely far from the nucleus


Why is there a negative sign in equation of Rydberg's constant?

Negative sign – is to assign a lower energy of electron in an atom than the energy of the free electron (arbitrarily assigned a value of zero)


What happens as the electron gets closer to the nucleus?

Becomes more stable and E becomes more negative, which corresponds to the most stable state.


What is the ground state?

The lowest energy state of a system or most stable


What is the excited state?

Higher energy than the ground state


When is radiant energy emitted?

When electrons drop from a higher energy orbital to a lower energy orbital


The quantity of energy produced is dependent only on what?

Initial and final states
If an electron starts at ni and drops to a lower energy state of nf the change in energy is given by Equation= 

What happen in the states when energy is given off.

Ni>Nf change in energy is negative


Each line on the emission spectrum corresponds to?

To a transition in the H atom
When a large number of H atoms are examined all the lines of the spectrum are visible 

Electrons bound to a nucleus behave like?

Electrons bound to a nucleus behave like a standing wave
Waves that can be generated by plucking a string 

Some points on a standing wave are

Nodes
Do not move at all The amplitude at this point is zero Nodes are located at the end of the string and maybe in the middle 

De Broglie says that if an electron does not behave like a wave then?

De Broglie said that if an electron does behave like as wave then the wave must perfectly fit the circumference of the orbit
The circumference of the orbit is related to the wavelength by the equation = 

When can a particle be a wave and a wave be a particle?

A particle in motion can be treated as a wave
A wave can also exhibit properties of a particle 

Protons can be accelerated to speeds near the speed of light in particle accelerators. Estimate the wavelength (in nm) of such a proton moving at 2.90 * 108 m/s. (mp = 1.673 * 1027 kg)
A baseball has a mass of about 255 g. Calculate the wavelength of the baseball if it is thrown 100. mph. 
Answer=


What is Heisenberg uncertainity principle?

It is impossible to know simultaneously both the momentum p and the position of a particle


Applying the Heisenberg uncertainty principle to the H atom?

We see that the electron can not orbit the nucleus in a circular orbital.
If this were the case then we could know both the position and momentum of the electron at the same time. 

Erwin schrodinger formulated what?

Formulated an equation to describe the behavior and energies of submicroscopic objects
This equation is very complicated and requires Calculus to solve 

The equation incorporated?

The Schrödinger equation incorporates particle behavior of electrons in the form of mass and wave behavior in the form of wave function (y)


Why is the wave funciton significant?

Is that the square of the wave function (y2) is proportional to the probability of where the electron is located


Where is an electron most likely to be?

The most likely place an electron will be is where y2 is greatest


What tells Schrodinger equation tell us?

The Schrödinger equation gives possible energy states and identifies the wave function of the electrons.
These are characterized by quantum numbers. Quantum mechanics gives probability of an electron in a particular region of the atom (electron density) 

In quantum mechanics the orbits are called?

Atomic orbitals


What is an atomic orbital?

The wave function of an electron in an atom.
This is to differentiate from the orbits in Bohr’s model. Each atomic orbital has a characteristic energy and therefore a characteristic distribution of electron density. 

An assumptions must be made

The difference between hydrogen and atoms with more than one electron is not that large.


What are quantum numbers?

Describe the distribution of electrons in hydrogen and other atoms.


What are three quantum numbers that describe the distributioni of electrons?

Principal quantum number
Angular momentum quantum number Magnetic quantum number 

What is the fourth quantum number that describes the behavior of a specific electron?

Spin quantum number


Principal quantum numbers

Represented by n
Can have values of integers Relates the average distance from the electron to the nucleus in a particular orbital. 

Larger the n what happens?

The greater distance of an electron in the orbital from the nucleus and therefor the larger the orbital.


Angular Momentum Quantum Number

Represent by l
Tells the shape of the orbital Dependent on n For any n, l = any integer from 0 to (n1) For n = 1, l = 0 For n = 3, l = 0, 1, or 2 l is normally designated by the letter that symbolizes the different atomic orbitals 

Magnetic quantum number

Represented by ml
Depends on l For any value l, there are (2l +1) values for ml If l = o then ml = 0 If l = 1 then there are three possible values of ml, (1, 0, 1) The value of ml indicates the number of orbitals in the subshell with value l 

Spin quantum numbers

Represented by ms
It was noticed that the application of a magnetic field could split the lines in an emission spectra The only way this could be explain is if electron behave as tiny magnets If the electrons are thought of as spinning on their own then the magnetic field can be explained The spinning charge generates a magnetic field 

Spin quantum numbers are always?

–½ or +½


Atomic orbital related to angular momentum




What is a shell?

A collection of orbitals with the same value of n


What are subshells?

Orbitals with the same n and l value are called subshells
For example n = 2 Two subshells: l = 0 and l = 1 Called the 2s and 2p subshells 

What is the shape of the orbitals?

Shapes are not well defined
Wave function defining orbital extends from the nucleus to infinity It is convenient to think of the orbitals as having a shape It is especially helpful when talking about chemical bonds 

What shape and size are s orbitals?

All s orbitals are spherical
The s orbitals do change in size however The increase in size is the reason for the increase in the principal quantum number 

Electron density

Falls off rapidly as the electron get farther from the nucleus.


p orbitals start with the principal quantum number? What happen when n=2, and l=1?

2
three possible orbital so there are 3 2p orbitals 

What are the shape, and size of orbitals?

They are oriented along the axes of a 3d plot
The three orbitals differ only in the orientation They are identical in shape, size and energy p orbital are thought of as two lobes on either side of the nucleus 

d orbitals

n must equal at least 3 and l must equal 2 for the d orbitals to exist


How many d orbitals are there?

There are 5 d orbitals
The orbitals differ in orientation as well as one having a different shape. All 3d orbitals have the same energy d orbitals which have a larger n value have similarly shaped orbitals that are larger 

Why are f orbitals important?

are important for accounting for the behavior element with atomic number > 57
In this class we are not concerned with orbitals having l > 3 

Give the quantum numbers associated with the following orbitals:
2p 3s 5d 



Energy of orbitals increase as?

n increases
1s<2s=2p<3s=3p=3d<4s=4p=4d=4f<… 

Does electron density change for 2s and 2p orbitals?

Although the electron density is different for 2s and 2p orbitals the energy remains the same


Which is orbital is the most stable?

1s


The total energy depends on what?

The total energy depends on the sum of orbital energies as well as the repulsive forces
It turns ends up that the total energy is lower when the 4s orbital fills before the 3d 

Order of atomic orbitals filling

1s
2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 7s 7p 

2s quantum numbers




Ms

has no affect on energy, size, shape, or orientation of the orbital but determines how electrons are arranged in an orbital


What is electron configuration?

How the electrons of an atom are distributed among the orbitals
This is how the electrons are distributed in a ground state atom 

The number of electrons in an atom is equal to?

Atomic number


Ground State H




Pauli exclusion principle?

No two electrons in the same atom can have the same four quantum numbers.
If they have the same n, l, and ml, then they must have different ms. These two electrons would be in the same orbital but have opposite spins. Thus each orbital can contain only two electrons 

Paramagnetism

Contain net unpaired spins and are attracted by a magnet


Diamagnetism

Do not contain unpaired spins and are slightly repelled by a magnet. A He atom with opposite spins in the orbital


What happens if the spins in an orbital do match up?

The magnetic fields reinforce each other. This would make an atom paramagnetic.


Odd and even numbered atoms have?

Odd numbered atoms always have one or more unpaired electrons
Even numbered atoms may or may not have unpaired electrons 

Which orbital is filled first?

The 1s orbital is filled before electrons are start to fill the 2s or 2p orbital


2s and 2p orbitals

Both the 2s and 2p orbitals have electrons that spend more time away from the nucleus than electrons in the 1s orbital
The electrons of the 2s and 2p orbitals are shielded from the attractive forces of the nucleus by the 1s electrons This reduces the electrostatic interactions between the nucleus and the 2s and 2p electrons 

Shielding

Experimentally the 2s orbital gives us a lower energy than the 2p
Although the 2s electron spend more time on average farther from the nucleus than a 2p electron; the denisty near the nucleus is greater for a 2s electron So the 2s orbital is more penetrating The 2s orbital is less shielded For the same values of n, the penetrating power decreases as l increases 

How is the stability of the electron is determined?

The stability of the electron is determined by the strength of attraction to the nucleus


Shielding effect

2s orbitals are less shielded than 2p orbitals so it follows that 2s orbitals have lower energy. Less energy is required to remove a 2p electron than a 2s electron


Hund's Rule

The most stable arrangement of electrons in subshells is the one with the greatest number of parallel spins


Rules for assigning electrons to orbitals

Each shell (or principal quantum number) n contains n subshells
Each subshell consists of quantum number l contain (2l + 1) orbitals No more than 2 electrons can be placed in an orbital The maximum number of electrons in principal level n is equal to 2n2 

How many electrons can be present in the prinicpal level n=4?
What are the principal quantum numbers for the last electron in boron (B)? 



Aufbau principle

As protons are added one by one to the nucleus to build up elements, electrons are similarly added to the atomic orbitals


Noble gas core

a method of showing electron configurations where the noble gas most nearly preceding the element being considered is used.The noble gas is followed by the electron configuration of the most highly filled subshells


Transition metals have either

Have either incompletely filled d orbitals or give rise to cations that have incompletely filled d subshells


Two irregularities in the fourth preiod

Chromium – [Ar]4s13d5
Copper – [Ar]4s13d10 The reason for this is that there is actually more stability in a halffilled or filled d orbital 

Lanthanides and Actinide

Lanthanides – have incompletely filled 4f orbitals or readily give rise to cations with incompletely filled 4f subshells
Actinide series – last row of elements, most are not found in nature but have been synthesized 

Write the groundstate electron configuration for Sr.
Write the groundstate electron configuration for Ga. 

