Chemistry Chapter 5

frequency (nu)

# of wave cycles to pass a point per unit of time; measured in s^-1 or 1/s

Bohr Model/Planetary model of the atom

-electron revolves around the nucleus in a circular orbit -orbits have specific distances from the nucleus (energy levels) -energy level repres. by n -ground state is the most stable state

Magnetic quantum number (m with a small l)

3D orientation in space of the energy sublevel

Visible spectrum

All the colors combined give you white light. What is this spectrum called?

Hund's rule

Degenerate orbitals must be filled before you move to another

Electromagnetic radiation

Energy waves that travel at 3.0 x 10^8 m/s in a vacuum

Clinton Davisson (Nobel) and Lester Germer's experiments

Experiments by who confirmed that matter moves like a wave?

Niels Bohr

Explained the emission spectrum of hydrogen

Albert Einstein (Nobel Prize in 1921)

Explained the photoelectric effect with quantum theory

low/short

High frequency corresponds to _______ wavelength

Bohr's model describes electrons in fixed orbits rather than in a cloud and with fixed energy levels.

How did Bohr's model differ from that of Rutherford?

They emit energy and move down an energy level.

How do electrons become stable again?

E=hv

How much is one quantum of energy?

It must emit energy (in the form of light)

How will an electron move down an energy level?

It must gain energy/become excited/reach and excited state

How will an electron move up an energy level?

Wave particle duality (De Broglie, 1924)

If light can behave like a particle then particles can behave like waves.

high/long

Low frequency corresponds to _______ wavelength

Discrete energy levels and energy is absorbed/emitted

Name 2 key ideas from Bohr's model.

Hertz (Hz)

SI Unit of cycles per second (s^-1 or 1/s)

Einstein's experiment on the photoelectric effect

Shone light on alkali metals and the electrons were knocked out of the metal

Excited states

States higher than the ground state

Newton

Studied the continuous spectrum of the sun

Electron configurations

Tells you where electrons of an atom are

Max Planck

The scientist that tried to explain color change with temperature increase

False: There are no quarter or half energy levels. Jumps occur from energy level to energy level. There is no in between.

True or False: Electrons can be in a half energy level.

True: lower energy does correspond to greater stability

True or False: Lower energy = greater stability

True (they will always have a different ms)

True or False: No 2 electrons have the same address in a particular element

False: Two electrons in an orbital can go in opposite directions

True or False: Two electrons in an orbital can go in the same direction

False: Black lines correspond to wavelengths that the element absorbed. Colored/bright lines correspond to wavelengths that the element emitted.

True or false: Black lines correspond to wavelengths that the element emitted.

False; an element's atomic emission spectrum is characteristic to that element

True or false: Some elements have the same atomic emission spectrum.

True (wavelength times frequency equals the speed of light always)

True or false: The speed of all electromagnetic radiation is the same/constant

False: Light moves like a wave but transfers energy like a stream of particles in photons/quanta

True or false: light moves like a particle but transfers energy like a wave

True

True or false: mass needs to be small for wavelength to be large enough to observe

They bombarded metals with beams of electrons. The electrons reflected and produced curious patterns. Th electrons reflected like waves.

What did Davisson and Germer do in their experiments?

Photons

What did Einstein call light quanta?

The Quantum Mechanical Model

What did Schrodinger's equation lead to?

It couldn't explain why extra lines appear when a magnetic field is applied, and it couldn't account for atoms of more than one electron.

What did the Bohr model fail to explain?

Where an electron is likely to be found.

What do orbitals describe?

3.0 x 10^8 m/s (wavelength x frequency)

What does the speed of light equal?

Why heated objects only emit certain colors; photoelectric effect

What does the wave property of light not explain?

The frequency/electricity of the light is important; how much light and how long it is shone on the metal surface does not effect the phenomenon

What factors are important in the photoelectric effect?

Water droplets forming a rainbow because the droplets refract the light.

What is a real life example of a prism that produces a spectrum?

4 lines (purple, blue, green, red)

What is the emission spectrum of hydrogen like?

energy=planck's constant x nu

What is the equation for energy?

400 to 700 nm

What is the wavelength range of visible light?

Wavelengths of spectral lines

What makes up an element's atomic emission spectrum?

They couldn't describe the microscopic properties of atoms (stability, electron configurations, etc.)

What was the failure of 19th century physicists?

Only hydrogen (1 electron); no explanation of bonding in molecules

What was the failure of the Bohr model?

They were unable to explain the behavior of electrons in an atom

What were classical physicists unable to explain?

Unstable

When electrons in an atom absorb energy and become excited they move to a higher energy level and become...

Chromium (24) and Copper (29)

Which elements are exceptions to the Aufbau principle?

High frequency/energy light such as blue light

Which type of light can cause the photoelectric effect?

Max Planck (different colors of heated metals)

Who analyzed data on radiation emitted by solids at various temperatures?

Louis de Broglie (1924)

Who asked if particles of matter can behave as waves?

Planck

Who began the work of Quantum Theory?

Thomas Young (1801)

Who observed a pattern of dark and lights stripes when light was passed through 2 adjacent slits?

James Clerk Maxwell (1873)

Who proposed that light consists of electromagnetic waves?

Einstein

Who proposed that light was a quanta of energy that behaved like particles?

Thomas Young

Who proved that light is wave-like?

De Broglie

Who said that matter is both wave-like and particle-like?

Newton

Who showed that light is made of a rainbow of colors?

Einstein (1905)

Who studied the photoelectric effect?

Isaac Newton

Who tried to explain what was known about the behavior of light by assuming that light consists of particles?

Because it is unique for each element

Why is the atomic emission spectrum a fingerprint?

emission spectrum

a spectrum of bright lines with a black background

absorption spectrum

a spectrum of dark lines with a rainbow background

Line spectrum

a spectrum with parts that are black (emission/absorption)

X-ray crystallography

a tool used for identifying the atomic and molecular structure of a crystal, in which the crystalline atoms cause a beam of incident X-rays to diffract into many specific directions

White light

consists of light with a continuous range of wavelengths and frequencies; combination of all light

Classical Mechanics

described motion of large bodies

Principal Quantum number (n)

describes the energy level

Principal Quantum Number n

describes the energy level on which the orbital resides; size and energy of the orbitals

wavelength (lambda)

distance between crests (top of one crest to the top of another); peak to peak distance measured in meters

Lyman series (ultraviolet)

due to transition form higher energy levels to n=1 in the emission spectrum of hydrogen

Balmer series (visible)

due to transition from higher energy levels to n=2

Paschen series (infrared)

due to transition from higher energy levels to n=3 (or higher)

p orbitals

dumbbell shape; l=1

Photoelectric effect

electrons are ejected when light shines on a metal

Hund's rule

electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible

energy level

fixed energies and electron can have

wavelength of a particle = h/m x v (De Broglie)

h/m x v

Planck's constant for E=h x nu

h=6.626 x 10^-34 J s

Interaxial orbitals

lobes that are between axes

Erwin Schrodinger (1926)

made and solved an equation describing the behavior of the electron in a hydrogen atom

Atomic orbitals

mathematical expression from the Schrodinger equation describing the probability of finding an electron at various locations around the nucleus

Bohr's atomic model

model in which electrons orbit around the nucleus in fixed energy levels

The Quantum Mechanical Model

modern mathematical description of electron behavior (does not specify path electrons must take)

Quantum mechanics

motion of subatomic particles as waves

William Wallaston

observed dark lines in the sun's spectrum

Degenerate orbitals

orbitals of equal energy

Aufbau Principle

orbitals of lowest energy 1st; orbitals of greater energy are higher on the diagram; sublevels of a principal energy level are of lowest energy

Axial orbitals

orbitals that lie along the axes

spin

quantum mechanical model property of electrons; clockwise or counterclockwise

Heisenberg Uncertainty Principle

says that it is impossible to know the position and velocity of a particle at the same time

s orbitals

spherical shape; l=0

M and little s

tells you the direction in which the electron is spinning (clockwise or anticlockwise)

Azimuthal/Angular momentum Quantum Number (italicized l)

tells you which sub energy level the electron is in; defines shape of the orbital (range from 0 to n-1)

quantum

the amount of energy required to move an electron from one energy level to another; minimum amount of energy that can be gained/lost by an electron

Pauli Exclusion Principle

the atomic orbital describes up to 2 electrons with opposite spins

electromagnetic radiation

the emission and transmission of energy in the form of electromagnetic waves

threshold value

the minimum amount of energy needed to knock out the electrons

Rutherford's atomic model

the model in which electrons circle around the nucleus like the planets and sun; didn't explain chemical properties of elements

electricity

the movement of electrons

Valence shell

the outermost energy level/shell

Spectroscopy (used to determine the elements in stars)

the science of using spectral lines to figure out what something is made of

Continuous spectrum (has no lines of absorption)

the sun's atomic emission spectrum

Electron configurations

the ways in which electrons are arranged in various orbitals around the nuclei of atoms

wave

vibrating disturbance that moves outward from a disturbance; destructive and constructive interference

Red light

visible light with the longest wavelength and lowest frequency

amplitude

wave's height from 0 to crest; peak height above the mid-line measured as A

Ground state

when an electron has its lowest possible energy level (principal quantum number = 1)

Node

where there is 0 probability of finding an electron (nucleus)