Chem 161 Ch 7 Terms and Connect

electromagnetic radiation

oscillating, perpendicular electric & magnetic fields moving simultaneously through space as waves. Manifested as visible light, x-rays, microwaves, radio-waves, etc.

frequency

v - the number of complete waves or cycles that pass a given point per second. 1/sec or s^-1. Hertz or Hz; inversely related to wavelength

wavelength

λ - Distance between any point on a wave and the corresponding point on the next wave (distance wave travels in 1 cycle)

speed of light

c - fundamental constant of electromagntic radoation. Travels in a vacuum. C = 2.9979 x 10^8 m/s

speed of light formula

c=λv

amplitude

the height of a wave's crest; related to the intensityh of energy (brightness)

electromagnetic spectrum

a continuum of all electromagnetic waves arranged in order of increasing wavelength

ultraviolet (UV)

Radiation region of the electromagnetic spectrum between visible and the x-ray regions

infrared (IR)

The region of the electromagnetic spectrum between the microwave and visible regions.

refraction

The bending of a wave as it passes at an angle from one medium to another

Diffraction

Occurs when an object causes a wave to change direction and bend around it

quantum number

a number that specifies certain properties of electrons

Planck's constant

Energy and frequency relationship. 6.626 x 10^-34 J x S

quantum

A packet of energy equal to hν. The smallest quantity of energy that can be emitted or absorbed.

photoelectric effect

The observation that, when monochromatic light of sufficient frequency shines on a metal, an electric current is produced.

photon

A quantum of electromagnetic radiation.

line spectrum

A series of separated lines of different colors representing photons whose wavelengths are characteristic of an element.

stationary state

In the Bohr model, one of the allowable energy levels of the atom in which it does not release or absorb energy.

ground state

The electron configuration of an atom (or ion or molecule) that is lowest in energy.

Excited state

Any electron configuration of an atom (or ion or molecule) other than the lowest energy (ground) state.

spectrometry

Any instrumental technique that uses a portion of the electromagnetic spectrum to measure the atomic and molecular energy levels of a substance.

emission spectrum

The line spectrum produced when excited atoms return to lower energy levels and emit photons characteristic of the element.

flame test

A procedure for identifying the presence of metal ions in which a granule of a compound or a drop of its solution is placed in a flame to observe a characteristic color.

absorption spectrum

The spectrum produced when atoms absorb specific wavelengths of incoming light and become excited from lower to higher energy levels.

de Broglie wavelength

The wavelength of a moving particle obtained from the de Broglie equation: λ = h/mu.

wave-particle duality

The principle stating that both matter and energy have wavelike and particle-like properties.

uncertainty principle

The principle stated by Heisenberg that it is impossible to know simultaneously the exact position and velocity of a particle; the principle becomes important only for particles of very small mass.

quantum mechanics

The branch of physics that examines the wave nature of objects on the atomic scale.

Schodinger equation

An equation that describes how the electron matter-wave changes in space around the nucleus. Solutions of the equation provide energy states associated with the atomic orbitals.

atomic orbital (wave function)

The wave function of an electron in an atom. The term is used qualitatively to mean the region of space in which there is a high probability of finding the electron.

electron density diagram

The pictorial representation for a given energy sublevel of the quantity ψ2 (the probability density of the electron lying within a particular tiny volume) as a function of r (distance from the nucleus).

electron cloud depiction

An imaginary representation of an electron's rapidly changing position around the nucleus over time.

radial probability distribution plot

The graphic depiction of the total probability distribution (sum of ψ2) of an electron in the region near the nucleus.

probability contour

A shape that defines the volume around an atomic nucleus within which an electron spends a given percentage of its time.

principal quantum number (n)

A positive integer that specifies the energy and relative size of an atomic orbital; a number that specifies an energy level in an atom.

angular momentum quantum number (l)

An integer from 0 to n − 1 that is related to the shape of an atomic orbital

magnetic quantum number (m sub l)

An integer from −l through 0 to +l that specifies the orientation of an atomic orbital in the three-dimensional space about the nucleus.

level (shell)

A specific energy state of an atom given by the principal quantum number n.

sublevel (subshell)

An energy substate of an atom within a level. Given by the n and l values, the sublevel designates the size and shape of the atomic orbitals.

s orbital

An atomic orbital with l = 0.

p orbital

An atomic orbital with l = 1.

d orbital

An atomic orbital with l = 2.

f orbital

An atomic orbital with l = 3.

quantum numbers

n, l, ml, ms

n = principle quantum number

shell; size, energy, how many sub-shell types... 1,2,3,4,5,6...

l = angular momentum

(secondary) quantum number; subshells (s,p,d,f,g,h); energy, shape, number of nodal planes...; 0,1,2,3,4,5... to (n-1)

m subscript l

magnetic quantum number; orbitals; describes the spatial orientation of the orbital (how many boxes to draw); range from -1 to +1

m subscript s

spin quantum number; electrons; +1/2 (up arrow) for the first one, -1/2 (down arrow) for the second one.

Symbol and units for wavelength.

nm & λ

Visible light is one type of _______________radiation, which consists of energy propagated by electric and ________________fields that alternately increase and decrease in intensity as they move through space.

electromagnetic; magnetic

Correctly define, depict the symbol, and provide the units for the speed of electromagnetic radiation (light)

c = 3.00 × 108 m/s

c = λ × υ

Light moves at a constant distance per time.

Define the amplitude of a wave

The height of each crest or depth of each trough

The speed of a wave is determined by multiplying the ____________________ of the wave by its wavelength. In a vacuum all electromagnetic radiation travels at a constant speed, the speed of ______________________, which is equal to 3.00 x 108 m/s.

frequency; light

Describe the electromagnetic spectrum

All waves in the spectrum travel at the same speed in a vacuum.

The color of visible light is related to its frequency.

Symbol and units for frequency

Hz, v

The apparent bending of a wave around the edge of an object is called _____. If a wave passes through a slit that has a width of the same order of magnitude as its _____, it will bend around both edges of the slit to give a semicircular wave.

diffraction; wavelength

Waves that are in phase -

Amplitudes will add -

Waves that are out of phase -

Amplitudes will cancel -

- experience constructive interference.

- if waves are in phase.

- experience destructive interference.

- if waves are out of phase.

Energy is quantized. What does this mean?

There is a basic unit of energy that cannot be subdivided further.

Atoms, like all other matter, have specific energy levels within them. For an atom to absorb radiation, the energy of the radiation must match the energy ___________ between the two energy levels in the atoms.

difference or change

Visible light and radio waves are both examples of______________radiation, which has a dual nature, possessing the properties of both________________ and waves

electromagnetic; particles or matter

Which of the following correctly expresses energy in terms of Planck's constant? Select all that apply.

E = hν

E = hc/λ

Rutherford's nuclear model of the atom cannot exist according to classical physics because charged particles like electrons in orbit around a nucleus would continuously lose energy. The result would be that as electrons lose energy they would ______.

spiral into the nucleus to collapse the atom

Which of the following statements correctly describe the Bohr model of the hydrogen atom?

a. Only certain energy levels are allowed within the hydrogen atom.

b. The electron can move to a higher energy state by absorbing a photon with energy equal to that of the new energy state.

c. Each energy state of the hydrogen atom is associated with a fixed circular orbit of the electron around the nucleus.

d. The atom is in an excited state when the electron is in the orbit closest to the nucleus.

e. The atom is in its lowest energy state when the electron is in the orbit closest to the nucleus.

a. Only certain energy levels are allowed within the hydrogen atom.

c. Each energy state of the hydrogen atom is associated with a fixed circular orbit of the electron around the nucleus.

e. The atom is in its lowest energy state when the electron is in the orbit closest to the nucleus.

Any two waves that meet as they travel through the same medium will interact. If the two waves are in phase their crests will coincide and they will experience _____ interference, producing a wave with a(n) _____ amplitude.

constructive; increased

Correct symbol and units for wavelength

nm

λ

What quantities can be calculated from the Bohr equation for the energy levels of the hydrogen atom?

E = –2.18 × 10–18 J (1n2)1n2

-We can find the energy change of the electron moving between two levels.

-We can find the wavelength of a spectral line.

-We can find the energy needed to ionize the hydrogen atom.

Wavelength and frequency are _____ proportional to each other. As wavelength increases, frequency will _____.

inversely; decrease

The _____ of a wave is the number of wave cycles per second. This quantity is given the symbol ν and has units of s-1 or _____.

frequency; Hz

According to the Bohr model for the hydrogen atom, the energy of the atom is not continuous but has certain discrete energy_______ , each of which is related to a fixed circular_________ of the electron around the nucleus. The farther the electron is from the nucleus, the the ________ energy of the system.

Blank 1: levels, states, shells, or packets

Blank 2: orbit

Blank 3: higher, greater, or larger

Bohr developed an equation for calculating the energy levels of a hydrogen atom. Which of the following can be determined using this equation?

-The wavelength of a line in the atomic line spectrum for hydrogen

-The absolute energy of the hydrogen atom in its ground state

-The energy needed to remove an electron completely from the hydrogen atom

-The difference in energy between two energy levels in a hydrogen atom

-The energy released when two hydrogen atoms form a covalent bond

The wavelength of a line in the atomic line spectrum for hydrogen

The energy needed to remove an electron completely from the hydrogen atom

The difference in energy between two energy levels in a hydrogen atom

Wave properties are related to the amplitude of an electromagnetic wave?

Brightness (for visible light)

Intensity

Which of the following statements correctly describe the Bohr model of the hydrogen atom? Select all that apply.

Each energy state of the hydrogen atom is associated with a fixed circular orbit of the electron around the nucleus.

The atom is in its lowest energy state when the electron is in the orbit closest to the nucleus.

Only certain energy levels are allowed within the hydrogen atom.

The speed of light is the ______ of its frequency and wavelength. In a vacuum, this value is a constant, ______.

product; 3.00 × 108 m/s

All waves in the electromagnetic spectrum travel at the same _____ through a vacuum, but differ in their frequency and wavelength. A wave with a long (large) wavelength will have a _____ frequency.

speed; low

Describe the diffraction of light

Diffraction is the apparent bending of light around the edge of an object in its path.

Energy is not continuous, but is quantized or divided into "packets," each of which contains a definite amount of energy. An energy packet is called a(n) _____, and the energy of each packet is directly proportional to its _____.

quantum; frequency

Atoms, like all other matter, have specific energy levels within them. For an atom to absorb radiation, the energy of the radiation must match the energy___________ between the two energy levels in the atoms.

gap, difference, or change

Which of the following statements correctly describe the Bohr model of the hydrogen atom?

The atom is in its lowest energy state when the electron is in the orbit closest to the nucleus.

Only certain energy levels are allowed within the hydrogen atom.

Each energy state of the hydrogen atom is associated with a fixed circular orbit of the electron around the nucleus.

Which of the following correctly define, depict the symbol, and provide the units for the speed of electromagnetic radiation (light)?

Light moves at a constant distance per time.

c = λ × υ

c = 3.00 × 108 m/s

Which of the following statements correctly describe the electromagnetic spectrum?

All waves in the spectrum travel at the same speed in a vacuum.

The color of visible light is related to its frequency.

Which of the following statements correctly describes how energy is absorbed by an atom?

The energy of the absorbed radiation must match the difference between the two energy states of the atom.

Which of the following statements correctly describe the limitations of the Rutherford model of the atom?

This model could not explain why electrons did not emit energy continuously.

This model could not explain observed atomic line spectra.

Which of the following statements correctly describe wave-particle duality?

Matter and energy are different forms of the same entity.

All matter exhibits wavelike motion.

Energy and mass can be interconverted.

In the quantum-mechanical model of the atom, an electron is viewed as a wave-particle that occupies a three-dimensional space near the nucleus. The movement of the electron is described by a_______ function, which is also called an atomic_________ .

wave;orbital

The principal quantum number is given the symbol and_____________ has positive, whole-number values starting from_________________

n; 1 or one

Electrons, like all other matter, exhibit the dual behavior of both ______, Correct Unavailable and waves. Since electrons travel like waves, their energy is restricted to certain energy ______, each of which is associated with a specific wavelength.

particles; levels or states

Using the Schrodinger wave equation, we can determine the probability of finding an electron in a particular region of the atom. The electron probability density _____ with distance from the nucleus, meaning that the farther one gets from the nucleus the _____ likely it is to find an electron. (Electrons are not found within the nucleus.)

decreases; less

Heisenberg's uncertainty principle states that it is not possible to know the exact momentum and ________ of a particle simultaneously. In terms of atomic structure, this means that we cannot determine fixed ______for electrons but can only determine the path ____________of finding an electron in a given region of space.

Blank 1: position or location

Blank 2: orbits, levels, energies, paths, locations, positions, or trajectories

Blank 3: probability, likelihood, chance, or odds

True or false: The sublevels of each principal energy level of the hydrogen atom have the same energy.

True

A central concept in quantum mechanics is that both matter and ________ are alternate forms of the same entity and therefore both exhibit dual characteristics of particles and of _________. This model allows a better understanding of the behavior of tiny particles such as electrons.

energy; waves

Which of the following statements correctly describe the atom in terms of quantum mechanics?

The movement of each electron in the atom can be described by a wave function.

Each electron occupies a three-dimensional space near the nucleus. This space is described by a wave function.

Electrons exhibit behavior of both waves and particles.

Why are electrons restricted to certain, discrete energy levels within an atom?

Electrons have wavelike motion and are restricted to certain energy states associated with specific wavelengths.

Which of the following is a consequence of the Heisenberg uncertainty principle?

It is not possible to assign fixed paths for electrons.

The energy levels of the hydrogen atom depend on the value of which quantum number(s)?

n

Which of the following statements correctly describe wave-particle duality?

All matter exhibits wavelike motion.

Matter and energy are different forms of the same entity.

Energy and mass can be interconverted.

Define an atomic orbital in terms of the quantum-mechanical model of the atom

A mathematical function that describes the position of the electron-wave in three dimensions

Which of the following statements correctly describe the atom in terms of quantum mechanics?

The movement of each electron in the atom can be described by a wave function.

Electrons exhibit behavior of both waves and particles.

Each electron occupies a three-dimensional space near the nucleus. This space is described by a wave function.

True or false: The atomic orbital of the quantum-mechanical model is very similar to the orbit described by the Bohr model.

False

Reason:

Correct. An orbit in the Bohr model describes a well-defined circular path for an electron. An atomic orbital is a mathematical function with no direct physical meaning, although this function can be solved to determine regions within the atom where an electron of a particular energy is most likely to be found.

Which of the following correctly defines an atomic orbital in terms of the quantum-mechanical model of the atom?

A mathematical function that describes the position of the electron-wave in three dimensions

The principal quantum number n indicates the -

The angular momentum quantum number l indicates the -

The magnetic quantum number ml indicates the -

The relative size of the orbital is related to the value of -

The shape of the orbital is related to the value of -

- principal energy level.

- sublevel of the orbital.

- orientation of an orbital in space.

- he quantum number n.

- the quantum number l.