Q&A Hero

Q: Matter waves are also called ______________ waves.

Q: The concept of matter waves reflects the observation that particles such as electrons sometimes act like ______________.

Q: Black light is a common name for the region of the EMR spectrum known as ______________.

Q: Optical scanners at the grocery store often use He-Ne ______________.

Q: The energy differences in some of the rotational energy levels of the water molecule allow cooking with ______________.

Q: When an electron changes from n= 3 to n= 2, a(n) ______________ is given off.

Q: The second excited state for an electron in a hydrogen atom would be where nequals ______________.

Q: The principal quantum number is symbolized by the letter ______________.

Q: The lowest energy level of an atom (n= 1) is called the ______________.

Q: The energy of the electron in the hydrogen atom has only certain ______________ values.

Q: In common physics terminology, a particle with a negative potential energy is in a(n) potential ______________.

Q: When the energy state of an atom changes by DE, the frequency of the photon emitted or absorbed is calculated by dividing DEby ______________.

Q: Niels Bohr postulated that the hydrogen electron radiates energy only when it makes a(n) ______________ from one allowed orbit to another.

Q: Niels Bohr reasoned that a discrete line spectrum must be the result of a(n) ______________ effect.

Q: Bohr's revolutionary step in his theory was to ______________ the angular momentum of the electron.

Q: Dispersing light from a hot, low-pressure gas gives a spectrum of the type known as (two words) ______________ ______________.

Q: The n= 2 energy level is known as the (two words) ______________ ______________ state.

Q: The number of electrons in a hydrogen atom is ______________.

Q: The nucleus of an ordinary hydrogen atom consists of a(n) ______________.

Q: The color of the light in the visible region that has photons of the lowest energy is ______________.

Q: According to Planck's hypothesis, the energy of an oscillator is directly proportional to its ______________.

Q: The concept of the dual nature of light indicates that light acts sometimes like a(n) ______________ and sometimes like a(n) ______________.

Q: The quantity hin the Bohr theory is called ______________.

Q: The "particle" of light given off by an excited electron when it loses energy is called a(n) ______________.

Q: In both the Bohr model and the Schrdinger model of the atom, the letter nis called the ______________.

Q: The "billiard ball model" of the atom is associated with a scientist named ______________.

Q: Thomson discovered the ______________ in 1897.

Q: The development of physics prior to about 1900 is called ______________ physics.

Q: A quantum of electromagnetic radiation is called a(n) A) photon. B) electron. C) positron. D) proton.

Q: The nuclear model of the atom is associated with A) Thomson. B) Dalton. C) Bohr. D) Rutherford.

Q: The Bohr theory was developed to explain which of these phenomena? A) The photoelectric effect B) Line spectra C) Quantum numbers D) X-rays

Q: Theoretical limits on measurement accuracy are set by a principle associated with which scientist? A) de Broglie B) Schrdinger C) Heisenberg D) Pauli

Q: The term probabilityis associated with the model of the atom proposed by A) Schrdinger. B) Heisenberg. C) de Broglie. D) Einstein.

Q: Heisenberg's uncertainty principle states that it is impossible to know simultaneously which two properties of a particle? A) Momentum and energy B) Position and velocity C) Position and charge D) Time and place

Q: Heisenberg's uncertainty principle is most important for A) very large objects, such as the Moon. B) very large distances. C) very small particles, such as electrons. D) very small angular momentum.

Q: Glow-in-the-dark materials exhibit the phenomenon called A) phosphorescence. B) simulated absorption. C) fluorescence. D) stimulated emission.

Q: Which of the following is the de Broglie equation? A) E= mc2 B) E= hf C) mDvDxh D) l= h/mv

Q: One prediction of Einstein's special theory of relativity is that objects traveling close to the speed of light A) get lighter. B) get more massive. C) get longer. D) disappear.

Q: Einstein's special theory of relativity deals with objects that are A) being hit by X-rays. B) entering intense gravitational fields. C) moving close to the speed of light. D) being hit by energetic photons.

Q: The term stimulated emissionwould be used in explaining the operation of A) an electron microscope. B) an X-ray tube. C) a microwave oven. D) a laser.

Q: A beam of laser light is A) neither monochromatic nor coherent. B) monochromatic but not coherent. C) coherent but not monochromatic. D) both monochromatic and coherent.

Q: When a hydrogen electron is in its first excited state, its principal quantum number isA) zero.B) 2.C) -13.60 eV.D) 1.

Q: When an electron in an atom moves from a lower energy level to a higher one, a ______________ is ______________. A) photon; emitted B) proton; emitted C) photon; absorbed D) proton; absorbed

Q: Charged particles from the Sun enter Earth's atmosphere close to the magnetic poles and cause A) global cooling. B) global warming. C) auroras. D) ozone depletion.

Q: Which element was detected in the Sun before it was found on Earth? A) Hydrogen B) Promethium C) Helium D) Argon

Q: For a specific element, photons of how many different energies could be absorbed by electrons to jump from the n= 1 to n= 3 level? A) 6 B) 3 C) 4 D) 1 E) 2

Q: For a specific element, photons of how many different energies could be emitted by electrons in the n= 4 level as they return to the n= 1 level? A) 3 B) 5 C) 2 D) 6

Q: Dispersing light from a gas-discharge tube produces what type of spectrum? A) Ultraviolet B) Line absorption C) Continuous D) Line emission

Q: When a hydrogen atom's electron goes from an energy state of n= 6 to n = 1, A) the radius of the electron's orbit is unchanged. B) the radius of the electron's orbit is increased. C) the radius of the electron's orbit is decreased. D) the radius of the electron's orbit is infinite.

Q: When a hydrogen atom's electron goes from an energy state of n = 1 to n= 3, A) the radius of the electron's orbit is unchanged. B) the radius of the electron's orbit is increased. C) the radius of the electron's orbit is decreased. D) the radius of the electron's orbit is infinite.

Q: Calculate the radius in nanometers of the orbit of a hydrogen atom's electron with n= 5. A) 0.27 B) 2.7 C) 1.3 D) 0.13

Q: According to the Bohr theory, the probability of finding a hydrogen atom's ground-state electron 0.053 nm from the proton is A) low, but not zero. B) 100%. C) zero. D) high, but not 100%.

Q: According to the Schrdinger equation, the probability of finding a hydrogen atom's ground-state electron 0.053 nm from the proton is A) zero. B) high, but not 100%. C) low, but not zero. D) 100%.

Q: Which phenomenon shows that quanta of light, or photons, exist? A) Diffraction B) Polarization C) The photoelectric effect D) Interference

Q: The development of physics prior to 1900 is called A) classical physics. B) neoclassical physics. C) Galilean physics. D) ancient physics.

Q: Addition of an electron to an atom gives a A) negative ion. B) neutron. C) new element. D) positive ion.

Q: Which is another name for quantum mechanics? A) Classical mechanics B) Wave mechanics C) Optical mechanics D) Spherical mechanics

Q: The dilemma known as the ultraviolet catastrophe was resolved in 1900 by A) Bohr. B) Rutherford. C) Einstein. D) Planck.

Q: The planetary model of the atom is associated with A) Bohr. B) Thomson. C) Dalton. D) Rutherford.

Q: The unit called the hertz (Hz) is equivalent to A) 1/s only. B) a reciprocal second only. C) s-1 only. D) all of these.

Q: Tripling the wavelength of a photon would ______________. A) reduce its energy to one-third B) triple its energy C) quadruple its energy D) not change

Q: Doubling the wavelength of a photon would ______________ its energy. A) halve B) double C) quadruple D) not change

Q: The smaller the frequency of light, the smaller the ______________ of its photons. A) wavelength B) speed C) mass D) energy

Q: With which object would the wave nature of matter be significant? A) A hard-thrown baseball B) A speeding truck C) A moving electron D) An orbiting planet

Q: Which of these instruments is based on the theory of matter waves? A) Microwave oven B) X-ray tube C) Electron microscope D) Cathode ray tube

Q: The de Broglie wavelength of a particle is inversely proportional to both its speed and its A) spin. B) electric charge. C) volume. D) mass.

Q: Calculate the de Broglie wavelength for an electron (m= 1 10-30 kg) moving at 3.3 106m/s.A) 1.7 x 10-10mB) 2.2 x 10-10mC) 1.8 x 10-10mD) 2.0 x 10-10m

Q: Who, in 1925, postulated that matter, as well as light, has properties of both waves and particles? A) Planck B) Heisenberg C) de Broglie D) Einstein

Q: Matter waves were confirmed when it was found that electrons A) diffract. B) have a plus or minus spin quantum number. C) possess a negative charge. D) have mass.

Q: As the speed of an object decreases, its wavelength A) remains unchanged. B) decreases. C) increases. D) is zero.

Q: As the speed of an object increases, its wavelength A) remains unchanged. B) decreases. C) increases. D) is zero.

Q: According to the hypothesis of de Broglie, any moving particle has A) energy. B) a magnetic force field. C) an electric force field. D) a wavelength.

Q: The key process of a laser is A) stimulated emission. B) Bremsstrahlung. C) electron diffraction. D) microwave absorption.

Q: When many of the atoms or molecules in a sample have been excited into a metastable state, a(n) ______________ has occurred. A) ultraviolet catastrophe B) population inversion C) coherent emission D) incoherent absorption

Q: When fast electrons strike a metal target, what are produced? A) Radio waves B) Gamma rays C) X-rays D) Microwaves

Q: Wilhelm Roentgen discovered A) X-rays. B) gamma rays. C) radio waves. D) microwaves.

Q: The interior of a large mass of food in a microwave oven must be heated mainly by A) radiation. B) conduction. C) convection. D) radioactivity.

Q: The energy differences in some of the rotational energy levels of the water molecule allow A) X-rays to be produced. B) cooking with microwaves. C) visible spectral lines to be formed. D) lasers to operate.

Q: Which of the following principal quantum number values is impossible? A) 2.5 B) 16 C) 3 D) 1

Q: An electron is in its lowest energy level when A) it is free of nuclear forces. B) its momentum is zero. C) it is in its ground state. D) none of these.