Chemistry 103: Unit 2 Test Review

Wavelength

The spatial distance between two consecutive identical points, such as from peak to peak

Amplitude

Measure of intensity or brightness

Frequency

The number of full wave cycles that pass a fixed point in one second

Inversely

Wavelength and frequency are __________ related.

wavelength = c/v

What is the equation for wavelength?

Speed of light

What does the constant c stand for?

3.0e8 m/s

What is the speed of light, c?

0.10 nm

What is the wavelength of an x-ray with a frequency of 3.0e18 Hz?

Diffraction

Process where waves bend around obstacles or spread out after passing through small openings

Constructive Interference

What is it called when waves are in-phase and the crests and troughs reinforce each other, creating a larger wave?

Destructive Interference

What is it called when waves are out-of-phase and the crests and troughs cancel each other out?

True

True/False: The energy of a light wave does not depend on the amplitude of the wave?

Photoelectric effect

Phenomenon that occurs when electromagnetic radiation shines on a metal surface and electrons are emitted

Electrons

In the photoelectric effect, light transfers its energy directly to the what at the metal surface?

Attractive electrostatic

In the photoelectric effect, a portion of the energy from light is used to overcome ________________ forces holding the electron to its nucleus.

Kinetic Energy

In the photoelectric effect, what is leftover energy transformed into to accelerate the freed electron away from the metal?

The speed of the electrons increases

Electrons are ejected when a metal is irradiated with light. What happens if the frequency of the light is increased (wavelength is decreased)?

More electrons are emitted

Electrons are ejected when a metal is irradiated with light with a wavelength of 458 nm. What happens if the intensity (amplitude) of the light increased?

True

True/False: In the photoelectric effect, no electrons are emitted below a certain frequency of light (threshold frequency) regardless of the intensity.

Increases

Above the threshold frequency, the kinetic energy (speed) of electrons __________ linearly with light frequency.

Photons

Light is a stream of discrete energy packets called what?

One

One photon interacts with how many electrons?

Frequency

The energy of a photon depends strictly on its what?

Ephoton = hv

What is the equation for the energy of a photon?

Planck’s constant

What does h stand for?

6.626e-34 Js

What is the numerical value of Planck’s constant?

2.6e-15 J

What is the energy of an x-ray photon with a frequency of 4.0e18 Hz?

More electrons

In the photoelectric effect, increasing light intensity results in ______________ emitted with the same kinetic energy.

Kinetic energy

In the photoelectric effect, increasing light frequency beyond the threshold frequency results in an increase in the maximum ___________ of the emitted electrons.

Frequency, wavelength

The energy of a photon is directly proportional to its __________ and inversely proportional to its ____________.

Ephoton = hv = hc/wavelength

What is the equation for the energy of a photon, including its inverse equation?

280 nm

Light delivers energy. With high enough photon energy, chemical bonds can be broken. Breaking a covalent bond between two hydrogen atoms in an H2 molecule requires 7.2e-19 J of energy. What wavelength of light does this correspond to?

False

True/False: Atoms cannot emit light.

False

True/False: Atoms cannot absorb light.

True

True/False: The wavelengths of light absorbed and emitted by hydrogen are the same.

Definite

According to Bohr’s model, electrons move in orbits around the nucleus with ________ energies and at _________ distances from the nucleus.

Photons

According to Bohr’s model, ________ are emitted/absorbed by atoms as electrons move from one energy level to another.

Absorbed

An electron moves to a higher energy orbit when a photon is what?

Emitted

A photon is ________ when an electron drops to a lower energy orbit.

Difference

According to Bohr’s model, the energy of the photons corresponds to the __________ in energy between the orbits.

10.2 eV

How much energy must be absorbed to transition an electron from n=1 to n=2 in a hydrogen atom? n=1 → -13.6 eV and n=2 → -3.4 eV

121.4 nm

What wavelength of light must be absorbed to transition an electron from n=1 to n=2 in a hydrogen atom? (1 eV = 1.6e-19 J; h = 6.626e-34 Js; c = 2.998e8 m/s)

13.6 eV

How much energy is required to completely remove the electron in a hydrogen atom? (n=1 → -13.6 eV)

False

True/False: Absorption and emission can result in the ejection of an electron from the atom.

Ionization

What is the process that occurs when an electron leaves an atom?

Davisson and Germer Experiment

What experiment disproved the idea that electrons were just tiny solid particles?

Diffraction

During the Davisson and Germer Experiment, what kind of pattern was observed when electrons were shot at a nickel crystal?

Double Slit Experiment with Electrons

What experiment proved that electrons travel as waves?

Interference

During the double slit experiment, it was observed that the electrons formed an ____________ pattern of alternating bright and dark bands.

Wavelength = h/mv

What is the equation for wave-particle duality?

Mass (kg)

In the wave-particle duality equation, what does m stand for?

Velocity (m/s)

In the wave-particle duality equation, what does v stand for?

Planck’s Constant

In the wave-particle duality equation, what does h stand for?

Certain

With large objects, the object position is __________.

Uncertain

With small objects, the object position is __________.

Small

Large objects have __________ wavelengths.

Large

Small objects have __________ wavelengths.

0.165 nm

In the Davisson-Germer experiment, electrons were accelerated by a potential of 54 V to a speed of 4.4e6 m/s. Calculate the de Broglie wavelength of these electrons in nanometers. (h = 6.626e-34 Js; mass of an electron = 9.109e-31 kg; 1J = 1kg x m²/s²)

Macroscopic

Wave-particle duality is invisible to us at a __________ scale, but it governs everything at very small scales.

1s atomic orbital

The spherical boundary that encompasses 90% of the dots represents the ________________ of the H atom.

Atomic orbitals

What are the mathematical solutions to the Schrödinger wave equations?

Three-dimensional

The solutions to the Schrödinger wave equation describe electrons vibrating in place as _____________ standing waves.

True

True/False: More nodes means shorter wavelengths, higher frequencies, and higher energies

Spherical

What shape are s orbitals?

Dumbbell

What shape are p orbitals?

Cloverleaf

What shape are most d orbitals?

One

How many s orbitals are there for a given n?

Three

How many p orbitals are in a subshell?

Five

How many d orbitals are in a subshell?

1

How many radial nodes do s orbitals contain?

1, 2

How many planar nodes do p orbitals contain? How many radial nodes to p orbitals contain?

2, 3

How many planar nodes do d orbitals contain? How many radial nodes do d orbitals contain?

0%

What is the probability of finding a 2p electron within a planar node?

1 radial node, 1 planar node

How many radial and planar nodes are in the 3p orbital shown?

Subshell

A group of atomic orbitals constitutes a what?

Shell or principle energy level

A group of subshells constitutes a what?

n²

A shell contains a total of how many orbitals?

9

What is the total number of atomic orbitals in the n=3 shell?

Two

An external magnetic field forces the electron’s intrinsic magnetic moment into how many distinct energy states?

+1/2 (spin up)

What energy state aligns with the external magnetic field?

-1/2 (spin down)

What energy state aligns against the external magnetic field?

False

True/False: For elements with more than one electron, orbitals with the same energy level have the same energy.

Pauli Exclusion Principle

What principle states that electrons can share the same orbital, but only if they have opposite signs?

Aufbau Principle

What principle states that electrons fill the lowest energy orbitals first?

Hund’s Rule

What rule states that electrons fill degenerate (equal energy) orbitals singly with parallel spins before pairing up?

What is the orbital box diagram for a beryllium atom in the ground (lowest energy) state?

What is the orbital box diagram for a carbon atom in the ground state?

[Ne] 3s² 3p³

What is the condensed electron configuration for a phosphorus atom in the ground state?

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p¹, 13

What is the electron configuration for a gallium (Ga) atom in the ground state? How many total electrons are in p-orbitals?

Core electrons

What kind of electrons inhabit the inner shells closest to the nucleus and are tightly bound by a strong nuclear pull?