1.
Small packets of energy that are given off are called _________.
Correct Answer
B. Quanta
Explanation
Small packets of energy that are given off are called quanta. This term is often used in quantum physics to describe the discrete units in which energy is emitted or absorbed. Photons, on the other hand, are particles of light that can be considered as quanta of electromagnetic energy. Waves, although they can carry energy, do not refer specifically to small packets of energy like quanta do.
2.
What refers to the phenomenon in which electrons are emitted from the surface of a metal when light strikes it?
Correct Answer
C. pHotoelectric effect
Explanation
The phenomenon in which electrons are emitted from the surface of a metal when light strikes it is known as the photoelectric effect. This effect occurs when photons of light transfer their energy to electrons in the metal, causing them to be ejected. The photoelectric effect was first explained by Albert Einstein and is a fundamental concept in understanding the behavior of light and electrons. Planck's constant is related to the energy of photons, while the dual nature of light refers to its wave-particle duality.
3.
What results when light is scattered from a regular array of points or lines?
Correct Answer
A. Diffraction
Explanation
When light is scattered from a regular array of points or lines, it results in diffraction. Diffraction is the bending or spreading of light waves as they pass through an opening or around an obstacle. This phenomenon occurs when the size of the opening or obstacle is similar to the wavelength of the light. The regular array of points or lines acts as a diffraction grating, causing the light to diffract and create a pattern of interference. This can be observed as a spectrum of colors or a pattern of bright and dark fringes.
4.
Does a photon really have mass?
Correct Answer
A. Yes
Explanation
Yes, a photon does have mass. According to the theory of relativity, any object with energy has mass. Photons are particles of light and they carry energy, therefore they have mass. However, their mass is incredibly small and they are considered to be massless in many practical situations.
5.
Who devised the equation that allows us to calculate the wavelength for a particle?
Correct Answer
B. Louis de Broglie
Explanation
Louis de Broglie is credited with formulating the concept of wave-particle duality, which states that particles can exhibit both wave-like and particle-like properties. He proposed that all particles, including matter, have a wave nature associated with them. This idea was revolutionary and laid the foundation for the development of quantum mechanics. De Broglie's equation, known as the de Broglie wavelength equation, allows us to calculate the wavelength associated with a particle based on its momentum. Therefore, it is accurate to say that Louis de Broglie devised the equation that allows us to calculate the wavelength for a particle.
6.
Who proposed that "the electron in a hydrogen atom moves around the nucleus only in certain allowed circular orbits"?
Correct Answer
A. Niels Bohr
Explanation
Niels Bohr proposed that "the electron in a hydrogen atom moves around the nucleus only in certain allowed circular orbits." Bohr's model of the atom, known as the Bohr model, revolutionized our understanding of atomic structure. He suggested that electrons occupy specific energy levels or orbits, and they can move between these levels by absorbing or emitting energy in discrete amounts. This idea laid the foundation for the development of quantum mechanics and provided a framework for explaining atomic spectra and the stability of atoms.
7.
The lowest possible energy state of an electron is called what?
Correct Answer
B. Ground state
Explanation
The ground state refers to the lowest energy level that an electron can occupy in an atom. In this state, the electron is in its most stable configuration, closest to the nucleus. Excited states, on the other hand, refer to higher energy levels where electrons have absorbed energy and moved to a higher orbital. The quantum model is a broader concept that encompasses the understanding of electron behavior and energy levels based on quantum mechanics.
8.
Where were fireworks first created and used?
Correct Answer
C. China
Explanation
Fireworks were first created and used in China. The Chinese are credited with inventing fireworks around 2,000 years ago. The earliest form of fireworks was made by mixing sulfur, charcoal, and saltpeter (potassium nitrate). These ingredients were packed into bamboo tubes and ignited to produce colorful explosions. The Chinese initially used fireworks for religious and ceremonial purposes, such as warding off evil spirits and celebrating important events. The knowledge of fireworks then spread to other parts of the world through trade and exploration.
9.
According to the Heisenberg uncertainty principle, we cannot simultaneously know a particle's position and _________.
Correct Answer
C. Momentum
Explanation
According to the Heisenberg uncertainty principle, we cannot simultaneously know a particle's position and momentum. This principle states that there is a fundamental limit to the precision with which certain pairs of physical properties of a particle, such as position and momentum, can be known. The more precisely we try to measure one property, the less precisely we can measure the other. Therefore, if we have precise knowledge of a particle's position, its momentum becomes uncertain, and vice versa.
10.
Which quantum number is related to the shape of an atomic orbital?
Correct Answer
B. Angular momentum
Explanation
The quantum number related to the shape of an atomic orbital is the angular momentum quantum number. This quantum number determines the orbital shape and describes the subshell in which the electron is located. The different values of the angular momentum quantum number correspond to different orbital shapes, such as s, p, d, and f orbitals.
11.
The electron spin quantum number states that electrons can spin in __________ directions.
Correct Answer
A. Opposite
Explanation
The electron spin quantum number states that electrons can spin in opposite directions. This means that electrons can either have a spin-up or spin-down orientation. The opposite spin direction allows for the formation of electron pairs in atomic orbitals, which is a fundamental concept in understanding chemical bonding and the stability of atoms.
12.
What important concept states that "an orbital can hold only two electrons, and they must have opposite spins"?
Correct Answer
C. Pauli exclusion principle
Explanation
The Pauli exclusion principle states that in an orbital, only two electrons can be present and they must have opposite spins. This principle is a fundamental concept in quantum mechanics and helps to explain the arrangement of electrons in atoms. It ensures that no two electrons in an atom can have the same set of quantum numbers, which ultimately determines the electronic configuration of an atom.
13.
What important concept states that "as protons are added one by one to the nucleus to build up the elements, electrons are similarly added to these hydrogenlike orbitals"?
Correct Answer
A. Aufbau principle
Explanation
The Aufbau principle is an important concept in chemistry that states that as protons are added one by one to the nucleus to build up the elements, electrons are similarly added to these hydrogenlike orbitals. This principle helps to explain the order in which electrons fill the energy levels and sublevels of an atom. It states that lower energy levels and sublevels are filled before higher energy levels and sublevels. This principle is essential for understanding the electron configuration and the periodic table.
14.
What important concept states "the lowest energy configuration for an atom is the one having the maximum number of unpaired electrons allowed by the Pauli principle in a particular set of degenerate orbitals"?
Correct Answer
C. Hund's rule
Explanation
Hund's rule states that the lowest energy configuration for an atom is the one with the maximum number of unpaired electrons allowed by the Pauli principle in a specific set of degenerate orbitals. This means that when filling orbitals of the same energy level, electrons will occupy separate orbitals with the same spin before pairing up. This rule helps to explain the observed electron configurations of atoms and their stability.
15.
What are the electrons in the outermost principal quantum level of an atom called?
Correct Answer
B. Valence
Explanation
The electrons in the outermost principal quantum level of an atom are called valence electrons. These electrons are involved in chemical reactions and determine the atom's reactivity and ability to form bonds with other atoms. Valence electrons are important in understanding the behavior of elements and their ability to form compounds.
16.
What is the energy required to remove an electron called?
Correct Answer
B. Ionization energy
Explanation
Ionization energy is the energy required to remove an electron from an atom or ion in its gaseous state. When an electron is removed, the resulting species becomes positively charged. Ionization energy is a measure of how strongly an atom holds onto its electrons. It is an important concept in chemistry as it helps in understanding the reactivity and stability of elements and compounds.
17.
What is the energy change associated with the addition of an electron to an atom?
Correct Answer
A. Electron affinity
Explanation
The energy change associated with the addition of an electron to an atom is known as electron affinity. Electron affinity is a measure of how much an atom wants to gain an electron. It is the energy released when an electron is added to a neutral atom to form a negative ion. A higher electron affinity indicates a stronger attraction for electrons, while a lower electron affinity indicates a weaker attraction.
18.
The quantum mechanical model of the atom has allowed us to understand the basis for the similarity of properties in a group -- that each group member has the same __________.
Correct Answer
C. Valence electron configuration
Explanation
The quantum mechanical model of the atom describes the arrangement of electrons in an atom. It explains that the outermost electrons, known as valence electrons, determine the chemical properties of an element. These valence electrons are responsible for the bonding and reactivity of elements. Therefore, each group member in the periodic table has the same valence electron configuration, which leads to similar chemical properties within a group. This understanding has been made possible by the quantum mechanical model of the atom.