1.
What is the general shape of an s orbital?
Correct Answer
A. SpHerical
Explanation
An s orbital is generally shaped like a sphere. This means that the electron cloud of an s orbital is symmetrical in all directions, with the highest probability of finding an electron at the center of the sphere and decreasing probability as you move away from the center. This spherical shape is a result of the mathematical equations that describe the behavior of electrons in an s orbital.
2.
A cation
Correct Answer
C. Has a positive charge
Explanation
A cation is an ion that has lost electrons, resulting in a positive charge. When an atom loses one or more electrons, it becomes positively charged because the number of protons in the nucleus is greater than the number of electrons. This positive charge makes the cation attracted to negatively charged particles, such as anions, in chemical reactions. Therefore, the correct answer is "has a positive charge."
3.
According to the Heisenberg Uncertainty Principle,
Correct Answer
C. It is impossible to know both the velocity and position of an electron.
Explanation
The Heisenberg Uncertainty Principle states that it is impossible to know both the velocity and position of an electron simultaneously. This principle arises from the wave-particle duality of electrons, where they exhibit both particle-like and wave-like properties. The more precisely we try to measure the position of an electron, the less we know about its velocity, and vice versa. This uncertainty is a fundamental aspect of quantum mechanics and has significant implications for our understanding of the behavior of subatomic particles.
4.
Which of the following atoms has the greatest ionization energy?
Correct Answer
C. Chlorine
Explanation
Chlorine has the greatest ionization energy because it is located in the upper right corner of the periodic table. As you move across a period from left to right, the ionization energy generally increases because the effective nuclear charge also increases. Chlorine has a higher effective nuclear charge compared to sulfur, silicon, and magnesium, making it more difficult to remove an electron from a chlorine atom. Therefore, chlorine has the greatest ionization energy among the given options.
5.
Which of the following would be the LEAST stable?
Correct Answer
A. An atom of N in its excited state electron configuration
Explanation
An atom of N in its excited state electron configuration would be the least stable because when an atom is in an excited state, its electrons are in higher energy levels. This means that the electrons are farther away from the nucleus and are less tightly held. As a result, the atom is more likely to react with other atoms or lose its electrons to achieve a more stable configuration. In contrast, an ion of Na+ has a stable electron configuration because it has lost one electron to achieve a full outer shell. An atom of P in its ground state electron configuration and an atom of Ar both have full outer shells, making them more stable.
6.
What is the electron configuration for selenium?
Correct Answer
B. 1s22s22p63s23p64s23d104p4
Explanation
The electron configuration for selenium is 1s22s22p63s23p64s23d104p4.
7.
The energy change associated with the gain of an electron is called
Correct Answer
D. Electron affinity
Explanation
Electron affinity refers to the energy change that occurs when an atom gains an electron. It represents the attraction between an atom and an additional electron. This energy change can be either positive or negative, depending on whether energy is released or absorbed during the process. The term "electron affinity" is commonly used in the context of chemical reactions and the study of atomic properties.
8.
What is the maximum number of sublevels in the third energy level?
Correct Answer
C. 3
Explanation
The maximum number of sublevels in an energy level can be determined by using the formula 2n^2, where n represents the principal quantum number. In this case, since it is the third energy level, the principal quantum number is 3. Plugging this value into the formula, we get 2(3)^2 = 2(9) = 18. However, the maximum number of sublevels cannot exceed the number of the energy level itself. Therefore, the maximum number of sublevels in the third energy level is 3.
9.
Which of the following atoms would have a very high electronegativity?
Correct Answer
A. Oxygen
Explanation
Oxygen would have a very high electronegativity because it is a highly electronegative element. Electronegativity is the measure of an atom's ability to attract electrons towards itself in a chemical bond. Oxygen has a strong attraction for electrons due to its high electronegativity, which makes it more likely to gain electrons and form negative ions. This property is important in determining the type of chemical bonds that oxygen can form with other elements.
10.
How will an atom of magnesium obtain an octet?
Correct Answer
A. By losing two electrons
Explanation
An atom of magnesium will obtain an octet by losing two electrons. Magnesium has two valence electrons in its outermost energy level, and by losing these two electrons, it achieves a stable configuration with a complete octet in its next energy level. This process allows magnesium to achieve a lower energy state and become more stable.
11.
How many d orbitals are found in a zinc atom?
Correct Answer
A. 5
Explanation
The number of d orbitals in an atom is determined by the principal quantum number, which is equal to the period number on the periodic table. Zinc is in period 4, so it has 4 d orbitals. However, since the d orbitals can hold a maximum of 10 electrons, only 5 d orbitals are needed to accommodate the 2 electrons in the d sublevel of a zinc atom.
12.
Which of the following elements does NOT have two valence electrons?
Correct Answer
A. Lithium
Explanation
Lithium does not have two valence electrons because it is located in Group 1 of the periodic table, meaning it has only one valence electron. Valence electrons are the electrons in the outermost energy level of an atom, and for lithium, the outermost energy level is the second energy level, which can hold a maximum of 8 electrons. Since lithium has only one electron in its outermost energy level, it does not have two valence electrons.
13.
Which of the following elements has the largest atomic radius?
Correct Answer
C. Strontium
Explanation
Strontium has the largest atomic radius among the given elements. Atomic radius is the distance from the nucleus to the outermost electron shell of an atom. As we move down a group in the periodic table, the atomic radius generally increases due to the addition of more electron shells. Strontium is located below calcium, magnesium, and beryllium in the periodic table, indicating that it has more electron shells and therefore a larger atomic radius.
14.
According to Hund's Rule,
Correct Answer
D. No orbital in a sublevel may be empty if two electrons are paired in that sublevel.
Explanation
According to Hund's Rule, when electrons are added to orbitals, they are filled in a way that maximizes the number of unpaired electrons with parallel spins. This means that if there are two electrons in a sublevel, they will occupy separate orbitals before pairing up. Therefore, no orbital in a sublevel may be empty if two electrons are paired in that sublevel.
15.
How many electrons in molybdenum are found in the fourth energy level?
Correct Answer
C. 13
Explanation
Molybdenum has an atomic number of 42, meaning it has 42 electrons. The electrons in an atom are arranged in energy levels or shells. The fourth energy level can hold a maximum of 32 electrons. Since molybdenum has 42 electrons and the first three energy levels can hold a maximum of 2, 8, and 18 electrons respectively, the remaining electrons (42 - 2 - 8 - 18 = 14) will be in the fourth energy level. Therefore, the correct answer is 13.
16.
Atoms or ions with an octet will be
Correct Answer
D. Stable.
Explanation
Atoms or ions with an octet are stable because they have a full outer electron shell. This stability is achieved by gaining, losing, or sharing electrons to reach a configuration similar to the noble gases, which have a complete outer shell. By achieving a stable electron configuration, atoms or ions can minimize their energy and increase their overall stability.
17.
An atom of silicon will have how many valence electrons?
Correct Answer
D. 4
Explanation
An atom of silicon will have 4 valence electrons. Valence electrons are the electrons in the outermost energy level of an atom, and they determine the atom's reactivity and ability to form bonds with other atoms. Silicon is in group 14 of the periodic table, which means it has 4 valence electrons.
18.
Which of the following atoms has an octet?
Correct Answer
B. Argon
Explanation
Argon has an octet. This is because argon is a noble gas and already has a full outer electron shell with eight electrons. Therefore, it does not need to gain or lose any electrons to achieve stability. Chlorine, sodium, and nickel do not have an octet as they either need to gain or lose electrons to reach a full outer shell.
19.
Which of the following elements has six valence electrons?
Correct Answer
C. Te
Explanation
Te (tellurium) has six valence electrons. The valence electrons are the electrons in the outermost energy level of an atom, and they determine the chemical properties of the element. In the case of tellurium, it is located in Group 16 of the periodic table, also known as the oxygen family. Elements in this group have six valence electrons, which is why Te is the correct answer.
20.
Which of the following atoms would have the LOWEST ionization energy?
Correct Answer
A. Lithium
Explanation
Lithium would have the lowest ionization energy because it is the furthest to the left and bottom of the periodic table among the given options. As you move from left to right across a period, the ionization energy generally increases because the atomic radius decreases and the effective nuclear charge increases. Additionally, as you move down a group, the ionization energy generally decreases because the atomic radius increases and there are more energy levels shielding the outermost electrons from the nucleus. Therefore, lithium, being at the bottom left of the periodic table, would have the lowest ionization energy among the given options.
21.
How many electrons are found in the third energy level of calcium?
Correct Answer
C. 8
Explanation
The third energy level of an atom can hold a maximum of 8 electrons. Calcium has an atomic number of 20, which means it has 20 electrons. To determine the number of electrons in the third energy level, we need to fill up the first and second energy levels first. The first energy level can hold a maximum of 2 electrons, and the second energy level can hold a maximum of 8 electrons. Therefore, the remaining 10 electrons of calcium will be found in the third energy level, with 8 electrons occupying it.
22.
What is the electron configuration for scandium?
Correct Answer
B. 1s22s22p63s23p64s23d1
Explanation
The electron configuration for scandium is 1s22s22p63s23p64s23d1. This configuration represents the distribution of electrons in the energy levels and sublevels of an atom. Scandium has 21 electrons, so the configuration starts with the filling of the 1s and 2s orbitals with 2 electrons each. Then, the 2p orbital is filled with 6 electrons. Next, the 3s and 3p orbitals are filled with a total of 8 electrons. Finally, the 4s and 3d orbitals are filled with the remaining 5 electrons, with one electron in the 3d orbital.
23.
Elements that have seven valence electrons are
Correct Answer
B. Halogens.
Explanation
Halogens are the elements that have seven valence electrons. Valence electrons are the electrons in the outermost energy level of an atom, and halogens have seven valence electrons in their outermost energy level. This makes them highly reactive and likely to gain one electron to achieve a stable electron configuration. Therefore, halogens are the correct answer to the question.
24.
Fluorine has a very high
Correct Answer
D. Electronegativity.
Explanation
Fluorine has a very high electronegativity. Electronegativity refers to the tendency of an atom to attract electrons towards itself in a chemical bond. Fluorine has the highest electronegativity value among all the elements on the periodic table. This is due to its small atomic size and high effective nuclear charge, which allows it to strongly attract electrons.
25.
What is the symbol for the gallium ion?
Correct Answer
C. Ga3+
Explanation
The symbol for the gallium ion is Ga3+. This is because gallium typically loses three electrons to form a positive ion. The superscript 3+ indicates that the ion has a charge of +3, meaning it has three more protons than electrons.
26.
Atoms are most stable when they have
Correct Answer
B. Eight valence electrons.
Explanation
Atoms are most stable when they have eight valence electrons. This is because having eight valence electrons, also known as a full outer electron shell, satisfies the octet rule. The octet rule states that atoms tend to gain, lose, or share electrons in order to achieve a stable configuration similar to the noble gases. By having a full outer electron shell, atoms are less likely to react with other atoms, making them more stable.
27.
An atom of gallium has how many electrons in its fifth energy level?
Correct Answer
D. 0
Explanation
The fifth energy level of an atom can hold a maximum of 50 electrons. However, the electron configuration of gallium (Ga) is 2-8-18-3, meaning it has 3 electrons in its outermost energy level (valence electrons). Therefore, there are no electrons in the fifth energy level of gallium.
28.
Which of the following atoms is the largest?
Correct Answer
A. Potassium
Explanation
Potassium is the largest atom among the given options. This is because the size of an atom is determined by its atomic radius, which is the distance between the nucleus and the outermost electron shell. As you move down a group in the periodic table, the atomic radius generally increases due to the addition of more electron shells. Potassium is located below sodium and magnesium in the periodic table, so it has more electron shells and a larger atomic radius, making it the largest atom among the options provided.
29.
What is the electron configuration for chlorine?
Correct Answer
A. 1s22s22p63s23p5
Explanation
The electron configuration for an atom represents the distribution of electrons in its energy levels or orbitals. In the case of chlorine, the correct electron configuration is 1s22s22p63s23p5. This means that chlorine has two electrons in the 1s orbital, two electrons in the 2s orbital, six electrons in the 2p orbital, two electrons in the 3s orbital, and five electrons in the 3p orbital.
30.
An atom of sulfur has how many valence electrons?
Correct Answer
C. 6
Explanation
Sulfur is located in group 16 of the periodic table, which means it has 6 valence electrons. Valence electrons are the electrons in the outermost energy level of an atom and are responsible for the chemical properties of an element.
31.
How many unpaired electrons are found in an atom of sulfur?
Correct Answer
C. 2
Explanation
Sulfur has an atomic number of 16, meaning it has 16 electrons. The electron configuration of sulfur is 1s2 2s2 2p6 3s2 3p4. In the outermost energy level, there are 6 electrons in the 3p orbital. In order to form stable bonds, sulfur needs 2 more electrons to complete its octet. Since there are 2 unpaired electrons in the 3p orbital, the correct answer is 2.
32.
The iodine ion will have the symbol
Correct Answer
D. I-
Explanation
The iodine ion will have the symbol I- because when iodine gains one electron, it forms a negatively charged ion. This is because iodine has seven valence electrons and needs one more electron to achieve a stable octet configuration. Therefore, the iodine ion is represented by I- to indicate the addition of one extra electron.
33.
An atom of sodium will generally tend to
Correct Answer
A. Lose one electron.
Explanation
An atom of sodium has 11 protons and 11 electrons. The outermost electron in sodium's electron configuration is in the 3s orbital. Since the outermost shell can hold a maximum of 8 electrons, sodium will generally tend to lose one electron in order to achieve a stable electron configuration, similar to that of neon which has a full outer shell. This loss of one electron results in the formation of a sodium ion with a +1 charge.
34.
An atom of iron has how many electrons in its 3d sublevel?
Correct Answer
D. 6
Explanation
An atom of iron has 6 electrons in its 3d sublevel. The electron configuration of iron is 1s2 2s2 2p6 3s2 3p6 4s2 3d6. This means that there are 6 electrons in the 3d sublevel of iron.
35.
Which of the following is a ground state electron configuration for a transition metal?
Correct Answer
A. 1s22s22p63s23p64s23d10
Explanation
The ground state electron configuration for a transition metal is characterized by having all lower energy orbitals filled before higher energy orbitals. In this case, the correct answer is 1s22s22p63s23p64s23d10 because it follows this pattern. The 1s, 2s, 2p, 3s, and 3p orbitals are filled before the 4s and 3d orbitals.
36.
When is a burst of light emitted?
Correct Answer
B. When an electron moves from an excited state to the ground state
Explanation
A burst of light is emitted when an electron moves from an excited state to the ground state. This is because when an electron is in an excited state, it has absorbed energy and is in a higher energy level. As the electron transitions back to its lower energy ground state, it releases the excess energy in the form of light. This phenomenon is known as emission of light or luminescence.
37.
Anions are always
Correct Answer
C. Negatively charged.
Explanation
Anions are negatively charged ions because they have gained one or more electrons, resulting in an excess of negative charge. This occurs when atoms of nonmetals, such as oxygen or chlorine, gain electrons to achieve a stable electron configuration. Anions play a crucial role in chemical reactions and often form compounds with cations, which are positively charged ions.
38.
How many p sublevels are found in a vanadium atom?
Correct Answer
B. 2
Explanation
The answer is 2 because the p sublevel can hold a maximum of 6 electrons and vanadium has an atomic number of 23. The electron configuration of vanadium is 1s2 2s2 2p6 3s2 3p6 4s2 3d3, indicating that there are two electrons in the p sublevel.
39.
What is the general shape of a p orbital?
Correct Answer
D. Figure-eight
Explanation
A p orbital is a three-dimensional region of space where an electron is likely to be found. It consists of two lobes, which are separated by a node. The lobes have opposite phases, meaning that one lobe has positive amplitude while the other has negative amplitude. When these two lobes are combined, they form a shape that resembles a figure-eight or an hourglass. This shape represents the probability distribution of finding an electron in a p orbital. Therefore, the correct answer is figure-eight.
40.
Which of the following is the ground state electron configuration for chromium?
Correct Answer
D. 1s22s22p63s23p64s13d5
Explanation
The electron configuration for chromium can be determined by following the Aufbau principle and Hund's rule. Chromium has an atomic number of 24, so its electron configuration starts with 1s2, 2s2, and 2p6, filling up the first three energy levels. The next electron goes into the 3s orbital, giving 1s22s22p63s2. The next six electrons fill up the 3p orbital, giving 1s22s22p63s23p6. The next two electrons go into the 4s orbital, giving 1s22s22p63s23p64s2. Finally, the remaining five electrons go into the 3d orbital, giving 1s22s22p63s23p64s13d5. Therefore, the correct answer is 1s22s22p63s23p64s13d5.
41.
Which of these elements has the greatest atomic radius?
Correct Answer
C. Xe
Explanation
Xe (Xenon) has the greatest atomic radius among the given elements. Atomic radius refers to the size of an atom, and it generally increases as you move down a group in the periodic table. Since Xe is located at the bottom of the noble gases group (Group 18), it has more energy levels and electron shielding, causing its atomic radius to be larger compared to Ar (Argon), Ne (Neon), and He (Helium).
42.
Phosphorus obtains an octet by
Correct Answer
B. Gaining three electrons.
Explanation
Phosphorus obtains an octet by gaining three electrons. This is because phosphorus has five valence electrons and needs a total of eight electrons to achieve a stable octet configuration. By gaining three electrons, phosphorus fills its outermost energy level and attains a full octet, resulting in a more stable electron configuration.
43.
Which of the following statements is true?
Correct Answer
A. Iodine has more energy levels that chlorine; therefore, iodine is larger.
Explanation
Iodine has more energy levels than chlorine, and in general, the size of an atom increases as the number of energy levels increases. This is because each energy level can hold a certain number of electrons, and as more energy levels are added, the atom becomes larger. Therefore, since iodine has more energy levels than chlorine, it is larger in size.
44.
Which of the following is the ground state electron configuration for a noble gas?
Correct Answer
C. 1s22s22p63s23p64s23d104p6
Explanation
The ground state electron configuration for a noble gas is the arrangement of electrons in the outermost energy level of the atom. The correct answer, 1s22s22p63s23p64s23d104p6, represents the electron configuration for the noble gas element, which is stable and has a full outermost energy level.
45.
How many energy levels can be found in an atom of silver?
Correct Answer
B. 5
Explanation
An atom of silver has 5 energy levels. Energy levels in an atom represent the different energy states that electrons can occupy. The first energy level can hold a maximum of 2 electrons, the second can hold a maximum of 8 electrons, the third can hold a maximum of 18 electrons, the fourth can hold a maximum of 32 electrons, and the fifth can hold a maximum of 18 electrons. Therefore, the atom of silver has 5 energy levels.