Elements and Compounds - AP Chemistry
Card 0 of 440
Which element has 17 electrons?
Which element has 17 electrons?
Since atoms are neutral, the number of electrons must equal the number of protons (to balance the negative and positive charges). Thus the element with 17 electrons also has 17 protons. The number of protons is equal to the atomic number of the element. Use the periodic table to find the element with atomic number 17, chlorine. Note that ions are not neutral, thus they have unequal numbers of protons and electrons. Also, isotopes of the same element contain differing numbers of neutrons, which also affects the weight of the isotope.
Since atoms are neutral, the number of electrons must equal the number of protons (to balance the negative and positive charges). Thus the element with 17 electrons also has 17 protons. The number of protons is equal to the atomic number of the element. Use the periodic table to find the element with atomic number 17, chlorine. Note that ions are not neutral, thus they have unequal numbers of protons and electrons. Also, isotopes of the same element contain differing numbers of neutrons, which also affects the weight of the isotope.
Compare your answer with the correct one above
Which of the following will result in an ion?
Which of the following will result in an ion?
Ions are atoms that have gained or lost electrons. This results in an atom with a charge. Atoms with a neutral charge have an equal number of protons and electrons. Changing the electron number will result in a charge on the atom.
For example, adding an electron to chlorine creates a chlorine anion.
Ions are atoms that have gained or lost electrons. This results in an atom with a charge. Atoms with a neutral charge have an equal number of protons and electrons. Changing the electron number will result in a charge on the atom.
For example, adding an electron to chlorine creates a chlorine anion.
Compare your answer with the correct one above
Which of the following phase labels are used for all diatomic elements?
Which of the following phase labels are used for all diatomic elements?
Diatomic elements are commonly referred to as diatomic gases because whenever they are by themselves, they bond to themselves (that is where the "2" subscript comes from). Anytime diatomic elements have that "2" subscript, they have the gas (g) phase label. For example, 
.
Diatomic elements are commonly referred to as diatomic gases because whenever they are by themselves, they bond to themselves (that is where the "2" subscript comes from). Anytime diatomic elements have that "2" subscript, they have the gas (g) phase label. For example,
Compare your answer with the correct one above
If a neutron is added to the nucleus of an atom, which of the following has changed?
If a neutron is added to the nucleus of an atom, which of the following has changed?
Isotopes are variations of an element that differ by the number of neutrons in the nucleus. Neutrons are neutrally charged, so adding or removing them from a nucleus does not alter the charge of the atom. The atomic number is the number of protons in an atom, and the mass number is the sum of both protons and neutrons in the nucleus. As a result, the mass number will change by adding a neutron.
The number of protons is equal to the atomic number of the element. Adding or subtracting protons will change the element's identity. Ions can be created by changing the number of electrons and isotopes can be created by changing the number neutrons, but changing the number of protons changes the element.
Isotopes are variations of an element that differ by the number of neutrons in the nucleus. Neutrons are neutrally charged, so adding or removing them from a nucleus does not alter the charge of the atom. The atomic number is the number of protons in an atom, and the mass number is the sum of both protons and neutrons in the nucleus. As a result, the mass number will change by adding a neutron.
The number of protons is equal to the atomic number of the element. Adding or subtracting protons will change the element's identity. Ions can be created by changing the number of electrons and isotopes can be created by changing the number neutrons, but changing the number of protons changes the element.
Compare your answer with the correct one above
Which of the following is a naturally occurring isotope of carbon-12?
Which of the following is a naturally occurring isotope of carbon-12?
Carbon is an element with six protons (atomic number six), and most commonly has six neutrons. This brings the total mass of carbon to twelve atomic mass units (12amu). There are isotopes of carbon with seven or eight neutrons, which are radioactive. These isotopes correspond to carbon-13 and carbon-14. The true atomic mass of carbon on the periodic table is 12.011amu, accounting for small contributions by these heavier isotopes.
Carbon-6, cabron-7, carbon-8, and carbon-9 imply isotopes with zero, one, two, and three neutrons respectively. Though these isotopes could theoretically exist, they would be extremely unstable and do not occur in nature.
Carbon is an element with six protons (atomic number six), and most commonly has six neutrons. This brings the total mass of carbon to twelve atomic mass units (12amu). There are isotopes of carbon with seven or eight neutrons, which are radioactive. These isotopes correspond to carbon-13 and carbon-14. The true atomic mass of carbon on the periodic table is 12.011amu, accounting for small contributions by these heavier isotopes.
Carbon-6, cabron-7, carbon-8, and carbon-9 imply isotopes with zero, one, two, and three neutrons respectively. Though these isotopes could theoretically exist, they would be extremely unstable and do not occur in nature.
Compare your answer with the correct one above
Which element is isoelectronic with a bromide ion?
Which element is isoelectronic with a bromide ion?
Two atoms are isoelectric if they each have the same number of electrons. In its ground state, bromine has 35 electrons, equal to the number of protons in order to have a neutral atom. In order to become a bromide ion, the bromine atom must gain one electron. This gives it a charge of negative one, but allows it to satisfy the octet rule, making it a very stable ion. With the ionization, the atom now has 36 electrons.
Krypton has atomic number 36, meaning that it will also have 36 electrons in its ground state.
Two atoms are isoelectric if they each have the same number of electrons. In its ground state, bromine has 35 electrons, equal to the number of protons in order to have a neutral atom. In order to become a bromide ion, the bromine atom must gain one electron. This gives it a charge of negative one, but allows it to satisfy the octet rule, making it a very stable ion. With the ionization, the atom now has 36 electrons.
Krypton has atomic number 36, meaning that it will also have 36 electrons in its ground state.
Compare your answer with the correct one above
Which of the following elements is isoelectronic with an oxygen ion?
Which of the following elements is isoelectronic with an oxygen ion?
Two atoms are isoelectric if they each have the same number of electrons. In its ground state, oxygen has 8 electrons, equal to the number of protons in order to have a neutral atom. In order to become a stable ion, the oxygen atom must gain two electrons. This gives it a charge of negative two, but allows it to satisfy the octet rule, making it a very stable ion. With the ionization, the atom now has 10 electrons.
Neon has atomic number 10, meaning that it will also have 10 electrons in its ground state.
Two atoms are isoelectric if they each have the same number of electrons. In its ground state, oxygen has 8 electrons, equal to the number of protons in order to have a neutral atom. In order to become a stable ion, the oxygen atom must gain two electrons. This gives it a charge of negative two, but allows it to satisfy the octet rule, making it a very stable ion. With the ionization, the atom now has 10 electrons.
Neon has atomic number 10, meaning that it will also have 10 electrons in its ground state.
Compare your answer with the correct one above
Which of the following elements is isoelectronic with an isotope of fluorine?
Which of the following elements is isoelectronic with an isotope of fluorine?
Two atoms are isoelectric if they each have the same number of electrons. Ions of an element will vary in the number of electrons, but isotopes will vary in the number of neutrons only. In its ground state, fluorine has 9 electrons, equal to the number of protons in order to have a neutral atom. Any ground state isotopes of fluorine will also have 9 electrons, making them isoelectric.
Two atoms are isoelectric if they each have the same number of electrons. Ions of an element will vary in the number of electrons, but isotopes will vary in the number of neutrons only. In its ground state, fluorine has 9 electrons, equal to the number of protons in order to have a neutral atom. Any ground state isotopes of fluorine will also have 9 electrons, making them isoelectric.
Compare your answer with the correct one above
Which of the following answer choices is not isoelectronic with the other atoms listed?
Which of the following answer choices is not isoelectronic with the other atoms listed?
Isoelectronic atoms are atoms or ions that contain the same number of total electrons. 
is not isoelectronic with the rest of the ions and atoms listed because it contains a total of ten electrons, while the rest in the series contain thirty-six.
Positively charged ions (cations) are formed when electrons are removed from the outer shell of the atom. Removing a negatively charged electron gives the ion a positive charge. For example, the element rubidium, 
, in its ground state contains thirty-seven electrons. The ion
contains one less, thirty-six, making it isoelectronic with krypton and the other ions and atoms in the series.
Negatively charge ions (anions) are formed when electrons are added to the outer shell of the atom. Adding a negatively charged electron gives the ion a negative charge. For example, ground state selenium, 
, contains thirty-four electrons. The ion 
, has two added electrons giving it a total of thirty-six electrons. The ion is isoelectronic with the other ions and atoms in the series.
Isoelectronic atoms are atoms or ions that contain the same number of total electrons.
Positively charged ions (cations) are formed when electrons are removed from the outer shell of the atom. Removing a negatively charged electron gives the ion a positive charge. For example, the element rubidium,
Negatively charge ions (anions) are formed when electrons are added to the outer shell of the atom. Adding a negatively charged electron gives the ion a negative charge. For example, ground state selenium,
Compare your answer with the correct one above
Which is the isotopic notation for an isotope of an element with 19 protons and 20 neutrons.
Which is the isotopic notation for an isotope of an element with 19 protons and 20 neutrons.
The general isotopic notation is as follows: 
, where 
is the mass number, which is equal to the number of neutrons plus protons, and 
is the atomic number, which is equal to the number of protons. We know that the atomic number determines the identity of an element, thus an atom with 19 protons must be potassium 
. Following the isotopic notation mentioned above, our mass number is 39.
The general isotopic notation is as follows:
Compare your answer with the correct one above
What is the isotopic notation for an isotope of an element with a mass number of 197 and 118 neutrons?
What is the isotopic notation for an isotope of an element with a mass number of 197 and 118 neutrons?
The general isotopic notation is as follows: , where is the mass number, which is equal to the number of neutrons plus protons, and is the atomic number, which is equal to the number of protons. We know that the atomic number determines the identity of an element, thus an atom with a mass number of 197 and 118 neutrons must have 79 protons. Thus the element is gold 
.
The general isotopic notation is as follows:
Compare your answer with the correct one above
Identify the number of protons, neutrons, and electrons in a 
charged cation of aluminum (mass number = 27).
Identify the number of protons, neutrons, and electrons in a
The atomic number of aluminum is 13, which means it has 13 protons. All atoms with 13 protons are called aluminum. The mass number of aluminum is 27 and is the sum of neutrons and protons. We simply subtract the number of protons from the mass number to get the number of neutrons. Normally there are an equal number of electrons and protons. But since this aluminum exists as an ion with a +3 charge, it has lost three electrons and has only 10 electrons.
The atomic number of aluminum is 13, which means it has 13 protons. All atoms with 13 protons are called aluminum. The mass number of aluminum is 27 and is the sum of neutrons and protons. We simply subtract the number of protons from the mass number to get the number of neutrons. Normally there are an equal number of electrons and protons. But since this aluminum exists as an ion with a +3 charge, it has lost three electrons and has only 10 electrons.
Compare your answer with the correct one above
What is the difference between chlorine-35 and chlorine-37?
What is the difference between chlorine-35 and chlorine-37?
Chlorine-35 and chlorine-37 are isotopes of each other. Isotopes are atoms of the same element that have different masses due to different numbers of neutrons.
Chlorine-35 and chlorine-37 are isotopes of each other. Isotopes are atoms of the same element that have different masses due to different numbers of neutrons.
Compare your answer with the correct one above
An atom of iron has two electrons removed. Write out the ion in the form of 
where X is the atomic symbol and m is the charge. Identify this ion as either a cation, anion or neutral.
An atom of iron has two electrons removed. Write out the ion in the form of
We know that the element is iron and that it is missing two electrons. This means that the atom has two less electrons than it has protons resulting in a charge of 2+. This can be written as
If an ion is positively charged it is a cation. If it is negatively charged (more electrons than protons) it is an anion.
The ion is a cation since it has a charge of 2+.
We know that the element is iron and that it is missing two electrons. This means that the atom has two less electrons than it has protons resulting in a charge of 2+. This can be written as
If an ion is positively charged it is a cation. If it is negatively charged (more electrons than protons) it is an anion.
The ion is a cation since it has a charge of 2+.
Compare your answer with the correct one above
According to molecular orbital theory, which of the following is not a valid electron configuration?
According to molecular orbital theory, which of the following is not a valid electron configuration?
We rank the order of orbital filling in order of increasing energy given the probability of an electron occupying a given space. Take into consideration the Aufbau principle, which states that electrons fill electron orbitals from most to least stable. Recall that eight electrons constitutes a full valence shell for all orbitals except for the first one, which has a maximum occupancy of two electrons. The order in which electrons are filled is as follows:
We rank the order of orbital filling in order of increasing energy given the probability of an electron occupying a given space. Take into consideration the Aufbau principle, which states that electrons fill electron orbitals from most to least stable. Recall that eight electrons constitutes a full valence shell for all orbitals except for the first one, which has a maximum occupancy of two electrons. The order in which electrons are filled is as follows:
Compare your answer with the correct one above
How many valence electrons does a fluorine atom have?
How many valence electrons does a fluorine atom have?
An atom's valence electrons are the electrons on the outermost shell surrounding the atom. For the first shell, the number of valence electrons can be at most 2. For all subsequent shells, the maximum is 8. To determine the number of valence electrons around a neutral atom, you match the atom with its group number. As you can see from the picture below, fluorine has a group number of 7. Therefore, it has 7 valence electrons.
An atom's valence electrons are the electrons on the outermost shell surrounding the atom. For the first shell, the number of valence electrons can be at most 2. For all subsequent shells, the maximum is 8. To determine the number of valence electrons around a neutral atom, you match the atom with its group number. As you can see from the picture below, fluorine has a group number of 7. Therefore, it has 7 valence electrons.
Compare your answer with the correct one above
Which of the following elements does not exist as a diatomic molecule?
Which of the following elements does not exist as a diatomic molecule?
A diatomic element is an element that will spontaneously bond with itself if it isn't already part of a compound. This is done to increase stability. The seven diatomic elements are hydrogen, oxygen, nitrogen, fluorine, chlorine, bromine, and iodine. Note that all of these except iodine are gasses at room temperature. Helium is a noble gas, which means it has a full valence shell. Helium does not need to bind to anything to increase its stability.
A diatomic element is an element that will spontaneously bond with itself if it isn't already part of a compound. This is done to increase stability. The seven diatomic elements are hydrogen, oxygen, nitrogen, fluorine, chlorine, bromine, and iodine. Note that all of these except iodine are gasses at room temperature. Helium is a noble gas, which means it has a full valence shell. Helium does not need to bind to anything to increase its stability.
Compare your answer with the correct one above
According to molecular orbital theory, which of the following is not a valid electron configuration?
According to molecular orbital theory, which of the following is not a valid electron configuration?
We rank the order of orbital filling in order of increasing energy given the probability of an electron occupying a given space. Take into consideration the Aufbau principle, which states that electrons fill electron orbitals from most to least stable. Recall that eight electrons constitutes a full valence shell for all orbitals except for the first one, which has a maximum occupancy of two electrons. The order in which electrons are filled is as follows:
We rank the order of orbital filling in order of increasing energy given the probability of an electron occupying a given space. Take into consideration the Aufbau principle, which states that electrons fill electron orbitals from most to least stable. Recall that eight electrons constitutes a full valence shell for all orbitals except for the first one, which has a maximum occupancy of two electrons. The order in which electrons are filled is as follows:
Compare your answer with the correct one above
According to molecular orbital theory, which of the following is not a valid electron configuration?
According to molecular orbital theory, which of the following is not a valid electron configuration?
We rank the order of orbital filling in order of increasing energy given the probability of an electron occupying a given space. Take into consideration the Aufbau principle, which states that electrons fill electron orbitals from most to least stable. Recall that eight electrons constitutes a full valence shell for all orbitals except for the first one, which has a maximum occupancy of two electrons. The order in which electrons are filled is as follows:
We rank the order of orbital filling in order of increasing energy given the probability of an electron occupying a given space. Take into consideration the Aufbau principle, which states that electrons fill electron orbitals from most to least stable. Recall that eight electrons constitutes a full valence shell for all orbitals except for the first one, which has a maximum occupancy of two electrons. The order in which electrons are filled is as follows:
Compare your answer with the correct one above
Which of the following quantum number sets is not possible?
Which of the following quantum number sets is not possible?
Quantum numbers are used to describe the location of an electron within the electron cloud. The first quantum number corresponds to the energy level, which matches with the period of the periodic table in which the element is usually found. The second quantum number describes the electron subshell, corresponding to the s, p, d, and f subshells. The third quantum number tells the orbital within the subshell that holds the electron. Finally, the fourth quantum number describes the spin of the electron as either positive or negative. Each orbital can only carry two electrons.
The first quantum number is a positive integer: 
The second quantum number is any integer greater than zero and less than the first quantum number: 
The third quantum number is an integer between the value of the second quantum number and its inverse: 
The final quantum number can only carry a value of positive or negative one-half: 
The answer choice that gives an impossible set of quantum numbers has a negative second quantum number. The first and second quantum numbers will always be greater than or equal to zero.
Quantum numbers are used to describe the location of an electron within the electron cloud. The first quantum number corresponds to the energy level, which matches with the period of the periodic table in which the element is usually found. The second quantum number describes the electron subshell, corresponding to the s, p, d, and f subshells. The third quantum number tells the orbital within the subshell that holds the electron. Finally, the fourth quantum number describes the spin of the electron as either positive or negative. Each orbital can only carry two electrons.
The first quantum number is a positive integer:
The second quantum number is any integer greater than zero and less than the first quantum number:
The third quantum number is an integer between the value of the second quantum number and its inverse:
The final quantum number can only carry a value of positive or negative one-half:
The answer choice that gives an impossible set of quantum numbers has a negative second quantum number. The first and second quantum numbers will always be greater than or equal to zero.
Compare your answer with the correct one above