GRE Subject Test: Chemistry › Molecules and Compounds
Which of the following molecules contains the shortest bond between nitrogen and oxygen?
This question is testing your ability to draw Lewis dot structures and your knowledge of how resonance effects bond length. The N-O bond with the greatest pi-bond character will be the shortest; thus, we are looking for a double- or triple-bond between nitrogen and oxygen.
Hydroxylamine () only contains single bonds, which have the least pi-bond character.
The nitrite and nitrate ions both have a double bond between the nitrogen and oxygen, but also one or more single bonds between these elements. This means that, because of resonance, the N-O bonds in these molecules will be averaged and our average bond order will be somewhere between single and double. Nitrate will have one double bond and two single bonds, for an average bond order of 1.33. Nitrite has one single bond and one double bond, for a bond order of 1.5.
The nitrosyl ion, however, will contain a triple bonds between the nitrogen and oxygen atoms, giving it the greatest pi-bond character. This bond will contain more energy and be shorter than the bonds in the other answer options.
Which of the following molecules contains the shortest bond between nitrogen and oxygen?
This question is testing your ability to draw Lewis dot structures and your knowledge of how resonance effects bond length. The N-O bond with the greatest pi-bond character will be the shortest; thus, we are looking for a double- or triple-bond between nitrogen and oxygen.
Hydroxylamine () only contains single bonds, which have the least pi-bond character.
The nitrite and nitrate ions both have a double bond between the nitrogen and oxygen, but also one or more single bonds between these elements. This means that, because of resonance, the N-O bonds in these molecules will be averaged and our average bond order will be somewhere between single and double. Nitrate will have one double bond and two single bonds, for an average bond order of 1.33. Nitrite has one single bond and one double bond, for a bond order of 1.5.
The nitrosyl ion, however, will contain a triple bonds between the nitrogen and oxygen atoms, giving it the greatest pi-bond character. This bond will contain more energy and be shorter than the bonds in the other answer options.
Which of the following molecules contains the shortest bond between nitrogen and oxygen?
This question is testing your ability to draw Lewis dot structures and your knowledge of how resonance effects bond length. The N-O bond with the greatest pi-bond character will be the shortest; thus, we are looking for a double- or triple-bond between nitrogen and oxygen.
Hydroxylamine () only contains single bonds, which have the least pi-bond character.
The nitrite and nitrate ions both have a double bond between the nitrogen and oxygen, but also one or more single bonds between these elements. This means that, because of resonance, the N-O bonds in these molecules will be averaged and our average bond order will be somewhere between single and double. Nitrate will have one double bond and two single bonds, for an average bond order of 1.33. Nitrite has one single bond and one double bond, for a bond order of 1.5.
The nitrosyl ion, however, will contain a triple bonds between the nitrogen and oxygen atoms, giving it the greatest pi-bond character. This bond will contain more energy and be shorter than the bonds in the other answer options.
Which is not a property of covalent compounds?
The elements involved generally have large differences in electronegativity
They have low melting and boiling points
They are poor electrical conductors
Many are not soluble in water, but are soluble in nonpolar liquids
They contain bonds formed by sharing one or more pairs of valence electrons between atoms
The incorrect statement is a property of ionic compounds rather than covalent. Recall that electronegativity is a measure of the ability of an atom to draw electrons to itself. Ionic compounds are formed by elements with very different electronegativities, since elements with different electronegativities will tend to form positive and negative ions (that is, they give away or gain electrons easily). In contrast, covalent bonds are formed by elements which are close in electronegativity and could exist as stable free molecules. All other statements are true of covalent compounds.
Which is not a property of covalent compounds?
The elements involved generally have large differences in electronegativity
They have low melting and boiling points
They are poor electrical conductors
Many are not soluble in water, but are soluble in nonpolar liquids
They contain bonds formed by sharing one or more pairs of valence electrons between atoms
The incorrect statement is a property of ionic compounds rather than covalent. Recall that electronegativity is a measure of the ability of an atom to draw electrons to itself. Ionic compounds are formed by elements with very different electronegativities, since elements with different electronegativities will tend to form positive and negative ions (that is, they give away or gain electrons easily). In contrast, covalent bonds are formed by elements which are close in electronegativity and could exist as stable free molecules. All other statements are true of covalent compounds.
Which is not a property of covalent compounds?
The elements involved generally have large differences in electronegativity
They have low melting and boiling points
They are poor electrical conductors
Many are not soluble in water, but are soluble in nonpolar liquids
They contain bonds formed by sharing one or more pairs of valence electrons between atoms
The incorrect statement is a property of ionic compounds rather than covalent. Recall that electronegativity is a measure of the ability of an atom to draw electrons to itself. Ionic compounds are formed by elements with very different electronegativities, since elements with different electronegativities will tend to form positive and negative ions (that is, they give away or gain electrons easily). In contrast, covalent bonds are formed by elements which are close in electronegativity and could exist as stable free molecules. All other statements are true of covalent compounds.
Given the salt , what is the charge on the
ion in this molecule?
In order to determine the charge of the ion in the molecule,
, we must first determine the net charge of the molecules it is bonded to. The
ion is bonded to a
ions.
ion is one a common anion and carries a -2 charge. Molecules like to exist in their most stable state which gives them an overall charge of zero.
has an overall charge of zero. Therefore, the
atom will carry a charge of +2 to counter the -2 charge from the
ion.
Given the salt , what is the charge on the
ion in this molecule?
In order to determine the charge of the ion in the molecule,
, we must first determine the net charge of the molecules it is bonded to. The
ion is bonded to a
ions.
ion is one a common anion and carries a -2 charge. Molecules like to exist in their most stable state which gives them an overall charge of zero.
has an overall charge of zero. Therefore, the
atom will carry a charge of +2 to counter the -2 charge from the
ion.
Given the salt , what is the charge on the
ion in this molecule?
In order to determine the charge of the ion in the molecule,
, we must first determine the net charge of the molecules it is bonded to. The
ion is bonded to a
ions.
ion is one a common anion and carries a -2 charge. Molecules like to exist in their most stable state which gives them an overall charge of zero.
has an overall charge of zero. Therefore, the
atom will carry a charge of +2 to counter the -2 charge from the
ion.
For the compound shown below, the hybridization for carbon A is __________ and the hybridization for carbon B is __________.
Carbon Ais hybridized because this carbon is only bonded to two other atoms. Carbon B is bonded to four atoms, and would therefore be
hybridized.
Keep in mind that a carbon involved in a triple bond will always be hybridized, a carbon involved in a double bond will be
hybridized, and a carbon involved only in single bonds will be
hybridized.