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11 Cards in this Set
- Front
- Back
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When a single atom gains or loses electrons, an ion forms. This is the only way an ion can form in nature. True or False?
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False. When a single atom gains or loses electrons, an ion forms. That is not, however, the only way that an ion can form in nature. It turns out that several atoms can come together and gain or lose electrons as a group. Since these ions require more than one atom, we call them polyatomic ions.
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When an ion ends with an oxygen, its name usually starts with the first atom in the ion and ends in _________ or _______.
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“ate” or “ite.”
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For a certain starting atom, the ion with more oxygens has the ______ ending, while the one with fewer oxygen atoms has the _____ ending.
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For a certain starting atom, the ion with more oxygens has the “ate” ending, while the one with fewer oxygen atoms has the “ite” ending.
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Why are there parentheses in the following chemical formula?
(NH^4)^2SO^4 |
They emphasize that this ionic compound has two ammonium ions (NH^4+) in it.
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Give the chemical formula for the following compound:
potassium sulfate |
The name tells us that this substance is composed of the potassium ion and the sulfate ion. The periodic chart tells us that the potassium ion has a charge of 1+, while we should have the sulfate ion memorized as having a 2- charge. Ignoring the signs and switching the numbers, we get:
K^2SO^4 No parentheses are needed here because there is only one sulfate ion. |
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Give the chemical formula for the following compound:
ammonium carbonate |
The name tells us that this substance is composed of the ammonium ion and the carbonate ion. Our memory tells us that the ammonium ion has a 1+ charge, and the carbonate ion has a 2- charge. Ignoring the signs and switching the numbers, we get:
(NH4)^2CO^3 No parentheses are needed for the carbonate ion because there is only one. However, since there are two ammonium ions, we must have parentheses around the NH^4. |
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Give the chemical formula for the following compound:
aluminum acetate |
The name tells us that this substance is composed of the aluminum ion and the acetate ion. The periodic chart tells us that the aluminum ion has a charge of 3+, while we should have the acetate ion memorized as having a 1- charge. Ignoring the signs and switching the numbers, we get:
Al(C^2H^3O^2)^3 |
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Remember that the dashes in this Lewis structure represent covalent bonds. Remember also that these covalent bonds are just electron pairs that are shared between two atoms. Well, since each of these covalent bonds is made up of electron pairs, we can easily predict something about their behavior. What will they tend to do?
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They will tend to repel one another, because they each have the same type of electrical charge.
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Why are the bonds in a two-dimensional structure different for the bonds in a three-dimensional structure? (Use CH^4 in your explanation)
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As a flat, two-dimensional structure, the bonds between the C and H cannot get any farther apart from one another than 90 degrees. However, if the molecule takes advantage of three-dimensional space, the bonds can spread out a bit more. It turns out that the bonds can get as far as 109 degrees from each other in a three-dimensional structure
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Two-dimensional Lewis structures have sticks to indicate bonds. What do three-dimensional structures use?
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They use solid, dashed, and triangular lines. The solid lines represent chemical bonds that are in the plane of the paper. (in a two dimensional drawing if you were to try and draw it three dimensionally) The dashed line, however, is supposed to indicate a bond that goes behind the plane of the paper. Finally, the heavy, triangular line represents a chemical bond that is out in front of the plane of the paper.
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The three shapes we have considered so far are all built on the framework of a tetrahedron. The pyramidal shape is just a tetrahedron with one leg removed, while the bent shape is a tetrahedron with two legs removed. Why do these particular shapes exist?
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This tetrahedron framework exists because in the three molecules we have considered so far, the central atom has four groups of electrons around it.
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