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92 Cards in this Set
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- Back
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The electron configuration of bromine:
1s*2 2s*2 2p*6 3s*2 3p*6 4s*2 3d*10 4p*5 What does this configuration tell a chemist in regards to how many electrons, how many different orbitals, and how many different distances from the nucleus? |
There are 35 electrons (add superscripts), and they are all whirling around the nucleus. The electron configuration tells us that they are whirling about in three different orbital shapes (because s, p, and d orbitals are all present) and at four different distances from the nucleus (since energy levels 1-4 are present).
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When forming molecules, the only important part of the atom is its electrons. Which electrons are the most important?
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The nucleus of the atom plays no role whatsoever in making the molecule. In fact, not even all of the electrons are important.
The only electrons that significantly affect the chemistry of an atom are those that are farthest away from the nucleus. Those are the electrons that will begin to interact with another atom's electrons. |
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The electron configuration of bromine:
1s*2 2s*2 2p*6 3s*2 3p*6 4s*2 3d*10 4p*5 If you look at the electron configuration for bromine, which electrons are the farthest away from the nucleus? |
Well, in bromine's electron configuration, energy levels 1-4 are present. According to what we learned in the last module, the larger the energy level's number, the farther it is from the nucleus. Therefore, the electrons in energy level 4 are the ones that are farthest from the nucleus. These are the ones that will affect the chemistry of bromine. Although the electrons in energy levels 1-3 are present, they do little to affect the way in which bromine behaves chemically.
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The electron configuration of bromine:
1s*2 2s*2 2p*6 3s*2 3p*6 4s*2 3d*10 4p*5 How many valance electrons does bromine have? |
Since bromine has two electrons in the 4s orbital and five electrons in the 4p orbitals, it has seven valence electrons. Those seven electrons are responsible for almost all of bromine's chemical behavior.
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An atom's chemistry is mostly determined by _____________________________________________________ (finish the sentence with the appropriate words)
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MEMORIZE: An atom's chemistry is mostly determined by the number of valence electrons it has.
(very important point to remember!!) |
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The periodic table is arranged so as to guarantee that all atoms in a given column have what in common? (means they have essentially the same chemistry)
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Atoms in the same column of the periodic chart have the same number of valence electrons and thus have very similar chemistry.
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Since the columns of the periodic chart contain atoms of similar chemistry, they are often called __________ or ____________.
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groups or families
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What does "ideal electron configurations in nature" mean in terms of atoms?
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It means that the s and p orbitals in their highest energy level are full. It turns out that this is a very low-energy situation, and, since all matter strives to get to the lowest energy possible, we consider such an electron configuration to be ideal.
It also means: The electron configuration of an atom determines its chemistry. Since these atoms already have ideal electron configurations, there is no need for them to change, so they will almost never undergo a chemical change. |
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The noble gases regularly participate in chemical reactions. True or false?
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False! The noble gases rarely participate in chemical reactions. (inert substance!)
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What are chemical reactions really striving to attain?
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Chemical reactions are really just the result of atoms trying to rearrange their electrons so that they can get an ideal electron configuration.
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There is one exception to the octet rule that we need to remember. What is it?
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All atoms except for hydrogen strive for eight valence electrons. Hydrogen strives for two.
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For atoms in groups 1A-8A, what does the number of the column in which the atom is located on the periodic chart equal?
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the number of valence electrons the atom has.
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The Lewis structure has dots that represent the number of valence electrons that the atom has. What is another way to tell how many valence electrons an atom has?
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the atom's column number on the periodic chart
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True or False? The dots in a Lewis structure also represent the total number of electrons that the atom has.
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False!!!
The dots do NOT represent the total number of electrons that the atom has. That number is given by the atomic number on the chart. The dots represent the number of valence electrons that the atom has, which is given by the column number on the chart. |
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Describe the dots in an ideal Lewis structure configuration.
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It has a pair of dots on each side and at the top and bottom of the elemental symbol. (eight)
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Draw the Lewis structures for the following atom:
Ca |
Since Ca is in group 2A, it has two valence electrons:
C* * (Obviously...Lewis structures are hard to do in flashcard form. Bear with me!) :o) |
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Draw the Lewis structures for the following atom:
Si |
Since Si is in group 4A, it has four valence electrons:
* * Si * * |
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Draw the Lewis structures for the following atom:
At |
Since At is in group 7A, it has seven valence electrons:
. : At : . . (sorry... best I could do) |
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On the periodic chart, how are metals and nonmetals distinguished from each other?
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On the periodic chart, there is a heavy jagged line that runs down the right side of the table. All elements to the left of the line are metals (except hydrogen), and all elements to the right of the line (plus hydrogen) are nonmetals.
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There are two main points to remember in terms of Lewis structures, metals, nonmetals, and electrons. What are they?
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1. In ionic compounds, nonmetals try to gain electrons so that their Lewis structure has eight dots around it. (Hydrogen, of course, is an exception to this rule. When hydrogen is a part of an ionic compound, it gains an electron to get two dots in its Lewis structure, not eight.)
2. In ionic compounds, metals try to lose electrons until their Lewis structure has no dots around it. |
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What does it mean when a metal's Lewis structure has no dots?
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When a metal's Lewis structure has no dots, it has the ideal electron configuration and will be stable. This is, in fact, the fundamental difference between metals and nonmetals: nonmetals try to gain electrons, while metals try to lose electrons.
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What desire governs the formation of all molecules?
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Atoms will join together in such a way as to make sure that they all end up with ideal electron configurations.
(they desire to be ideal electron configurations...) |
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When a sodium atom loses an electron, it is no longer a sodium atom. True or false?
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True. When an atom gives up or gains one or more electrons to become electrically charged, we no longer refer to it as an atom. We call it an ion.
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when a sodium atom loses an electron, it is no longer a sodium atom. Why not?
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Remember, all atoms have the same number of protons and electrons. A sodium atom, according to the periodic chart, has 11 protons and thus 11 electrons. But when sodium gives up an electron, it ends up with 11 protons and only 10 electrons.
Thus, it has more positive charges (protons) than negative charges (electrons). This gives it an overall positive charge. Since it has one more proton than it has electrons, we say it has a 1+ charge. |
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Chemists love to drop 1's. They do not report 1's in chemical formulas or chemical equations. In the same way, they often do not report 1's with electrical charges. So instead of listing the charge as “1+”, how do you list it?
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simply by using the "+" symbol
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Positively charged ions keep the same name as the atom from which they came. Negative ions, on the other hand are dealt with differently. How so?
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Positive ions have the same name as the atom from which they came.
Negative ions have an “ide” suffix added to the name of the atom from which they came. |
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Since table salt is made up of a sodium ion and a chloride ion, what is the name of the ionic compound?
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sodium chloride
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Electrons are negative. When atoms gain an electron, what charge does it develope? How about when an atom loses and electron?
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Remember, electrons are negative, so the atoms that gain electrons (nonmetals) will develop negative charges and the atoms that lose electrons (metals) will develop positive charges.
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How do ionic compounds get their chemical formulas?
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The atoms start exchanging electrons until all of them attain an ideal electron configuration. Once they all have achieved this, they are attracted to one another because of the electrical charges that they have gained. This electrical attraction is what holds ionic compounds together.
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What are the two rules to follow (after you've determined the charge) if you want to determine the chemical formula?
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1. If the charges have the same numerical value, then the subscript for each ion is “1” and can therefore be ignored.
2. If the charges have different numerical values, drop the + and - signs, switch the numbers, and use them as subscripts. |
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Give the chemical formula for the following compound:
calcium chloride |
Since calcium is in group 2A, it has a 2+ charge. Chlorine is in group 7A, so chloride has a 1- charge. Ignoring the + and - signs and switching the numbers gives us:
CaCl^2 |
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Give the chemical formula for the following compound:
potassium sulfide |
Since potassium is in group 1A, it has a 1+ charge. Sulfur is in group 6A, so sulfide has a 2- charge. Ignoring the + and - signs and switching the numbers gives us:
K^2S |
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Give the chemical formula for the following compound:
aluminum nitride |
Since aluminum is in group 3A, it has a 3+ charge. Nitrogen is in group 5A, so nitride has a 3- charge. The numerical values of the charge are identical, so we ignore them:
AlN |
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Give the chemical formula for the following compound:
magnesium phosphide |
Since magnesium is in group 2A, it has a 2+ charge. Phosphorus is in group 5A, so phosphide has a 3- charge. Ignoring the + and - signs and switching the numbers gives us:
Mg^3P^2 |
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When a Roman numeral is inserted in the name of a compound and put in parentheses, what does it indicate?
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This Roman numeral represents the positive charge of the metal.
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tin(II) chloride
What two things does this name tell us? |
1. First, it tells us that the metal we are dealing with is an exception to the rules. We know this because of the Roman numeral in the name.
2. Second, it tells us that in this particular compound, tin has a charge of 2+. Chlorine is not an exception, so chloride has a charge of 1-. |
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What would the formula for tin(II) chloride be?
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SnCl^2
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True or false? Tin can have two charges...
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True. 2+ is not the only charge that tin can have. Because of reasons too complex to explain here, tin also can have a charge of 4+
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If tin has a charge of 4+, then what would the name and the formula be then?
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tin(IV) chloride
SnCl^4 |
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Give the chemical formula of the following compound:
iron(III) fluoride |
In this problem, the Roman numeral after iron tells you that it has a 3+ charge. Fluorine is in group 7A, and thus fluoride has a 1- charge. Ignoring the signs and switching the numbers gives us FeF^3.
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Give the chemical formula of the following compound:
copper(I) iodide |
In this problem, the Roman numeral after copper tells you that it has a 1+ charge. Iodine is in group 7A, and thus iodide has a 1- charge. The numerical values of the charges are the same, so we ignore them, giving us CuI.
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Give the chemical formula of the following compound:
manganese(III) oxide |
In this problem, the Roman numeral after manganese tells you that it has a 3+ charge. Oxygen is in group 6A, and therefore oxide has a 2- charge. Ignoring the signs and switching the numbers gives us Mn^2O^3.
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It turns out that each atom holds onto its valence electrons with a different strength. Some hold them tightly, while others hold them rather loosely. What does this mean in terms of energy?
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For those atoms that hold their valence electrons tightly, it takes a lot of energy to take an electron away. On the other hand, if an atom holds on to its valence electrons loosely, not much energy is required in order to remove one.
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How do we know whether or not an atom holds on to its electrons tightly or loosely?
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It depends on the atom's electron configuration and can be determined from the periodic chart.
Thus, one thing we can say is that as you look at the periodic chart, the elements on the left side of the chart have a rather low ionization potential (they give up their electrons easily), while the atoms on the right side of the periodic chart have high ionization potentials (they give up their electrons grudgingly). In general, the ionization potential of atoms increases from the left of the periodic chart to the right of the periodic chart. |
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Mg lies left of P on the periodic chart. Which one has the lower ionization potential?
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Mg has a lower ionization potential than P.
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Not only does ionization potential change from left to right on the periodic chart, it also changes from the top to the bottom. True? Or False?
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True. It turns out that atoms near the top of the periodic chart hold on to their electrons more tightly than those on the bottom on the chart, so the ionization potential of atoms decreases from the top of the periodic chart to the bottom of the periodic chart.
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O and Se are both in the same column of the chart, so neither lies to the left or right of the other. Which one has the higher ionization potential?
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Since O is above Se on the periodic chart, O has a higher ionization potential than Se.
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Order the following atoms in terms of increasing ionization potential: I, Ru, Sn, Rb.
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These elements all lie in the same row. This means that the only difference in their position on the chart is left to right. Based on the fact that ionization potential increases from left to right on the chart, the correct order is:
Rb < Ru < Sn < I |
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Which atom most readily gives up its electrons: K, Li, Cs, or Fr?
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The only difference in position for these elements is vertical. Based on the fact that ionization potential decreases from top to bottom on the chart, Fr has the lowest ionization potential. This means that Fr gives up its electrons most readily.
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Is there a way of determining how much an atom desires to gain electrons?
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Yes, through electronegativity.
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As the electronegativity of an atom increases, its desire to become a negative ion increases.
True? Or False? |
True.
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Which element desires electrons most: Mg, P, Na, or S?
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All of these atoms are in the same row on the periodic chart, so the only difference between their positions is left to right. Since S lies farthest to the right, it has the highest electronegativity. This means that S has the highest desire for electrons.
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Order the following in terms of increasing desire for electrons: F, At, Cl, I, and Br.
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These elements all lie in the same column on the chart, so their only difference in position is top to bottom. Based on the fact that electronegativity decreases from top to bottom of the chart, the order is:
At < I < Br < Cl < F |
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Atoms that are lower on the periodic chart tend to have their valence electrons closer to the nucleus as compared to atoms that appear near the top of the chart. True or False?
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False. Atoms that are higher on the periodic chart tend to have their valence electrons closer to the nucleus as compared to atoms that appear near the bottom of the chart.
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1. In general, the atomic radius increases from top to bottom on the periodic chart.
2. In general, the atomic radius increases from left to right on the periodic chart. Which one of these two statements is false? |
The second one.
It should be: In general, the atomic radius decreases from left to right on the periodic chart. |
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as you travel from left to right on the periodic chart, the atomic number of the atom is increasing. What does that tell you?
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It tells you that the number of protons in an atom increases as you travel across the chart. Thus, the total positive charge in the nucleus increases. What does that mean? It means that the nucleus can exert more electrical force on the electrons, pulling them closer . As a result, when you travel from left to right on the periodic chart, the size of the atoms actually decreases !
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Which element is the largest: Mg, P, Na, or S?
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All of these elements are in the same row. Since the atomic radius decreases from left to right on the periodic chart, the leftmost element will be largest. That means Na is the largest.
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Order the following in terms of increasing atomic radius: F, At, Cl, I, and Br.
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All of these elements are in the same column. Since the atomic radius increases as you move down the chart, the order is:
F < Cl < Br < I < At |
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How do covalent compounds and ionic compounds differ in how they deal with electrons?
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The atoms in covalent compounds SHARE electrons in order to form molecules, while the atoms in ionic compounds GIVE AND TAKE electrons to form ions.
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Why do the atoms in ionic molecules stay together?
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The atoms in ionic molecules stay together because of the fact that the positively charged ions are attracted to the negatively charged ions.
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In covalent compounds, what holds the atoms together?
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In covalent compounds, however, there is a physical bond (a pair of shared electrons) which holds the atoms together.
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Covalent compounds contain only nonmetals. Nonmetals always gain electrons. They never give up electrons.
Thus, how do nonmetals combine together to get ideal electron configurations if none of them are willing to give up electrons so that others can gain them? |
If two nonmetals come together and neither will give up its electrons, the two atoms will share electrons in order to help them both attain ideal electron configurations.
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The elements H, N, O, F, Cl, Br, I, and At have something in common. What is it?
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They all exist as homonuclear diatomics. (F^2 for example)
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In order to determine what a molecule of any covalent compound looks like, what do you have to do?
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Like a jigsaw puzzle, all you have to do is find out how you can “fit” the atoms together in such a way as to give every atom its ideal electron configuration.
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If you see a dash in a Lewis structure, what does it mean?
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It indicates a covalent bond. Since the covalent bond created by shared electron pairs is the thing that holds the atoms in a molecule together, we often emphasize this in the Lewis structure by replacing the pair of dots with a dash. This illustrates that there is something physically attaching one atom to the other. It also helps to distinguish the electron pairs that are not being shared from the ones that are being shared.
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When putting together a jigsaw puzzle, experts will tell you to construct the frame of the puzzle first. Since the frame pieces are generally the easiest to find, it tends to make things go more quickly if you start there. In putting together Lewis structures you follow the same method. True or False?
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False!! In putting together Lewis structures, however, it is best to start at the center and work your way out. Generally, you take the atom with the most unpaired electrons and put it in the center. You then try to attach the remaining atoms to this one central atom. If you happen to have more than one of the atom with the most unpaired electrons, you generally hook them all together and put the whole chain in the center.
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In summary, determining the Lewis structure for a molecule is rather like putting together a puzzle, as long as we follow three general guidelines. What are they?
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1. Write out the Lewis structures for all atoms in the chemical formula. This gives you an idea of what you have to work with. You must work with the number of dots in those Lewis structures: no more, no less.
2. Put the atom with most unpaired electrons in the center. If there is more than one of those atoms, put them all in the center, linked together. 3. Try to arrange the other atoms around the atom(s) you put in the center, making sure that they all end up with eight dots around them, except for H atoms, which should only have two dots. |
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Because molecules are free to rotate in three-dimensional space, you can have more than one Lewis structure possible!! True or False?
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True.
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A dot counts for an atom in a Lewis structure if it is next to the atom's symbol or in between the atom's symbol and another atom's symbol. Is this true or false?
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True! (and very important to remember....)
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In a Lewis structure, you replace each shared electron pair with a dash to indicate that it is a covalent bond. What do you do if there are two shared electron pairs?
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Since there are two shared electron pairs you must use two dashes..... one for each shared pair.
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How does nitrogen protect the earth from harmful gamma rays?
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The highest-energy light that comes from the sun consists of gamma rays. These light waves have very small wavelengths, indicating very large energy. As these light waves strike our atmosphere, they encounter an enormous amount of nitrogen.
Nitrogen's triple bond makes the nitrogen molecule very hard to break apart. These high-energy light rays, however, have plenty of energy, so when they strike the nitrogen molecule, they are able to break it apart. This, however, uses up all of the energy in the light wave. As I said in Module #1, light is pure energy. Thus, when the energy gets used up, the light wave is gone! |
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X-rays strike the earth's atmosphere daily. Although these light waves still have enough energy to destroy living tissue, they do not have enough energy to break apart nitrogen molecules. Thus, the nitrogen cannot block them.
What in our atmosphere DOES block the x-rays? |
Oxygen in the atmosphere blocks it. The double bond indicates that the oxygen molecule is held together tightly, but not as tightly as the nitrogen molecule. Although X-rays cannot break nitrogen molecules apart, they can break oxygen molecules apart. Thus, the oxygen in our atmosphere blocks the X-rays that come from the sun.
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Ultraviolet rays have enough energy to destroy living tissue, but not enough energy to break apart oxygen molecules. Thus, oxygen cannot block ultraviolet rays.
What does block ultraviolet rays? |
Ozone. Ozone is uniquely designed to block ultraviolet light that comes from the sun. Ultraviolet light has less energy than gamma rays, so it cannot break apart a molecule with a double bond. However, ozone has a single bond, which is weaker than a double bond. Ultraviolet light has just enough energy to break this bond. Once again, when the bond is broken, the energy of the light is used up, so the light disappears.
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Describe the three-tiered protection system to protect us from high-energy light.
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The nitrogen in the atmosphere protects us from the most highly energetic light; the oxygen in the atmosphere protects us from the intermediately high-energy light; and the ozone in the atmosphere protects us from the moderately high-energy light.
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What are valence electrons and why are they so important in chemistry?
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Valence electrons are those electrons farthest away from the nucleus of an atom. They are important in chemistry because they are responsible for determining the chemical behavior of an atom.
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How many valence electrons are in the following electron configuration?
1s*2 2s*2 2p*6 3s*2 3p*6 4s*2 3d*10 4p*6 5s*2 4d*10 5p*3 |
The valence electrons in this configuration are the ones in the fifth energy level, since this is the
farthest from the nucleus. There are a total of 5 (3 + 2) electrons in the fifth energy level, so there are 5 valence electrons. |
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The chemistry of life is based on carbon. This means that all of the molecules which govern life-giving chemistry have carbon atoms as their principal component. Chemists have often speculated that there could be a life form with a chemistry based on silicon. Why?
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Since life is based on carbon, it could, in theory, be based on any atom in the same column, since
they all have similar chemistry. Thus, life could be based on Si, Ge, Sn, or Pb as well. |
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What are the noble gases and why are they important in chemistry?
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The noble gases are the elements in group 8A. They are important because they have ideal electron
configurations. |
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What is the fundamental difference between metals and nonmetals?
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Metals tend to give up electrons to attain the ideal electron configuration, while nonmetals tend to gain electrons for the same purpose.
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What is the difference between an atom and an ion?
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An atom has no electrical charge. Ions have electrical charge because they have an imbalance of
protons and electrons. |
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What is ionization potential?
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Ionization potential is the energy required to remove an electron from an atom.
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Name three periodic properties of atoms.
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Ionization potential, electronegativity, and atomic radius are all periodic properties.
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What is the fundamental difference between ionic compounds and covalent compounds?
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Ionic compounds form when atoms give and take electrons. Thus, they are composed of ions.
Covalent compounds result when atoms share electrons. Thus, no ions are formed. |
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What gases are involved in earth's three-tiered protection system against high-energy light that comes from the sun?
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Nitrogen, oxygen, and ozone protect the earth from the harmful rays of the sun.
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Give the chemical formula for the following molecule:
aluminum sulfide |
Al is in group 3A, so it wants a charge of 3+. Sulfur is in group 6A, so sulfide will have a charge of 2-. Ignoring the signs and switching the numbers gives us Al^2S^3.
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Give the chemical formula for the following molecule:
cesium nitride |
Cs is in group 1A, so it wants a charge of 1+. Nitrogen is in group 5A, so nitride will have a charge of 3-. Ignoring the signs and switching the numbers gives us Cs^3N.
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Give the chemical formula for the following molecule:
magnesium oxide |
Mg is in group 2A, so it wants a charge of 2+. Oxygen is in group 6A, so oxide will have a charge of 2-. The numbers are the same so we ignore them: MgO.
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Give the chemical formula for the following molecule:
chromium(III) oxide |
Cr is an exception, because there is a Roman numeral in the name. The numeral tells us that Cr wants a charge of 3+. Oxygen is in group 6A, so oxide will have a charge of 2-. Ignoring the signs and
switching the numbers gives us Cr^2O^3. |
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Which atom gives up its electrons most readily: Al, B, In, or Ga?
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Ionization potential decreases as you go down the chart. The atom with the lowest ionization
potential will give up its electrons easiest. That would be In. |
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Order the following atoms in terms of increasing ionization potential: Sr, Sb, I.
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Ionization potential increases as you go from left to right on the chart, so the order is Sr < Sb < I.
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Which atom has the greatest desire for extra electrons: N, Sb, or As?
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Electronegativity decreases as you go down the chart, so N has the greatest desire for extra electrons.
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Order the following in terms of increasing atomic radius: As, K, Br, Se.
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Atomic radius decreases as you go from left to right on the chart, so the order is Br < Se < As < K.
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