Atomic inside covers

The possibility that an even larger impact caused the P T extinction received support when Becker and Poreda found that helium and argon atoms were present in the inner cores of some of the fullerenes from the P T boundary sediments (The cover of this book shows a helium atom inside a mol ecule of Ceo) What is special about the fullerene trapped atoms is that the mixtures of both helium and argon isotopes resemble extraterrestrial isotopic mixtures more than earthly ones The He/ He ratio in the P T boundary fullerenes for example is 50 times larger than the natural abundance ratio... 

Obviously, one requirement for an adhesive is that it flow easily to cover a surface. This is a more complex business than it first appears. One might naively think that the governing feature is whether we are dealing with a thin or a thick liquid, but this is not the case. If we put a drop of oil in an iron skillet, it spreads, but on a Teflon surface it beads up. The explanation revolves around surface energies, which are a measure of the relative strengths with which atoms on the surface of a material are attracted to atoms inside the bulk of the material. In a sense, this determines how much attraction these surface atoms can spare for other substances. In the case of Teflon, very little. Teflon is composed of long chains of carbon atoms, with each carbon also joined to two fluorine atoms. The fluorines, which stick out from the carbon skeleton, represent the exposed part of the molecules, the part that could potentially interact with other molecules. Fluorine, once it has bonded to carbon, is notoriously unreactive, and it is not interested in forging other... 

What is the uncertainty in the molecular mass of 02 On the inside cover of this book, we find that the atomic mass of oxygen is 15.9994 0.000 3g/mol. The uncertainty is not mainly from random error in measuring the atomic mass. The uncertainty is predominantly from isotopic variation in samples of oxygen from different sources. That is, oxygen from one source could have a mean atomic mass of 15.999 1 and oxygen from another source could have an atomic mass of 15.999 7. The atomic mass of oxygen in a particular lot of reagent has a systematic uncertainty. It could be relatively constant at 15.999 7 or 15.999 1, or any value in between, with only a small random variation around the mean value. 

The inside cover of this book lists the atomic number (the integer mass) of the long-lived isotope of Ra, which is 226. 

Another way to determine atomic mass is to check a periodic table, such as the one on the inside cover of this book. The mass shown is an average of the atomic masses of the naturally occurring isotopes. For this reason, copper is listed as 63.546 instead of 62.940 or 64.928. 

Atomic weights and atomic numbers of the elements, listed alphabetically, are given on the front inside cover of this text. The values are a composite of the best agreements among the tables in the websites listed below. Additional information about each element can be found jBrom various versions of the periodic. table. There are many available on the Web. Following are some recommended ones. In most, you can click on an element and obtain atomic weight and number and other properties such as isotopes, physical properties, and history of the element. 

No," Bajan said. "You can t jump with sensors extended, the distortion effect collapses any mass caught in the field. Fortunately it s only a very narrow shell which covers the hull, just a few micrometers thick. But the atoms inside it get converted directly into energy. Most of it shoots outwards, but there s also some which is deflected right back against the hull. That s what hit us."... 

For each of the following elements, use the periodic table on the inside cover of this book to write the element s atomic number, symbol, or name. 

Consider the three isotopes of magnesium discussed in Exercise 17. Given that the relative natural abundances of these isotopes are 79%, 10%, and 11%, respectively, without looking at the inside cover of this book, what is the approximate atomic molar mass of magnesium Explain how you made your prediction. 

The names and formulas of the common anions are listed in TABLE 2.5 and on the back inside cover of the text. Those anions whose names end in -ide are listed on the left portion of Table 2.5, and those whose names end in -ate are listed on the right. The most common of these ions are shown in boldface. You should learn names and formulas of these anions first. The formulas of the ions whose names end with -ite can be derived from those ending in -ate by removing an O atom. Notice the location of the monatomic ions in the periodic table. Those of group 7A always have a 1— charge (F , Cl, Br , and I ), and those of group 6A have a 2— charge (0 and ). 

Following the complete filling of the 4s orbital (this occurs in the calcium atom), the next set of orbitals to be filled is the 3d. (You will find it helpful as we go along to refer often to the periodic table on the front inside cover.) Beginning with scandium and extending through zinc, electrons are added to the five 3d orbitals until they are completely filled. Thus, the fourth row of the periodic table is ten elements wider than the two previous rows. These ten elements are known as either transition elements or transition metals. Note the position of these elements in the periodic table. 

Once all the 3d orbitals have been filled with two electrons each, the 4p orbitals begin to be occupied until the completed octet of outer electrons (4s 4p ) is reached with krypton (Kr), atomic number 36, another of the noble gases. Rubidium (Rb) marks the beginning of the fifth row. Refer again to the periodic table on the front inside cover. Notice that this row is in every respect like the preceding one, except that the value for K is greater by 1. 

Calculate the uncertainty in the position of (a) an electron moving at a speed of (3.00 0.01) X 10 m/s, (b) a neutron moving at this same speed. (The masses of an electron and a neutron are given in the table of fundamental constants in the inside cover of the text) (c) What are the imphcations of these calculations to our model of the atom ... 

Solve A 27C0 atom has 27 electrons. The mass of an electron is 5.4858 X 10 amu. (See the list of fundamental constants in the back inside cover.) We subtract the mass of the 27 electrons from the mass of the 27C0 atom to find the mass of the 27C0 nucleus ... 

What makes an atom of one element different from an atom of another element The atoms of each element have a characteristic number of protons. The munber of protons in an atom of any particular element is called that element s atomic number. Because an atom has no net electrical charge, the munber of electrons it contains must equal the number of protons. All atoms of carbon, for exeunple, have six protons and six electrons, whereas all atoms of oxygen have eight protons and eight electrons. Thus, Ccffbon heis atomic number 6, and oxygen heis atomic munber 8. The atomic munber of each element is listed with the name and symbol of the element on the front inside cover of the text. 

The atomic weights of the elements are Hsted in both the periodic table and the table of elements front inside cover of this text. 

The two most common isotopes of uranium are U and U. (a) Compare the number of protons, the number of electrons, and the number of neutrons in atoms of these two isotopes, (b) Using the periodic table in the front-inside cover, write the electron configuration for a U atom. 

Looking at the periodic table on the front inside cover, can you find an example other than Ar and K where the order of the elements would be different if the elements were arranged in order of increasing atomic weight ... 

Atoms of a given element that differ in the number of neutrons, and consequently in mass, are called isotopes. The symbol C or simply (read "carbon twelve," carbon-12) represents the carbon atom with six protons and six neutrons. The number of protons, which is called the atomic number, is shown by Ihe subscript. The atomic number of each element is listed witii the name and symbol of Ihe element on the front inside cover of tire text. Because all atoms of a given element have the same atomic number, tire subscript is redundant and hence is usually omitted. The superscript is called tire mass number it is Ihe total number of protons plus neutrons in the atom. Some carbon atoms, for example, contain six protons and eight neutrons and are consequently represented as (read "carbon fourteen"). Several isotopes of carbon are listed in Table 2.2 T. 

Solution The superscript 197 is the mass number, the sum of the numbers of protons and neutrons. According to the list of elements given on the front inside cover of this text, gold has an atomic number of 79. Consequently, an atom of Au has 79 protons, 79 electrons, and 197 — 79 = 118 neutrons. 

---