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Ch.7 - Periodic Properties of the Elements

Chapter 7, Problem 106

A historian discovers a nineteenth-century notebook in which some observations, dated 1822, were recorded on a substance thought to be a new element. Here are some of the data recorded in the notebook: 'Ductile, silver-white, metallic looking. Softer than lead. Unaffected by water. Stable in air. Melting point: 153 °C. Density: 7.3 g>cm3. Electrical conductivity: 20% that of copper. Hardness: About 1% as hard as iron. When 4.20 g of the unknown is heated in an excess of oxygen, 5.08 g of a white solid is formed. The solid could be sublimed by heating to over 800 °C.' (a) Using information in the text and the CRC Handbook of Chemistry and Physics, and making allowances for possible variations in numbers from current values, identify the element reported.

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Hey everyone in this example, we need to determine the identity of the unknown solid Melanie Lloyd that is observed to have the following properties. So we're given the property that it's a semi conductor of electricity. We have the following boiling point, which is a very high boiling 0.0.3538 kelvin. We have a very high melting point as well, 1687 kelvin. And then we have a density value of 2.32296 g per millimeter, which is a greater value than the density of water, which we recall. Sorry, there should be a pen Is equal to 1.0 g per mil leader. So it has a greater density of water. So because they tell us in this question that our compound should be a metal Lloyd, we want to recall the metal Lloyd's on our periodic table. So we would consider the metal Lloyd's of our periodic table to be distinguished by either boron, silicon, arsenic, delirium, antimony, germanium. And these are our six metal Lloyd's that we can find on our periodic table. So we want to go ahead and refer to our textbooks as well as our online google searches to find whether these properties correspond to any of the given metal Lloyd's on the right and when we look these properties up, we will see that we have a match to these properties corresponding to our atom silicon here. So when we look up silicon, we would see that it has the boiling point of around this value here, The melting point around this value given, and the density of 2.3296 g per milliliter. And because it's a meta Lloyd, we would recall that metal Lloyd's are semi conductors of electricity. And so because we do have this match of properties with this adam silicon, we would say that this is the identity of the unknown solid metal Lloyd. So this will complete this example as our final answer where S eye represents silicon. So if you have any questions, please leave them down below. Otherwise, I will see everyone in the next practice video.
Related Practice
Textbook Question

The first ionization energy of the oxygen molecule is the energy required for the following process: O21g2¡O2 +1g2 + e- The energy needed for this process is 1175 kJ>mol, very similar to the first ionization energy of Xe. Would you expect O2 to react with F2? If so, suggest a product or products of this reaction.

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Textbook Question

It is possible to define metallic character as we do in this book and base it on the reactivity of the element and the ease with which it loses electrons. Alternatively, one could measure how well electricity is conducted by each of the elements to determine how 'metallic' the elements are. On the basis of conductivity, there is not much of a trend in the periodic table: Silver is the most conductive metal, and manganese the least. Look up the first ionization energies of silver and manganese; which of these two elements would you call more metallic based on the way we define it in this book?

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Textbook Question

Which of the following is the expected product of the reaction of K(s) and H2(g)? (i) KH(s), (ii) K2H(s), (iii) KH2(s), (iv) K2H2(s), or (v) K(s) and H2(g) will not react with one another.

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Textbook Question

We will see in Chapter 12 that semiconductors are materials that conduct electricity better than nonmetals but not as well as metals. The only two elements in the periodic table that are technologically useful semiconductors are silicon and germanium. Integrated circuits in computer chips today are based on silicon. Compound semiconductors are also used in the electronics industry. Examples are gallium arsenide, GaAs; gallium phosphide, GaP; cadmium sulfide, CdS; and cadmium selenide, CdSe. (a) What is the relationship between the compound semiconductors' compositions and the positions of their elements on the periodic table relative to Si and Ge?

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Textbook Question

We will see in Chapter 12 that semiconductors are materials that conduct electricity better than nonmetals but not as well as metals. The only two elements in the periodic table that are technologically useful semiconductors are silicon and germanium. Integrated circuits in computer chips today are based on silicon. Compound semiconductors are also used in the electronics industry. Examples are gallium arsenide, GaAs; gallium phosphide, GaP; cadmium sulfide, CdS; and cadmium selenide, CdSe. (b) Workers in the semiconductor industry refer to 'II–VI' and 'III–V' materials, using Roman numerals. Can you identify which compound semiconductors are II–VI and which are III–V?

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Textbook Question

Moseley established the concept of atomic number by studying X rays emitted by the elements. The X rays emitted by some of the elements have the following wavelengths: Element Wavelength (pm) Ne 1461 Ca 335.8 Zn 143.5 Zr 78.6 Sn 49.1 (a) Calculate the frequency, n, of the X rays emitted by each of the elements, in Hz.

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