Why These Elements

There are usually between 60 and 80 critical safety activities (elements) that mnst be controlled to constitnte an effective safety system. These elements may vary from organization to organization and from industry to industry. The emphasis on individual elements will also vary according to the nature of the process, culture of the workforce, and category of business, such as mining, the iron and steel industry, transportation, the fishing industry, manufacturing, etc. 

Experience has shown that there are between 60 and 80 critical safety arenas (elements) that must be controlled constantly to constitute an effective safety program. Many are dictated by local and national safety laws and legislation and are compulsory anyway. These legal requirements should be viewed as the minimum standard and management should extend the safety program to best practice rather than only complying to the minimum legal requirements. 

The benefit of controlling critical safety elements is that the work being done to manage safety is channeled at reducing the risk and potential loss in areas that have been identified as crucial. Some critical safety elements help control the physical conditions that would contribute to the reduction of losses as a result of an unsafe work environment. Other critical safety elements are directed toward the control of the persons within a workplace. These controls would include items such as critical task procedures, rules, training, and activities to involve, motivate, guide, and train employees in safe work practices. 

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Nickel catalysts used in steam reforming are more resistant to deactivation by carbon deposition if the surface contains sulfur, or gold. Explain why these elements act as promoters. Would you prefer sulfur or gold as a promoter Explain your answer. 

Down any group (vertical column), the properties of elements tend to be remarkably similar, which is why these elements are said to be grouped or in a family. As Figure 2.28 shows, several groups have traditional names that... 

We now discuss just why these elements out of the entire periodic table have been selected. One thing is clear — they were not only selected as a function of their abundance and their availability in the universe as well as in the earth s crust, and the oceans (which constitute the major proportion of the earth s surface), but also on the basis of their suitability for the functions that they are called upon to play, in what is predominantly an aqueous environment." ... 

In the case of animals, the absence or very low level of an essential element may lead to poor development, sickness and, in case of total absence, to death. For example, if the diet of a chicken is deficient in manganese, its eggs do not hatch, and manganese deficiency is also said to lead to sterility. This is the reason why these elements are deliberately added in feed formulations. ... 

Draw electron-dot symbols for the nonmetallic elements and use them to explain why these elements form the bonding patterns listed in Table 3.1. 

The mass in grams of one mole of substance is called molar mass. Each element has its own unique molar mass. For example, carbon s molar mass is 12.011 g/mol, and magnesium s molar mass is 24.3050 g/mol. To see why these elements have different molar masses, we need to remember that the atoms of different elements contain different numbers of protons, neutrons, and electrons, so they have different masses. The atomic masses given in the periodic table represent the different weighted average masses of the naturally occurring atoms of each element. 

Half of the first 18 elements have an odd number of electrons, and half have an even number. Show why these elements aren t half paramagnetic and half diamagnetic. 

Recycling of rare earths is until recently rarely undertaken in practice (Binnemans and Jones 2014 Graedel et al. 2011). Marshall (2014) points out several reasons why. These elements are present in only very small amounts in things like cell phones, and, as parts get smaller, so do the amounts of material used. In a touch screen, the elements are distributed throughout the material at the molecular level, and thus are not present as separate parts. 

Look at the table of electron configurations in Appendix C. Which elements have configurations that are exceptions to the aufbau principle Propose a reason why these elements have these exceptions. 

Although the simplest identifiable units of an element are its corresponding atoms, a number of elements exist in nature as diatomic molecules-two atoms bonded together-as shown in Figure 3-18. These elements are hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine. In Chapter 5, we will learn a theory that explains why these elements form diatomic molecules. 

Iron, cobalt, and nickel are similar in properties and are sometimes studied together as the iron triad. For example, each is a fairly active metal that reacts with acids to give hydrogen and the -1-2 ions. In addition to the -1-2 ions, the -1-3 ions of the metals also figure prominently in the chemistries of the elements. Explain why these elements are similar. 

These halides are all of the general formula MX2, a fact that demonstrates once again the degree to which the +2 oxidation state dominates the chemistry of these elements. (See Chapter 8 for an extended thermochemical discussion of why these elements do not form either MX or MX3 salts.)... 

The large dip in the PDOS of Mo and other transition metals with half-filled d bands is actually the reason why these elements possess a bcc structure. Systems typically prefer an atomic structure that leads to... 

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