Properties of s-Block Elements

Because elements in a given group have the same number of valence electrons, they have similar properties. The properties are not identical, however, because the numbers of nonvalence electrons differ. For example, the ionization energy of elements in a group decreases as the atomic number increases. For that reason, metals, which tend to lose electrons when they react, increase in reactivity as the atomic number increases. Nonmetals, which tend to gain electrons, decrease in reactivity as the atomic number increases. 

Sometimes a period-2 element has more properties in common with a period-3 element in a neighboring group than with the period-3 element in its own group. Such a relationship is called a diagonal relationship. 

1 -I- ions. Lithium, the least reactive alkali metal, has a diagonal relationship with magnesium, a group 2A metal. Sodium and potassium are the most abundant alkali metals. The most common sodium 

Describe the following pair of elements in terms of group number, number of valence electrons, typical ion formed, ionization energy, and reactivity. 

Both sodium and potassium are in group lA. They each have one valence electron and form 1 + ions. Sodium is above potassium in the group thus, sodium has a higher ionization energy and is less reactive than potassium. 

If you could travel through the universe to collect samples of matter, you would find 92 naturally occurring elements. The amount of each element would vary from location to location. Helium, which is the second most common element in the universe, is much less abundant here on Earth. Oxygen is the most abundant element on Earth. Per kilogram of Earth s crust, there are 4.64 x 10 mg of oxygen, but only 8 X 10 mg of helium. Elements with atomic numbers greater than 92 do not exist in nature. These synthetic elements must be created in laboratories or nuclear reactors. 

Elements in any given group on the periodic table have the same number of valence electrons. The number and location of valence electrons determine the chemistry of an element. Thus, elements within a group have similar physical and chemical properties. Representative elements display the range of possible valence electrons from one in group lAto eight in group 8A. The valence electrons of representative elements are in s or p orbitals. 

The diagonal arrows connect pairs of elements that have similar properties. 

Why are the properties of elements within a group similar hut not identical Although elements within a group have the same number of valence electrons, they have different numbers of nonvalence electrons. Remember what happens as the atomic number increases within a group. As new levels of electrons are added, the atomic radius increases and the shielding effect increases. As a result, the ionization energy decreases. A lower ionization energy makes it easier for an element to lose electrons. 

Recall that metals tend to lose electrons. Thus, the lower the ionization energy, the more reactive the metal. For a group of metals, reachvity increases as the atomic number increases. The opposite is true for nonmetals because nonmetals tend to gain electrons. The higher the ionization energy of a non-metal, the more reactive the nonmetal. For a group of nonmetals, reactivity decreases as the atomic number increases. Of the representative elements, which is the most reactive metal Which is the most reactive nonmetal (Hint What is the trend for ionization energy across a period ) 

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S.F.A. Kettle (1996) Physical Inorganic Chemistry, Spektrum, Oxford - Chapter 11 gives an excellent introduction to orbital, spectroscopic and magnetic properties of the /-block elements. 

The usefulness of the main-group elements in materials is related to their properties, which can be predicted from periodic trends. For example, an s-block element has a low ionization energy, which means that its outermost electrons can easily be lost. An s-block element is therefore likely to be a reactive metal with all the characteristics that the name metal implies (Table 1.4, Fig. 1.60). Because ionization energies are... 

All d-block elements are metals with properties between those of s-block and p-block metals. Many d-block elements form cations in more than one oxidation state. 

Iron as a transition element Why is iron a transition metal To understand this we need to look at the periodic table of elements, where iron occupies a central position in the first row of d block elements. The properties of these elements are transitional between the metallic behaviour of the s-block elements and the variable valency of the p-block. But the variable valency of the transition metals is entirely different to that of the p-block elements. Whereas the latter have valencies that increase in steps of... 

Transition elements make up the lower left-central portion of the periodic table of the elements, bridging the s-block elements at the left and the p-block elements at the right. Five properties are commonly attributed to transition elements (1) they are all metals, (2) many of them form compounds involving a variety of oxidation states, (3) many of them form compounds and aqueous solutions that are colored, (4) many of them form complex ions, and (5) many of them form compounds exhibiting paramagnetic behavior. This experiment involves multiple oxidation states of several transition elements a variety of colored solutions, and several complex ions involving a transition metal cation and oxygen. 

E.g., cadmium, which lies directly below zinc, and lead, which hes directly below tin, are both highly toxic. However, cadmium appears to be an essential element for at least one organism, a marine diatom that produces a cadmium-specific enzyme that catalyzes the conversion of carbon dioxide and carbonic acid, as discovered in the year 2000. For further biological information on this element, see J. Emsley, Nature s Building Blocks, Oxford University Press, Oxford, 2001, pp. 74—76. This book is the standard reference for the detailed properties of all the elements, including their human, medical, economic, historical, environmental aspects. 

The major component of S-RM— rock block decides the structural characteristics on meso-level and controls the macro mechanical properties of S-RM. In order to investigate the influence of the rock block shape and specimen s lateral boundary conditions on the macro-mechanical properties of S-RM, this article simulated the deformation and strength properties of S-RM specimens with different rock block shapes and different lateral boundary types in the two-dimensional biaxial compression tests using discrete element method. The numerical simulation conditions are shown in Table 1. The grading curve of rock blocks in specimen is shown in Figure 1. 

The physical and chemical properties of the chemical elements are a consequence of their electronic structure. The chemistry of metals and of their compounds show the existence of analogies for metals that have to fill s, p, d, or f subshells. Therefore, those elements that have the same value of the second quantum number (1) (see Section 2.3.1) are classified in the s, p, d, f blocks of elements (Figure 2.2). 

The s-block metal that lies immediately before the first row of d-block elements in the Periodic Table is calcium (Ca), in Group 2. When we compare the properties of calcium with the first row of transition elements we find some differences despite the fact that they are all metals. You need to know the following comparisons ... 

Oxygen is the most abundant element on earth The earths crust is rich in carbonate and sili cate rocks the oceans are almost entirely water and oxygen constitutes almost one fifth of the air we breathe Carbon ranks only fourteenth among the elements in natural abundance but trails only hydro gen and oxygen in its abundance in the human body It IS the chemical properties of carbon that make it uniquely suitable as the raw material forthe building blocks of life Let s find out more about those chemi cal properties... 

Besides the chemical composition, porosity is another property of stone which has great influence on its preservation. An increased porosity increases the exposed surface and pores allow movement of materials such as water and its solutes through the stones. If the pores are blocked or reduced in diameter such substances may be trapped within resulting in increased local interior damage. Exposure to the climatic elements is one important source of decay. Freeze-thaw cycles, in particular, result in pressures on the pore walls of the stone s interior from changes in volume during the phase transition... 

Elements on the left of the p block, especially the heavier elements, have ionization energies that are low enough for these elements to have some of the metallic properties of the members of the s block. However, the ionization energies of the p-block metals are quite high, and they are less reactive than those in the s block. The elements aluminum, tin, and lead, which are important construction materials, all lie in this region of the periodic table (Fig. 1.61). 

All d-block elements are metals (Fig. 1.63). Their properties are transitional between the s- and the p-block elements, which (with the exception of the members of Group 12) accounts for their alternative name, the transition metals. Because transition metals in the same period differ mainly in the number of /-electrons, and these electrons are in inner shells, their properties are very similar. 

The elements in Groups 3 through 11 are called the transition metals because they represent a transition from the highly reactive metals of the s block to the much less reactive metals of Group 12 and the p block (Fig. 16.1). Note that the transition metals do not extend all the way across the d block the Group 12 elements (zinc, cadmium, and mercury) are not normally considered to be transition elements. Because their d-orbitals are full, the Group 12 elements have properties that are more like those of main-group metals than those of transition metals. Just after... 

The elements that can form cations relatively easily are metals. All metals have similar properties, in part because their outermost s electrons are relatively easy to remove. All elements in the s block have ns or n s valence configurations. The d-block elements have one or two n S electrons and various numbers of (n - 1) d electrons. Examples are titanium (4 S 3 d ) and silver (5 Ad ). Elements in the f block have two S electrons and a... 

Although zinc is formally a 4-block element, some of its chemical properties are similar to those of the alkaline earth metals, especially those of magnesium. This is mainly due to zinc s exclusive exhibition of the +2 oxidation state in all its compounds and its appreciable electropositive character. With a standard potential of —0.763 V, zinc is considerably more electropositive than copper and cadmium. 

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