Periodic table main groups

A FIGURE 2.13 The Periodic Table Main-Group and Transition Elements The elements in the periodic table fall into columns. The two columns at the left and the six columns at the right comprise the main-group elements. Each of these eight columns is a group or family. 

A plot of density versus element is given below (table only shows a few elements used in the plot. Density clearly is a periodic property for these two periods of main group elements. It rises, falls a bit, rises again, and falls back to the axis, in both cases. 

Patterns in chemical reactivity of the elements correlate with patterns in the physical structure of the atom they are both periodic functions of Z. Reading across the periodic table (horizontally) shows that each main-group element (Groups I-VIII) in Period 3 has exactly 8 more electrons than the element immediately above it in Period 2. Similarly, each main-group element in Periods 4 and 5 has exactly 18 more electrons than the corresponding element in the period above. The sequence of numbers, 8, 8, 18, 18, and so forth, that organize the periodic table into groups (columns), whose elements have similar physical and chemical properties, arises from the quantum theory of atomic structure (see discussion in Chapter 5). 

Main-group (representative) elements elements in the groups labeled 1, 2, 3, 4, 5, 6, 7, and 8 on the periodic table. The group number gives the sum of the valence s and p electrons. 

Main group elements are those in the A groups of the periodic table, or Groups 1, 2, and 13 to 18 by the lUPAC system. The B groups (3 to 12) are transition elements (Section 5.6). 

The properties of the head element of a main group in the periodic table resemble those of the second element in the next group. Discuss this diagonal relationship with particular reference to (a) lithium and magnesium, (b) beryllium and aluminium. 

As indicated in Figure 4, the early transactinide elements find their place back in the main body of the Periodic Table. The discoverers of the currendy known transactinide elements, suggested names and symbols, and dates of discovery are Hsted in Table 10 (19). Because there are competing claims for the discovery of these elements, the two groups of discoverers in each case have suggested names for elements 104 and 105. In the case of elements 106—109, names for the elements have not been suggested in order to avoid another dupHcation. 

Tellurium [13494-80-9] Te, at no. 52, at wt 127.61, is a member of the sixth main group. Group 16 (VIA) of the Periodic Table, located between selenium and polonium. Tellurium is in the fifth row of the Table, between antimony and iodine, and has an outer electron configuration of The four inner... 

The strength of an acid depends on the atom to which the proton is bonded. The two main factors are the strength of the H—X bond and the electronegativity of X. Bond strength is more important for atoms in the sfflne group of the periodic table, electronegativity is more important for atoms in the same row. Electronegative atoms elsewhere in the molecule can increase the acidity by inductive effects. 

Nitrogen forms binary compounds with almost all elements of the periodic table and for many elements several stoichiometries are observed, e.g. MnN, Mn Ns, Mn3N2, MniN, Mn4N and Mn tN (9.2 < jc < 25.3). Nitrides are frequently classified into 4 groups salt-like , covalent, diamond-like and metallic (or interstitial ). The remarks on p. 64 concerning the limitations of such classifications are relevant here. The two main methods of preparation are by direct reaction of the metal with Ni or NH3 (often at high temperatures) and the thermal decomposition of metal amides, e.g. ... 

The radii of cations and anions derived from atoms of the main-group elements are shown at the bottom of Figure 6.13. The trends referred to previously for atomic radii are dearly visible with ionic radius as well. Notice, for example, that ionic radius increases moving down a group in the periodic table. Moreover the radii of both cations (left) and anions (right) decrease from left to right across a period. 

In what main group(s) of the periodic table do element(s) have the following number of filled p orbitals in the outermost principal level ... 

These structures (without the circles) are referred to as Lewis structures. In writing Lewis structures, only the valence electrons written above are shown, because they are the ones that participate in covalent bonding. For the main-group elements, the only ones dealt with here, the number of valence electrons is equal to the last digit of the group number in the periodic table (Table 7.1). Notice that elements in a given main group all have the same number of valence electrons. This explains why such elements behave similarly when they react to form covalently bonded species. 

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