Periodic table vertical groups

That Mendeleev was able to predict the properties of new elements helped convince many scientists of the accuracy of Dalton s atomic hypothesis. This in turn helped promote Dalton s proposed atomic nature of matter from a hypothesis to a more widely accepted theory. Mendeleev s chart, which ultimately led to our modern periodic table with its horizontal periods and vertical groups, also helped lay the groundwork for our understanding of atomic behavior and is recognized as one of the most important achievements of modern science. 

Periodic table An arrangement of the chemical elements in order of their atomic numbers. Arranged as horizontal periods and vertical groups or families of elements with similar properties. Its initiation is attributed to the nineteenth century Russian chemist Mendeleyev. A modem periodic table, which differs significantly from early ones, is shown on page 283. 

The shells, therefore, determine the shape of the periodic table, but there is more to the story than that. The existence of shells has another important effect the occupancy or partial occupancy of a shell dictates the chemical behavior, or the chemical reactivity, of the various elements. The vertical columns of the periodic table are groups of elements that share a similar condition of occupancy of their outermost shell and are therefore members of the same family, but families that share a common chemistry rather than a common ancestry. 

In the periodic table, the elements are arranged by atomic number into horizontal periods and vertical groups. Because of the periodic recurrence of certain key properties, elements within a group have similar behavior, whereas elements in a period have dissimilar behavior. Nonmetals appear in the upper-right portion of the table, metalloids lie along a staircase line, and metals fill the rest of the table. 

The vertical columns of elements represented in the periodic table are called groups, and the horizontal rows are called periods. There are seven periods in the periodic table. The groups are usually designated by roman numerals followed by the letter A or B as shown in the periodic table. 

In the periodic table, the elements are arranged by atomic number into horizontal periods and vertical groups. 

FIGURE 3-1 5 The periodic table. Vertical columns are called groups or families of elements. The elements within a group have similar properties. 

By considering the trends in the vertical groups of the Periodic Table, deduce possible answers to the following questions concerning the element astatine (At), atomic number 85. 

Physical Properties. Molybdenum has many unique properties, leading to its importance as a refractory metal (see Refractories). Molybdenum, atomic no. 42, is in Group 6 (VIB) of the Periodic Table between chromium and tungsten vertically and niobium and technetium horizontally. It has a silvery gray appearance. The most stable valence states are +6, +4, and 0 lower, less stable valence states are +5, +3, and +2. 

The nine elements, Fe, Ru, Os Co, Rh, Ir Ni, Pd and Pt, together formed Group VIII of Mendeleev s periodic table. They will be treated here, like the other transition elements, in vertical triads, but because of the marked horizontal similarities it is not uncommon for Fe, Co and Ni to be distinguished from the other six elements (known collectively as the platinum metals) and the two sets of elements considered separately. 

On the basis of observations such as these, we can say that the periodic table is an arrangement of elements, in order of increasing atomic number, in horizontal rows of such a length that elements with similar chemical properties fall directly beneath one another in vertical groups. 

This is, of course, the principle behind the structure of the periodic table. Elements within a given vertical group resemble one another chemically because chemical properties repeat themselves at regular intervals of 2,8,18, or 32 elements. 

Ground state The lowest allowed energy state of a species, 137 Group 1 metal. See Alkali metal Group 2 metal See Alkaline earth metal Group A vertical column of the periodic table, 31... 

Suffice it to say that Dobereiner s research established the notion of triads as a powerful concept, which several other chemists were soon to take up with much effect. Indeed, Do-bereiner s triads, which would appear on the periodic table grouped in vertical columns, represented the first step in fitting the elements into a system that would account for their chemical properties and would reveal their physical relationships. 

What will now be proposed is that in addition to its role in ordering the elements, the quantity Z may be used to also affect a secondary classification of the elements, that is, their placement into vertical groups in the sense of the conventional periodic table. In proposing this idea, I make use of what was historically the earliest hint of chemical periodicity, namely, the existence of triads of elements [35]. 

The last vertical column of the eighth group of the Periodic Table of the Elements comprises the three metals nickel, palladium, and platinum, which are the catalysts most often used in various reactions of hydrogen, e.g. hydrogenation, hydrogenolysis, and hydroisomerization. The considerations which are of particular relevance to the catalytic activity of these metals are their surface interactions with hydrogen, the various states of its adatoms, and admolecules, eventually further influenced by the coadsorbed other reactant species. 

Periodic table A chart that arranges the elements by atomic number in a way that the vertical columns produce groups of elements with similar valence electron configurations and chemical properties. 

The periodic table is an extremely useful tabulation of the elements. It is constructed in a manner such that each vertical column contains elements which are chemically similar. The elements in the columns are called groups or families. (Elements in some of the groups arc very similar to each other. Elements in others of the groups are less similar. For example, the elements of the first group resemble each other more than the elements of the fourth group from the end, headed by N.) Each row in the table is called a period (Fig. 3-1). 

Groups or families are the vertical rows on the periodic table. They may be labeled in two ways. The older way involves a Roman numeral and a letter, either A or B. We call the groups labeled with an A the main-group elements, while the B groups are the transition elements. Two horizontal groups, the inner transition elements, belonging to periods 6 and 7 are normally pulled out of the main body of the periodic table and are placed at the bottom of the table. 

Groups or families are the vertical rows on the periodic table the elements have similar properties. 

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