alkali metals are located in group 1 on the periodic table.
alkali metals are located in group 1 on the periodic table.
where are alkali metals located on the periodic table?
group 1
thallium is the heaviest stable element in group 13 of the periodic table. at the bottom of the periodic table, the inert pair effect is quite strong, because of the relativistic stabilisation of the 6s orbital and the decreasing bond energy as the atoms increase in size so that the amount of energy released in forming two more bonds is not worth the high ionisation energies of the 6s electrons. it displays the +1 oxidation state that all the known alkali metals display, and thallium compounds with thallium in its +1 oxidation state closely resemble the corresponding potassium or silver compounds stoichiometrically due to the similar ionic radii of the tl (164 pm), k (152 pm) and ag (129 pm) ions. it was sometimes considered an alkali metal in continental europe (but not in england) in the years immediately following its discovery, and was placed just after caesium as the sixth alkali metal in dmitri mendeleev's 1869 periodic table and julius lothar meyer's 1868 periodic table. (mendeleev's 1871 periodic table and meyer's 1870 periodic table put thallium in its current position in the boron group and left the space below caesium blank.) however, thallium also displays the oxidation state +3, which no known alkali metal displays (although ununennium, the undiscovered seventh alkali metal, is predicted to possibly display the +3 oxidation state). the sixth alkali metal is now considered to be francium. while tl is stabilised by the inert pair effect, this inert pair of 6s electrons is still able to participate chemically, so that these electrons are stereochemically active in aqueous solution. additionally, the thallium halides (except tlf) are quite insoluble in water, and tli has an unusual structure because of the presence of the stereochemically active inert pair in thallium.
alkali metal
the alkali metals all have the same crystal structure (body-centred cubic) and thus the only relevant factors are the number of atoms that can fit into a certain volume and the mass of one of the atoms, since density is defined as mass per unit volume. the first factor depends on the volume of the atom and thus the atomic radius, which increases going down the group; thus, the volume of an alkali metal atom increases going down the group. the mass of an alkali metal atom also increases going down the group. thus, the trend for the densities of the alkali metals depends on their atomic weights and atomic radii; if figures for these two factors are known, the ratios between the densities of the alkali metals can then be calculated. the resultant trend is that the densities of the alkali metals increase down the table, with an exception at potassium. due to having the lowest atomic weight and the largest atomic radius of all the elements in their periods, the alkali metals are the least dense metals in the periodic table. lithium, sodium, and potassium are the only three metals in the periodic table that are less dense than water: in fact, lithium is the least dense known solid at room temperature.
alkali metal