metals is the group of the periodic table that is known as the alkali metals.
which group of the periodic table is known as the alkali metals?
metals
from left to right across the four blocks of the long- or 32-column form of the periodic table are a series of linking or bridging groups of elements, located approximately between each block. these groups, like the metalloids, show properties in between, or that are a mixture of, groups to either side. chemically, the group 3 elements, scandium, yttrium, lanthanum and actinium behave largely like the alkaline earth metals or, more generally, "s" block metals but have some of the physical properties of "d" block transition metals. lutetium and lawrencium, at the end of the end of the "f" block, may constitute another linking or bridging group. lutetium behaves chemically as a lanthanide but shows a mix of lanthanide and transition metal physical properties. lawrencium, as an analogue of lutetium, would presumably display like characteristics. the coinage metals in group 11 (copper, silver, and gold) are chemically capable of acting as either transition metals or main group metals. the volatile group 12 metals, zinc, cadmium and mercury are sometimes regarded as linking the "d" block to the "p" block. notionally they are "d" block elements but they have few transition metal properties and are more like their "p" block neighbors in group 13. the relatively inert noble gases, in group 18, bridge the most reactive groups of elements in the periodic table—the halogens in group 17 and the alkali metals in group 1.
periodic table
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