46 Facts About Alkali metals

Alkali metals consist of the chemical elements lithium, sodium, potassium, rubidium, caesium, and francium .

All alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties.

Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour.

Alkali metals are all shiny, soft, highly reactive metals at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1.

All the alkali metals react with water, with the heavier alkali metals reacting more vigorously than the lighter ones.

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All of the discovered alkali metals occur in nature as their compounds: in order of abundance, sodium is the most abundant, followed by potassium, lithium, rubidium, caesium, and finally francium, which is very rare due to its extremely high radioactivity; francium occurs only in minute traces in nature as an intermediate step in some obscure side branches of the natural decay chains.

Sodium, potassium and lithium are essential elements, having major biological roles as electrolytes, and although the other alkali metals are not essential, they have various effects on the body, both beneficial and harmful.

Alkali metals's version put all the alkali metals then known, as well as copper, silver, and thallium, together into a group.

All the alkali metals have odd atomic numbers and they are not as common as the elements with even atomic numbers adjacent to them in the Solar System.

The heavier alkali metals are less abundant than the lighter ones as the alkali metals from rubidium onward can only be synthesised in supernovae and not in stellar nucleosynthesis.

Physical and chemical properties of the alkali metals can be readily explained by their having an ns valence electron configuration, which results in weak metallic bonding.

The ns configuration results in the alkali metals having very large atomic and ionic radii, as well as very high thermal and electrical conductivity.

Alkali metals are more similar to each other than the elements in any other group are to each other.

For instance, when moving down the table, all known alkali metals show increasing atomic radius, decreasing electronegativity, increasing reactivity, and decreasing melting and boiling points as well as heats of fusion and vaporisation.

Stable alkali metals are all silver-coloured metals except for caesium, which has a pale golden tint: it is one of only three metals that are clearly coloured .

All the alkali metals are highly reactive and are never found in elemental forms in nature.

The alkali metals react with water to form strongly alkaline hydroxides and thus should be handled with great care.

The heavier alkali metals react more vigorously than the lighter ones; for example, when dropped into water, caesium produces a larger explosion than potassium if the same number of moles of each metal is used.

The alkali metals have the lowest first ionisation energies in their respective periods of the periodic table because of their low effective nuclear charge and the ability to attain a noble gas configuration by losing just one electron.

Not only do the alkali metals react with water, but with proton donors like alcohols and phenols, gaseous ammonia, and alkynes, the last demonstrating the phenomenal degree of their reactivity.

Second ionisation energy of all of the alkali metals is very high as it is in a full shell that is closer to the nucleus; thus, they almost always lose a single electron, forming cations.

All the alkali metals have odd atomic numbers; hence, their isotopes must be either odd–odd or odd–even .

Alkali metals are more similar to each other than the elements in any other group are to each other.

For instance, when moving down the table, all known alkali metals show increasing atomic radius, decreasing electronegativity, increasing reactivity, and decreasing melting and boiling points as well as heats of fusion and vaporisation.

Since the outermost electron of alkali metals always feels the same effective nuclear charge, the only factor which affects the first ionisation energy is the distance from the outermost electron to the nucleus.

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Second ionisation energy of the alkali metals is much higher than the first as the second-most loosely held electron is part of a fully filled electron shell and is thus difficult to remove.

Therefore, the falling melting and boiling points of the alkali metals indicate that the strength of the metallic bonds of the alkali metals decreases down the group.

Alkali metals all have the same crystal structure 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.

All the alkali metals react vigorously or explosively with cold water, producing an aqueous solution of a strongly basic alkali metal hydroxide and releasing hydrogen gas.

The alkali metal borides tend to be boron-rich, involving appreciable boron–boron bonding involving deltahedral structures, and are thermally unstable due to the alkali metals having a very high vapour pressure at elevated temperatures.

The lattice energy is maximised with small, highly charged ions; the alkali metals do not form highly charged ions, only forming ions with a charge of +1, so only lithium, the smallest alkali metal, can release enough lattice energy to make the reaction with nitrogen exothermic, forming lithium nitride.

All the alkali metals react readily with phosphorus and arsenic to form phosphides and arsenides with the formula M3Pn .

All the alkali metals react vigorously with oxygen at standard conditions.

Smaller alkali metals tend to polarise the larger anions due to their small size.

Alkali metals can react analogously with the heavier chalcogens, and all the alkali metal chalcogenides are known .

Alkali metals are among the most electropositive elements on the periodic table and thus tend to bond ionically to the most electronegative elements on the periodic table, the halogens, forming salts known as the alkali metal halides.

Alkali metals react similarly with hydrogen to form ionic alkali metal hydrides, where the hydride anion acts as a pseudohalide: these are often used as reducing agents, producing hydrides, complex metal hydrides, or hydrogen gas.

Organometallic compounds of the higher alkali metals are even more reactive than organosodium compounds and of limited utility.

Similarly, the alkali metals react with cyclooctatetraene in tetrahydrofuran to give alkali metal cyclooctatetraenides; for example, dipotassium cyclooctatetraenide is an important precursor to many metal cyclooctatetraenyl derivatives, such as uranocene.

Alkali metals react with halogen derivatives to generate hydrocarbon via the Wurtz reaction.

Coinage metals were traditionally regarded as a subdivision of the alkali metal group, due to them sharing the characteristic s electron configuration of the alkali metals .

Finally, the alkali metals are at the top of the electrochemical series, whereas the coinage metals are almost at the very bottom.

Production of pure alkali metals is somewhat complicated due to their extreme reactivity with commonly used substances, such as water.

The heavier alkali metals are more typically isolated in a different way, where a reducing agent is used to reduce the alkali metal chloride.

Pure alkali metals are dangerously reactive with air and water and must be kept away from heat, fire, oxidising agents, acids, most organic compounds, halocarbons, plastics, and moisture.

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The alkali metals must be stored under mineral oil or an inert atmosphere.