Group I - Alkali Metals

Alkali Metals

Li, Na, K, Rb, Cs, Fr

appearance of alkali metals

soft silvery metals that give basic solutions

Bonding in alkali metals

M-M bonding is weak; gives delocalization of electrons which can surround a sea of cations

Isolation of Sodium

electrolysis of molten NaCl by the Down’s Process

the Down’s Process

Cl gas is given off at a graphite anode and molten sodium collects at a steel cathode; CaCl2 is added to NaCl to lower its melting point from 800 to about 630 degrees C

Isolation of Potassium metal

Melt Reaction, reaction of KCl with sodium metal to give NaCl and K

uses of alkali metals

form M+ ions which act as good reducing agents, alloys of Na and K are used in nuclear reactants as coolants, francium is used in reactive tracer experiments, Na+/K+ have physiological importance, Li+ used in treatment of bipolar disorder and in batteries

Chemical Properties of Alkali Metals

all reduce alcohols and water, reactivity increasing down the group due to greater ease of ionization

Na in ammonia

Na (and other alkalki metals) are soluble and will lose an electron in this liquid

Alkali metals and Oxygen

heating these metals in oxygen gas produces different products depending on the size of the cation

Li + O2

Oxide, Li2O

Na + O2

Na2O2, peroxide

K + O2 (and above)

superoxide, KO2

NaCl

vast deposits in oceans and deserts, starting material for sodium hydroxide

K+

less soluble than Na+ and less easily leached from minerals, selectively filtered out by plants

NaOH

soft waxy, corrosive solid, commonly used as a base, produces by electrolysis of brine

Na2SO4

used in paper making and detergents, formed by reaction of H2SO4 (bronsted acid) and NaCl

NaHCO3

baking soda, washing power, released CO2 on reaction with acid

reaction of M with H2

forms MH for all M

reaction of M with O2

forms Li2O

forms Na2O2

forms KO2

reaction of M with N2

forms Li3N, only works for Li

reaction of M with X2, a halogen

forms MX for all M

Reaction of M with H20

forms MOH and Hydrogen Gas for all M