Group 1 elements and reactions

• The first ionization energy is the amoun molecule. or atomt of energy required to remove one electron from an
• Atomic radius increases down the group. The radius of an atom is governed by

  the number of layers of electrons around the nucleus

  • the pull the outer electrons feel from the nucleus

  Going down the group, each successive element in a group has an extra filled shell of

  electrons.

  These filled shells are effective at shielding the valence electrons from the attraction of the

  nucleus.
• The alkali metals include Li, Na, K, Rb, Cs, and Fr.
• The electronic configuration of Li is 1s22s1.
• The electronic configuration of Na is 1s22s22p6.
• The electronic configuration of K is 1s22s22p63s23p64s1.
• The electronic configuration of Rb is [Kr]5s1.
• The electronic configuration of Cs is 6s1.
• The electronic configuration of Fr is 7s1.
• Atomization energy falls as the atomic radius increases and as the length of the metallic bond increases.
• Lithium, sodium and potassium are stored in oil.
• This means that the delocalized electrons are further from the attraction of the nuclei in the bigger atoms, leading to lower activation energies and therefore faster reactions.
• Group 1 elements are very reactive metals and have to be stored out of contact with air to prevent their oxidation.
• Rubidium is denser than water and sinks, reacting violently and immediately, with everything spitting out of the container again.
• Potassium hydroxide and hydrogen are formed when potassium reacts with water.
• Francium in water releases radioactive material and explodes, producing a hydroxide and hydrogen gas.
• Potassium behaves like sodium except that the reaction is faster and enough heat is given off to set light to the hydrogen.
• Rubidium hydroxide solution and hydrogen are formed when rubidium reacts with water.
• This decrease in ionization energy is due to a decrease in atomicization energy, which is a measure of the strength of the metallic bond in each element.
• Reactivity increases with increasing atomic number because the energy needed to form positive ions falls as you go down the group.
• Reactivity increases down the group.
• Cesium explodes on contact with water, producing cesium hydroxide and hydrogen.
• Lithium burns with a strongly red-tinged flame if heated in air to give white lithium oxide.
• Sodium burns in air with an orange flame, giving a white solid mixture of sodium oxide and sodium peroxide.
• The color of a hydrogen flame is due to contamination with sodium compounds.
• Rubidium and cesium are stored in a sealed glass tube in a vacuum or in an inert gas like argon.
• The least soluble Group 1 carbonate is lithium carbonate which has a solubility of 1.3 g per 100 g of water at 20ºC.
• For this reason, Group 1 compounds are more thermally stable than those in Group 2.
• These hydrides are made by passing hydrogen gas over the heated metal.
• According to experimental evidence, all carbon to oxygen bonds in the CO32- ion are equivalent and the charges are spread out over the whole ion, although concentrated on the oxygen atoms.
• These hydrides are normally supplied as suspensions in mineral oil.
• The least soluble Group 1 hydroxide is lithium hydroxide which has a solubility of 12.8 g per 100 g of water.
• If this is heated, CO2 breaks free to leave the metal oxide.
• NaH(s) + H2O(l) → NaOH(aq) + H2(g)
• The solubility of the carbonates increases as you go down Group 1.
• The hydrides of Group 1 metals are white crystalline solids which contain the metal ions and hydride ions, H-.
• Down the group, the positive ions get bigger and the charge density decreases, resulting in a decrease in the polarizing effect of the positive ion on the carbonate ion.
• If the positive ion had only one positive charge, the polarizing effect would be less.
• These hydrides react violently with water releasing hydrogen gas and producing the metal hydroxide.
• If a positive ion comes next to a carbonate ion, it attracts the delocalized electrons in it towards itself, making the carbonate ion polarized.