The elements within the same team of the periodic table tend to exhilittle equivalent physical and also brianowens.tvical properties. Four major determinants influence retask of metals: nuclear charge, atomic radius, shielding effect and also sublevel plan (of electrons). Metal retask relates to ability to lose electrons (oxidize), create fundamental hydroxides, create ionic compounds with non-steels. In general, the bigger the atom, the better the capacity to shed electrons. The higher the shielding, the greater the capability to lose electrons. Thus, metallic character boosts going down the table, and decreases going throughout -- so the a lot of active metal is in the direction of the left and also dvery own.

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Group 1: The Alkali Metals

The word "alkali" is derived from an Arabic word interpretation "ashes". Many kind of sodium and potassium compounds were isolated from hardwood ashes (Na2CO3 and also K2CO3 are still periodically referred to as "soda ash" and "potash"). In the alkali group, as we go down the group we have actually facets Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr). Several physical properties of these elements are compared in Table (PageIndex1). These elements have all only one electron in their outera lot of shells. All the aspects show metallic properties and also have actually valence +1, therefore they provide up electron conveniently.

Table (PageIndex1): General Properties of Group I MetalsElementElectronic ConfigurationMelting Point (°C)Density (g/cm3)Atomic RadiusIonization Energy (kJ/mol)
Lithium(2s^1)1810.531.52520
Sodium(3s^1)980.971.86496
Potassium(4s^1)630.862.27419
Rubidium(5s^1)391.532.47403
Cesium(6s^1)281.882.65376

As we relocate down the group (from Li to Fr), the following patterns are observed (Table (PageIndex1)):

All have actually a solitary electron in an "s" valence orbitalThe melting suggest decreasesThe thickness increasesThe atomic radius increasesThe ionization power decreases (first ionization energy)

The alkali metals have the lowest (I_1) values of the elements

This represents the relative ease via which the lone electron in the outer "s" orbital deserve to be removed.

The alkali metals are extremely reenergetic, easily losing 1 electron to develop an ion with a 1+ charge:

Due to this retask, the alkali steels are discovered in nature only as compounds. The alkali steels incorporate straight via a lot of nonmetals:

React with hydrogen to form solid hydrides

<2M_(s) + H_2(g) ightarrowhead 2MH(s)>

(Note: hydrogen is present in the steel hydride as the hydride H- ion)

React with sulfur to create solid sulfides

<2M_(s) + S_(s) ightarrowhead M_2S_(s)>

React via chlorine to develop solid chlorides

<2M_(s) + Cl_2(g) ightarrowhead 2MCl_(s)>

Alkali steels react with water to create hydrogen gas and also alkali steel hydroxides; this is a really exothermic reaction (Figure (PageIndex1)).

<2M_(s) + 2H_2O_(l) ightarrow 2MOH_(aq) + H_2(g)>

*
Figure (PageIndex1): A little item of potassium steel explodes as it reacts through water. (CC SA-BY 3.0; Tavoromann)

The reaction between alkali steels and also oxygen is more complex:

A prevalent reaction is to form metal oxides which contain the O2- ion

<4Li_(s) + O_2 (g) ightarrowhead underbrace2Li_2O_(s)_ extlithium oxide>

Other alkali metals can create steel peroxides (consists of O22- ion)

<2Na(s) + O_2 (g) ightarrow underbraceNa_2O_2(s)_ extsodium peroxide>

K, Rb and Cs can additionally develop superoxides (O2- ion)


Colors through Absorption

The color of a brianowens.tvical is produced once a valence electron in an atom is excited from one power level to one more by visible radiation. In this situation, the particular frequency of light that excites the electron is absorbed. Therefore, the remaining light that you watch is white light devoid of one or even more wavelengths (hence appearing colored). Alkali metals, having actually lost their outera lot of electrons, have actually no electrons that deserve to be excited by visible radiation. Alkali metal salts and their aqueous solution are colormuch less unmuch less they contain a colored anion.

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Colors via Emission

When alkali metals are inserted in a flame the ions are diminished (acquire an electron) in the reduced part of the flame. The electron is excited (jumps to a greater orbital) by the high temperature of the flame. When the excited electron falls earlier down to a reduced orbital a photon is released. The transition of the valence electron of sodium from the 3p down to the 3s subshell outcomes in release of a photon with a wavesize of 589 nm (yellow)


Group 2: The Alkaline Earth Metals

Compared via the alkali steels, the alkaline earth steels are typically:

hardereven more densemelt at a higher temperature

The first ionization values (I1) of the alkaline earth metals are not as low as the alkali steels. The alkaline earth metals are therefore much less reenergetic than the alkali steels (Be and Mg are the least reenergetic of the alkaline earth metals). Several physical properties of these aspects are compared in Table (PageIndex2).

Table (PageIndex2): General Properties of Group 2 MetalsElementElectronic ConfigurationMelting Point (°C)Density (g/cm3)Atomic RadiusIonization Energy (kJ/mol)
Beryllium(2s^2)12781.851.52899
Magnesium(3s^2)6491.741.60738
Calcium(4s^2)8391.541.97590
Strontium(5s^2)7692.542.15549
Barium(6s^2)7253.512.17503

Calcium, and also aspects listed below it, react conveniently via water at room temperature:

The tendency of the alkaline earths to shed their 2 valence electrons is demonstrated in the reactivity of Mg in the direction of chlorine gas and oxygen:

<2Mg_(s) + O_2(g) ightarrowhead 2MgO_(s)>

The 2+ ions of the alkaline earth steels have a noble gas choose electron configuration and are therefore create colorless or white compounds (unmuch less the anion is itself colored). Flame colors:

Calcium: brick redStrontium: crimkid redBarium: green

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