The aspects within the same group of the routine table have tendency to exhibit similar physical and smashville247.netical properties. Four major factors affect reactivity that metals: atom charge, atomic radius, shielding effect and sublevel arrangement (of electrons). Metal reactivity relates to capability to lose electrons (oxidize), kind basic hydroxides, form ionic compounds v non-metals. In general, the enlarge the atom, the better the capability to lose electrons. The better the shielding, the higher the capacity to shed electrons. Therefore, metallic character increases going under the table, and also decreases going throughout -- so the most energetic metal is in the direction of the left and also down.

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Group 1: The Alkali Metals

The word "alkali" is acquired from one Arabic word meaning "ashes". Plenty of sodium and also potassium compounds to be isolated from timber ashes (Na2CO3 and K2CO3 space still occasionally referred to together "soda ash" and "potash"). In the alkali group, together we go under the team we have elements Lithium (Li), salt (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr). Several physical nature of these elements are contrasted in Table (PageIndex1). These aspects have all just one electron in your outermost shells. All the aspects show metallic properties and also have valence +1, thus they provide up electron easily.

Table (PageIndex1): basic Properties of group I MetalsElementElectronic ConfigurationMelting suggest (°C)Density (g/cm3)Atomic RadiusIonization power (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 team (from Li to Fr), the adhering to trends space observed (Table (PageIndex1)):

All have actually a single electron in one "s" valence orbitalThe melting point decreasesThe thickness increasesThe atom radius increasesThe ionization energy decreases (first ionization energy)

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

This to represent the family member ease with which the lone electron in the outer "s" orbital deserve to be removed.

The alkali metals are very reactive, readily shedding 1 electron to form an ion v a 1+ charge:

Due to this reactivity, the alkali metals are found in nature only as compounds. The alkali metals combine directly with many nonmetals:

React through hydrogen to form solid hydrides

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

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

React with sulfur to form solid sulfides

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

React v chlorine to form solid chlorides

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

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

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

*
Figure (PageIndex1): A little piece that potassium steel explodes as it reacts with water. (CC SA-BY 3.0; Tavoromann)

The reaction in between alkali metals and oxygen is more complex:

A usual reaction is to type metal oxides i beg your pardon contain the O2- ion

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

Other alkali metals can type metal peroxides (contains O22- ion)

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

K, Rb and Cs can also type superoxides (O2- ion)


Colors via Absorption

The shade of a smashville247.netistry is developed when a valence electron in one atom is excited from one power level to one more by clearly shows radiation. In this case, the particular frequency that light that excites the electron is absorbed. Thus, the remaining light the you see is white irradiate devoid that one or more wavelengths (thus showing up colored). Alkali metals, having actually lost your outermost electrons, have actually no electrons that have the right to be excited by visible radiation. Alkali metal salts and their aqueous solution are colorless uneven they save a fancy anion.

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Colors via Emission

When alkali metals are placed in a flame the ions are lessened (gain one electron) in the lower part of the flame. The electron is excited (jumps to a higher orbital) by the high temperature the the flame. When the excited electron falls earlier down come a lower orbital a photon is released. The shift of the valence electron of sodium from the 3p down to the 3s subshell outcomes in release of a photon v a wavelength that 589 nm (yellow)


Group 2: The Alkaline earth Metals

Compared v the alkali metals, the alkaline planet metals room typically:

hardermore densemelt in ~ a higher temperature

The very first ionization worths (I1) of the alkaline earth metals room not as low as the alkali metals. The alkaline earth metals are therefore less reactive 보다 the alkali steels (Be and also Mg space the the very least reactive that the alkaline planet metals). Several physical properties of these elements are contrasted in Table (PageIndex2).

Table (PageIndex2): basic Properties of group 2 MetalsElementElectronic ConfigurationMelting suggest (°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 elements listed below it, react conveniently with water at room temperature:

The propensity of the alkaline earths to shed their two valence electron is prove in the reactivity the Mg towards chlorine gas and oxygen:

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

The 2+ ions of the alkaline planet metals have actually a noble gas like electron configuration and are thus type colorless or white compounds (unless the anion is chin colored). Fire colors:

Calcium: brick redStrontium: crimson redBarium: green

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