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Reactivity then refers to the rate at which a chemical substance tends to undergo a chemical reaction in time. In pure compounds , reactivity is regulated by the physical properties of the sample. For instance, grinding a sample to a higher specific surface area increases its reactivity.
The Inhour equation used in nuclear reactor kinetics to relate reactivity and the reactor period. [1] Inhour is short for "inverse hour" and is defined as the reactivity which will make the stable reactor period equal to 1 hour (3,600 seconds). [2] Reactivity is more commonly expressed as per cent millie (pcm) of Δk/k or dollars. [3]
The reactivity series is sometimes quoted in the strict reverse order of standard electrode potentials, when it is also known as the "electrochemical series". [ 8 ] The following list includes the metallic elements of the first six periods.
The atomic number increases within the same period while moving from left to right, which in turn increases the effective nuclear charge. The increase in attractive forces reduces the atomic radius of elements. When we move down the group, the atomic radius increases due to the addition of a new shell. [5] [6] [7]
Their reactivity increases going down the group: while lithium, sodium and potassium merely burn in air, rubidium and caesium are pyrophoric (spontaneously catch fire in air). [84] The smaller alkali metals tend to polarise the larger anions (the peroxide and superoxide) due to their small size.
Ionization energy trends plotted against the atomic number, in units eV.The ionization energy gradually increases from the alkali metals to the noble gases.The maximum ionization energy also decreases from the first to the last row in a given column, due to the increasing distance of the valence electron shell from the nucleus.
The different rates are often a pedagogical demonstration of the reactivity–selectivity principle and the Hammond postulate. A bromine radical is not very reactive and the transition state for hydrogen abstraction has much radical character and is reached late. The reactive chlorine radical develops a transition state resembling the reactant ...
A period 2 element is one of the chemical elements in the second row (or period) of the periodic table of the chemical elements.The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases; a new row is started when chemical behavior begins to repeat, creating columns of elements with similar properties.