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A substance that does not conduct electricity at low temperatures but does so at higher temperatures.

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Delocalization

Of electrons, refers to bonding electrons that are distributed among more than two atoms that are bonded together, occurs in species that exhibit resonance.
The formation of a set of molecular orbitals that extend over more than two atoms, important in species that valence bond theory describes in terms of resonance.

Alkaline Battery

A dry cell in which the electrolyte contains KOH.

Mixture

A sample of matter composed of two or more substances, each of which retains its identity and properties.

Combination Reaction

Reaction in which two substances (elements or compounds) combine to form one compound.

Supersaturated Solution

A solution that contains a higher than saturation concentration of solute, slight disturbance or seeding causes crystallization of excess solute.

Heat of Solution

The amount of heat absorbed in the formation of solution that contains one mole of solute, the value is positive if heat is absorbed (endothermic) and negative if heat is released (exothermic).

Metal

An element below and to the left of the stepwise division (metalloids) in the upper right corner of the periodic table, about 80% of the known elements are metals.

How to make crystal glass

From history we know that the idea of creating crystal belongs to the British: they were the first to add lead oxides to the charge material, and as a result got glass with unusual “voice”, transparency and sparkling faces. Classical crystal contains 24% of lead oxide, but there are products with a higher content of up to 30%.

Indicators

For acid-base titrations, organic compounds that exhibit different colors in solutions of different acidities, used to determine the point at which reaction between two solutes is complete.

Cloud Chamber

A device for observing the paths of speeding particiles as vapor molecules condense on them to form foglike tracks.