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Representation of the core of a molecule, ion or formula unit by showing atomic symbols and only outer shell electrons.

Latest Articles

  • Ozone

    We breathe 24 hours a day, 7 days a week, consuming about 25 kg of air every day. It turns out that we practically predetermine our health by the air we breathe.

  • Diamonds Are Forever

    Diamonds are still a girl's best friend, right? We love the shiny gems. They are the most popular rocks sold today. But what exactly are they, anyway? Where do they come from? What else are they used for?

  • Protein Design: Automated protein discovery and synthesis

    In this paper I describe (theoretically) the method(s) of automated protein discovery and synthesis.

  • Interesting facts about metals

    Metals have been used by people since ancient times. All the time the process of obtaining them was improved, useful alloys of various metals appeared. Let’s look at interesting facts about metals.

  • The most expensive metal in the world

    Do you think the most expensive metal is gold? No! On earth there are more valuable metals. But we need to divide the value of metals that occur in nature, and metals - isotopes, which are obtained in special laboratories. Let’s look at natural metals first.

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Zone Refining

A method of purifying a bar of metal by passing it through an induction heater, this causes impurties to move along a melted portion. This method applies the fact when a metal crystallizes on cooling, impurities are automatically expelled as they do not form part of the crystal.

What are Compound Microscopes?

Most of the microscopes used today are compound. A compound microscope features two or more lenses. A hollow cylinder called the tube connects the two lenses.

The top lens, the one people look through, is called the eyepiece. The bottom lens is known as the objective lens. Below the two lenses is the stage, with the illuminator below that.

Mass Action Expression

For a reversible reaction, aA + bB cC + dD the product of the concentrations of the products (species on the right), each raised to the power that corresponds to its coefficient in the balanced chemical equation, divided by the product of the concentrations of reactants (species on the left), each raised to the power that corresponds to its coefficient in the balanced chemical equation. At equilibrium the mass action expression is equal to K, at other times it is Q.[C]c[D]d [A]a[B]b = Q, or at equilibrium K.

Carbonium ion

An orgainic ion carrying a positive charge on a carbon atom.


Reaction of a substance with water.


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.

Dry Cells

Ordinary batteries (voltaic cells) for flashlights. radios, and so on, many are Leclanche cells.


Number of moles of solute per litre of solution.

Alkyl Group

A group of atoms derived from an alkane by the removal of one hydrogen atom.

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).