Ions and compounds

Atoms are made up of neutrons that are neutral and have no charge, protons with a positive charge andelectrons with a negative charge.

An ion is an entity or a group of atoms with a positive or negative charge such as the positively charged hydrogen ion H+ and thenegatively charged nitrate ion NO3-. Negatively charged ions are also called anions while positively charged ions are called cations.

A compound is something that is made up oftwo or more simple substances. Ammonia NH3 is a compound without a charge.

Atom model

Below it is shown how positively charged protons (yellow) and neutral neutrons constitutes a nucleusin the atom while the negatively charges electrons orbits the nucleus. This is a very simple model of the atom.A more complicated model would include a nucleus surrounded by orbitals with electrons in them orbiting the nucleus.

Web resources

A philosophical approach to atoms
A full course about atoms and ions
Encarta - encyclopedia

Ions and compounds

Buffers and Equilibriums

Buffers and Equilibriums As shortly explained in the section about how to calculate pH in a solution of dissolved NaHCO3, a buffer has the capability of keeping pH withina certain and narrow range even if an excess of hydrogen ions H+ or hydroxide ions OH- are added. In this particular page I will elaborate a bit on why buffers actually have the ca...

pH meter pH strips

pH meter pH strips Background pH meters have been used since 1936 when they were invented by the Danish company Radiometer.In contrast to many other measuring devices pH meters do not measure concentrations, rather they measure activities. Tobe more specific the pH meter does not measure the concentration of hydrogen ions. pH meters are used to ...

An introduction to Ionic Strength

An introduction to Ionic Strength Background To quantify the effect of inter-ionic interactions, such as molecular attraction and repelling, one has to have a `parameter` describing themagnitude of these forces and how they alter the way certain calculation are done. Topic: Equilibriums The pH s...

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Gases - the ideal gas law explained Chemical compounds in aqueous solutions are fairly easy to handle as their quantities can either be expressed in weight such as grams or kilos, moles perliter (molarity) or moles per kg (molality). Topic: pKa & Ka The basics ...