To gain a better knowledge of the properties of objects and the dangers they are exposed to, it is important to have a better insight in their composition and the processes that have a negative impact on them.
This insight demands a basic knowledge of chemistry, physics and biology. Because not everybody involved in art and cultural heritage has this knowledge (maybe because it was never learned or maybe partly forgotten) we want to provide this basic knowledge through our blog/site. Sometimes we use a more simplified way for a better understanding.
Today we start with “THE ATOM”.
What is an atom?
The word “atom” is derived from the Greek word “atomos” which means ‘indivisible”. The ancient Greeks thought the atom was the smallest particle in the universe and that it was indevisible. Today this idea is outdated.
But the atom remains the smallest building block of which all matter and materials, as well vegetable as animal or mineral are composed of. Atoms are the “lego blocks” of nature. There are different kinds of atoms. They have a different composition and different properties and can be combined to form living materials or non-living materials. The way they combine happens according to coded instructions inherent to nature. These instructions can be of a physical or chemical nature. They are a kind of “manuals” according to which the building blocks are combined to form an entity. Because these “manuals” are often more “guidelines” instead of a strict program, it is possible to find a lot of variations on the theme, especially in living materials. Living creatures or objects composed from once living matter we call “organic”. Non-living materials we call “inorganic” (= non-organic).
How is an atom structured?
Atoms have a diameter of about one tenth of a million of one millimeter. This is very small and invisible for the naked eye even using a normal laboratory microscope.
An atom consists of smaller particles of which we will only mention the ones most important to our purpose: protons, neutrons and electrons. The most simple representation of an atom is comparable to our solar system: a central core (consisting of protons and neutrons) around which circulate smaller objects (electrons). In practice the system is more complicated. The electrons move at a crazy speed aorund the core and not in planetary orbit as our planets, but criss-cross through a spherical or elliptical space around the atom core.
Representation of atom (Adrien Facélina)
The amount of protons can be equal or not to the amount of neutrons. In an atom there are always as many protons as electrons. Protons have a positive electrical charge, electrons a negative electrical charge. This way the particles keep each other balanced. Neutrons do not have electrical charges.
The core of an atom is very small. The diameter is about 1/1000 of the total diameter of the atom. The electrons are smaller still. Everything in between is empty space, which allows for a lot of movement. All objects, even living creatures are thus composed of a lot of empty space.
There is a whole variation of atoms. This is based, amongst others, on the different amount of protons and neutrons in the core. The properties of these atoms are therefore different. Atoms can contain up to 92 protons. Based on the amount of protons the atoms have received what we call an “atom number”. All these atoms occur in nature. Number 92 is uranium. Every type of atom has specific properties and behaviour and react in specific ways with other atoms. There are also atoms with a higher atom number (up to 118 nowadays), but these atoms are not occurring spontaneously in nature. They can only be synthesized with scientific equipment.
The table of Mendelejev
Based on the diversity of properties the Russian Dmitri Mendelejev devised a clear table of elements for all known atoms in his time. Elements have been added to this table when they became available. This table shows the various relations between the different atoms.
Table of Mendelejev (DePiep)
Names and symbols
Each atom is represented by a letter symbol. Mostly, but not always these are the first letter(s) of the Greek or Latin name for the atom. So the letter H stands for Hydrogenium (Hydrogen), He for Helium (Helium) and Cl for Chloros (Chlorine).
In conservation practice we will encounter often the same atoms. That is why it is important to know the exact names, shortenings and properties of these atoms. Lacking the right knowledge can have a large impact on conservation and survival of materials.
The most occurring atoms we will work with are: H (hydrogen), C (carbon), N (nitrogen), O (oxygen), P (phosphor), S (sulfur), Cl (chlorine). Depending on the materials we work with we will also need knowledge of Na (sodium), Mg (magnesium), Al (aluminium), Si (silicium), K (potassium), Ca (calcium), Fe (iron), Ni (nickel), Cu (copper), Zn (zinc), Ag (silver), Sn (tin), Au (gold) and Pb (lead).
In a next post we will cover the interaction between identical and non-identical atoms.
Guy De Witte
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