Some Very Basic Chemistry What is a macromolecule?

All matter is made of small particles called atoms.   Atoms are far too small to be seen with the naked eye or even with a microscope.  In fact, more than a trillion atoms could fit over the period at the end of a sentence.  There are about 90 different kinds of atoms found in nature. Matter made up of all one kind of atom is called an element.
 

Some Familiar Elements and Their Symbols
Element	Symbol	Element	Symbol	Element	Symbol
Hydrogen	H	Phosphorous	P	Chlorine	Cl
Oxygen	O	Sulfur	S	Sodium	Na
Carbon	C	Magnesium	Mg	Gold	Au
Nitrogen	N	Silicon	Si	Tin	Sn

Clearly, however, there are more than 90 different kinds of matter in our world.  This is because atoms can combine in chemical reactions to produce a myriad of new substances.  For example, when one atom of sodium (which by itself is a soft metal) and one atom of chlorine (which by itself is a poison green gas) combine, the result is a compound called sodium chloride, more commonly known as table salt. A compound is made up of two or more elements that are chemically bonded.  

Na sodium		Cl chlorine		NaCl table salt

A molecule is the smallest particle of a compound that has all the properties of that compound.  We write the molecular formula of salt as NaCl to indicate it has one atom of sodium and one atom of chlorine.  

Since you may not wish to explore the complexities of chemical bonding as part of your genealogical research, you might find it useful to compare atoms to a variety of differently sized and shaped lego building blocks which can be fitted together in a variety of ways to form a multitude of different creations.   Similarly, the atoms of each element are distinguished by their mass and by the number of connections they can make with other atoms.  There is virtually an  infinite variety of compounds possible.

Some molecules are small, such as water, H₂O, which has only three atoms and table salt NaCl which has two.  Others are larger such as a molecule of table sugar, C₁₂H₂₂O₁₁ (sucrose) which has 45 atoms.  Still other molecules, such as proteins, are gigantic, sometimes containing tens of thousands of atoms. These gigantic molecules are called macromolecules.