The ninety-odd substances that nothing can break down any further — and why an essential oil is built from only three of them.
~11 min read
Pick up a piece of charcoal. You can crush it to powder, burn it, dissolve what is left in acid, heat it until it glows. At the end of every one of those operations, what you still have is carbon. No chemical procedure turns carbon into something simpler, because there is nothing simpler for it to turn into. That is what makes it an element.
An element is a substance made of only one kind of atom, which cannot be broken down into any simpler substance by chemical means. Both halves of that sentence do work. The first says what it is made of. The second says what you cannot do to it — and that half is far stricter than it sounds.
Chemistry has a great many ways of taking things apart: heat, water, acid, alkali, a current, enzymes. Every one succeeds on almost everything and fails on an element. Water is the example that catches people, because it looks as simple as a substance can look. Run a current through it and it comes apart into hydrogen and oxygen, in a fixed two-to-one ratio by volume, every time. Water is not an element. It is two of them, bonded.
The test rules out far more than it lets in. Steel is iron with carbon dissolved through it; air is mostly nitrogen and oxygen; table salt splits into a metal and a gas. An essential oil is hundreds of compounds sharing a bottle, which is why what an essential oil actually is takes a whole lesson. None of those is an element. They are [compounds and mixtures](#elements-versus-compounds).
What survives is a short list. Carbon, oxygen, hydrogen, nitrogen, iron, calcium, magnesium, gold — each one kind of atom, with nothing chemical reaching underneath it. Matter taught you that everything you can touch is made of chemicals; this is what those chemicals are made from.
The qualifier is honest rather than evasive. Chemistry is the business of rearranging which atoms are attached to which; it makes and breaks the bonds between atoms and never touches the nucleus at the centre of one. Within those rules, an element is the floor.
Nuclear processes play by other rules. Inside a star, or inside an unstable atom quietly decaying on a shelf, the nucleus itself changes and one element becomes another. The alchemists who spent centuries trying to turn lead into gold were not wrong that it can happen; they were wrong about the tools. Nothing in a kitchen, a distillery or a body comes near it — which is why an element cannot be destroyed by cooking, by digestion or by time. The iron in a meal is still iron on the far side of the body.
One hundred and eighteen elements have been named. Ninety-two occur in nature, from hydrogen to uranium. The rest exist because somebody made them, a few atoms at a time, in an accelerator, and they decay again within seconds. Real elements, and entirely irrelevant to a body or a bottle.
Symbols come from Latin rather than English — Fe from ferrum, Na from natrium, K from kalium — worth knowing when a supplement label uses one and a chemistry text the other. How the set is arranged, and why the arrangement predicts behaviour, is the periodic table.
Metals
Solid, hard, shiny, dense, good conductors. Iron, copper, gold. Most of the table is metal.
Metalloids
A small group sharing characteristics of both sides. Silicon and boron are the ones worth knowing.
Nonmetals
Poor conductors, low density, often gases at room temperature. Hydrogen, oxygen, nitrogen, carbon. Everything an essential oil is built from, and the great majority of a body, sits in this group.
Take a person of seventy kilograms and sort them by element. About forty-five of those kilograms are oxygen. Thirteen are carbon. Seven are hydrogen. Two are nitrogen. Those four are roughly ninety-six per cent of the mass of a human being, and the whole remainder — every mineral in every bone, every atom of iron in the blood — fits inside the last four per cent.
| Element | Share of body mass | Mostly present as |
|---|---|---|
| Oxygen | about 65% | Water, and the oxygen in most biological molecules |
| Carbon | about 18% | The backbone of every protein, fat, sugar and strand of DNA |
| Hydrogen | about 10% | Water again, and bonded to very nearly every carbon |
| Nitrogen | about 3% | Amino acids, and therefore every protein; also DNA |
| Calcium | about 1.5% | Bone and teeth, with a small, tightly held amount in blood |
| Phosphorus | about 1% | Bone, cell membranes, and the molecule cells use to carry energy |
| Potassium, sulfur, sodium, chlorine, magnesium | about 1% between them | Fluid balance, nerve signalling, protein shape |
| Everything else | traces | Iron, zinc, copper, iodine, selenium, manganese, chromium |
Diagram to come
A single horizontal bar representing one hundred per cent of body mass, divided proportionally left to right: oxygen the largest block, then carbon, hydrogen, nitrogen, then a visibly narrow calcium and phosphorus, then one thin final segment for everything else. The first four blocks are tinted as one group with a bracket above them reading 96%. Proportions must be drawn accurately — the shock of the drawing is how little room the minerals occupy.
A stack of firewood is made of the same four elements in roughly the same order, and so is a loaf of bread. If composition were the story, those things would be interchangeable. The arrangement is the point: the same carbon atom is soot in one arrangement and part of a working enzyme in another.
Oxygen leads the table above for reasons that have nothing to do with importance: an oxygen atom weighs sixteen times what a hydrogen atom weighs, and a body is roughly sixty per cent water by mass. Count atoms instead of weighing them and the order reverses. Around sixty-two per cent of all the atoms in a body are hydrogen, about twenty-four per cent oxygen, about twelve per cent carbon. Both answers are correct, and both appear on the shelf: a supplement label giving a mineral in milligrams is talking about mass, while a formula such as C10H18O is counting atoms and says nothing about weight.
Of the ninety-odd elements that occur in nature, an essential oil uses three. Carbon, hydrogen and oxygen. That is the whole palette.
This is not a simplification made for a beginner and corrected later. Open a constituent report on any oil in the range and read down the compound column — limonene, linalool, linalyl acetate, menthol, eugenol, carvacrol, terpinen-4-ol, 1,8-cineole, beta-caryophyllene — and every entry is carbon, hydrogen and oxygen arranged one way or another.
| Constituent | Formula | Where you meet it |
|---|---|---|
| Limonene | C10H16 | 60–75% of Lemon; 80–97% of Wild Orange |
| Beta-caryophyllene | C15H24 | 45–65% of Copaiba |
| Linalool | C10H18O | 20–47% of Lavender |
| Linalyl acetate | C12H20O2 | 25–45% of Lavender |
| Menthol | C10H20O | 30–50% of Peppermint |
| Eugenol | C10H12O2 | 70–90% of Clove |
| Carvacrol | C10H14O | A dominant constituent of Oregano |
The sentence to sit with
Three elements. Everything this course will teach you about terpenes, alcohols, esters, phenols and oxides — every family on the chemistry wheel, every functional group, every constituent name on every report you will ever read — is carbon, hydrogen and oxygen, arranged differently. There is no fourth thing waiting later on.
Carbon alone is roughly seventy to eighty per cent of the mass of a typical essential oil, and more in the hydrocarbon-heavy citrus oils. Hydrogen fills in around it. Oxygen is the rarest of the three and the most consequential: adding one oxygen atom to a hydrocarbon skeleton is what creates a functional group. Two of the three build the frame; the third changes what the frame does.
How narrow the palette is becomes obvious when the same three counts give completely different substances. Linalool, terpinen-4-ol, 1,8-cineole and menthone all have the formula C10H18O — identical in every element and every number. Linalool is the soft floral note in Lavender, terpinen-4-ol the principal constituent of Tea Tree, 1,8-cineole the sharp eucalyptus note, menthone peppermint’s harder edge. Four aromas you could tell apart blindfolded, out of one set of numbers. The arrangement is the compound.
Diagram to come
Four skeletal structures side by side at the same scale — linalool, terpinen-4-ol, 1,8-cineole and menthone — each with the formula C10H18O printed identically beneath it. Carbon in one colour, oxygen in a second, hydrogens implied as in standard skeletal notation with a small key saying so. The reader must see at a glance that four unmistakably different shapes carry unmistakably the same formula.
Nitrogen and sulfur turn up in the volatile fraction of a few plants — the sulfur chemistry of crushed garlic is the obvious case. Across the oils you are likely to hold they are traces or nothing at all.
Look back at the body table and the overlap is hard to miss. Carbon, hydrogen, oxygen and nitrogen build the proteins, fats and carbohydrates you are made of; carbon, hydrogen and oxygen build the constituents of an oil. Nothing in a bottle is made of anything a body is not already made of. That does not tell you what any constituent does — composition is not activity, and much of what follows in this course exists to keep those two apart. It tells you the question is a chemistry question, answerable by structure rather than by argument.
Carbon is nowhere near the most abundant element on earth, and all of this is built from it anyway. There are three reasons, all of them structural. The first is that carbon forms four bonds, which is the maximum useful number. An element that forms one bond can only ever be an end. An element that forms two can build a chain and nothing else. Four lets a molecule branch, close itself into a ring, and carry a different group on each side of the same atom — which is how limonene’s ring and linalool’s open chain are both possible from the same ten carbons.
The second is catenation: carbon bonds strongly to carbon. Breaking a carbon–carbon bond takes roughly 347 kilojoules per mole, so a chain of them holds together comfortably at the temperatures a plant, a still or a body works at. Few elements bond to themselves that well, and those that do not cannot build anything long enough to be interesting. The third reason follows from the first two: tens of millions of carbon compounds have been described, and every other element put together does not come close. A terpene is ten carbons, a sesquiterpene fifteen, both assembled from the same five-carbon building block in different arrangements — one trick that generates most of the aromatic chemistry there is.
Silicon is the instructive comparison. It sits directly beneath carbon, forms four bonds too, and is far more abundant in the earth’s crust — and it builds nothing alive. Its bond to itself is much weaker, around 222 kilojoules per mole, so silicon chains fall apart rather than accumulate, and it binds oxygen so tightly that it ends up locked into the silicates that make up sand, quartz and most rock. Silicon makes the ground. Carbon makes what grows in it.
Turn away from the oils and look at the supplements on the same shelf, because a whole category of nutrient on those labels is not a molecule at all.
A vitamin is a molecule. Vitamin C is C6H8O6, and no other arrangement of those atoms is vitamin C. Because a vitamin is a molecule it can be built, and what can be built can be broken: heat, light, oxygen and time all take vitamins apart. That is why a supplement carries an expiry date, and why long boiling costs a vegetable part of its vitamin C.
A mineral is an element. Calcium is calcium. There is no arrangement to get right, nothing to assemble, and — the part that surprises people — nothing to destroy. Burn a food to ash and what stays in the dish is very nearly its mineral content; the vitamins left as smoke and water vapour, and the elements stayed behind because nothing chemical can touch them.
Supplied, never made
A body builds an extraordinary number of molecules from raw material. It cannot build an element. Every atom of calcium in your bones, every atom of iron in your blood and every atom of iodine reaching your thyroid arrived from outside — out of rock, into soil, into a plant or an animal, onto a plate. A mineral cannot be manufactured and cannot be destroyed. It can only be supplied.
The nutrient library holds thirteen minerals — calcium, magnesium, zinc, iron, iodine, selenium, copper, manganese, chromium, molybdenum, potassium, phosphorus and boron — alongside thirteen vitamins, and the line between those two groups is exactly the line this lesson has been drawing. One column is elements; the other is molecules. Which of them a body needs, and roughly how much, is what the body needs.
It also explains where minerals come from. A plant cannot manufacture an element either — it takes up what is dissolved around its roots, and that came out of the rock the soil was made from. The mineral content of a food is downstream of the ground it grew in. Within doTERRA’s range the broadest mineral content sits in Microplex VMz, though which products are available differs from country to country.
An element that reactive is never handed to you bare — elemental magnesium is a metal that burns, and elemental calcium reacts with water. What goes into a capsule is always a compound: the mineral bonded to something else, a citrate or a glycinate or an oxide. That partner is not filler. It decides how readily the compound dissolves and how much of the element is taken up, and it adds weight of its own. Magnesium oxide is only around sixty per cent magnesium by mass; the rest of what you swallow is the oxygen it came bonded to.
Which is why a good label states the elemental amount — the milligrams of the element itself, not of the whole compound. Five hundred milligrams of magnesium oxide is not five hundred milligrams of magnesium, and a label that does not make the distinction is not telling you what you have bought. Reading a supplement label takes that apart line by line.
Keep oils away from eyes and inner ears, and out of reach of children. If you are pregnant, nursing, under medical care or taking medication, speak to your healthcare practitioner before use. Nothing here is intended to diagnose, treat, cure or prevent any disease.
Three words get used interchangeably in conversation and mean three separate things in chemistry. Getting them apart once makes every later lesson easier to read.
| Kind | What it is | Examples |
|---|---|---|
| Element | One kind of atom. Nothing chemical takes it apart. | Oxygen. Carbon. Sodium. Iron. |
| Compound | Two or more elements bonded in a fixed ratio, with properties of its own that belong to neither parent. | Water. Table salt. Limonene. |
| Mixture | Two or more substances sharing a space without bonding. The proportions can be anything. | Air. Sea water. An essential oil. |
Oxygen alone does not burn, though nothing burns without it; hydrogen alone burns fiercely. Bond two hydrogens to one oxygen and you have water, which puts fires out — at a fixed ratio, two to one, never three. Carbon the element is soot, graphite and diamond, with no smell whatsoever. Take ten carbon atoms and sixteen hydrogens, close them into a ring with a short tail, and you have limonene, which smells so unmistakably of peel that it is most of what you recognise when you open Lemon.
Salt is the starkest demonstration. Sodium is a soft silver metal stored under oil because it reacts with the moisture in ordinary air. Chlorine is a heavy green-yellow gas. Combine them, one atom to one atom, and you get a hard white crystal that is stable, edible and on every table in the world — not a compromise between the two, but a third thing with no meaningful relation to either.
Diagram to come
Three panels in a row with a plus and an arrow between them. Left: a lump of sodium metal under oil, dull silver, noted as reacting with air. Centre: chlorine as a green-yellow gas in a sealed flask. Right: a single cubic salt crystal, white and ordinary, drawn at the scale of something on a kitchen table. The visual argument is that the third panel looks as though it has nothing to do with the first two.
That is the rule which makes the rest of this course readable. The properties of a compound are not those of its elements averaged together — they are new. Knowing a constituent is carbon, hydrogen and oxygen tells you nothing about how it smells, how fast it evaporates or how it behaves on skin. Only the arrangement does.
An essential oil is none of the three in isolation. It is a mixture, of compounds, built from elements. Lemon oil is not a compound called lemon; it is limonene at sixty to seventy-five per cent sitting with a hundred or more others, in proportions that shift with the harvest. That is why a constituent profile gives a range rather than a number, and why the range is a sign of honesty.
You have the units now. An element is one kind of atom — which leaves the obvious question standing in front of you. What is an atom, and why does a carbon atom form four bonds while an oxygen atom forms two? Those numbers were assumed throughout and never justified.
That is the next rung. Once you know what is inside an atom, the bonding rules stop being arbitrary facts and become consequences you can work out for yourself.
Where to go from here
Lesson 2 of 18 · Science