Most of the chemical makeup of the universe (stars / suns, etc) is hydrogen (75%), a very combustible element, and at a lower level, helium (23%) with the fusion of hydrogen into helium producing both light and heat. These two elements, incidentally, have been located in our moon's very thin atmosphere. The next five most common elements are estimated as being: Oxygen (1%), Carbon (½%), then Neon, Iron and Nitrogen (at about 0.1% each).
The air in our atmosphere in contrast — all 5140 trillion tonnes of it — is very rich with nitrogen 78% and oxygen 21%, followed by argon 0.9% and carbon dioxide 0.03%, then very small percentages of other elements that include water vapor, dust particles, pollen, plant grains and other solid particles.
Contrasted with 1½ million trillion tonnes of water (click here for its placement) and 6 billion trillion tonnes of earth.
The average adult human body is about 57% water, i.e. H2O, with its mass approximately 89% oxygen with 8 protons & 8 neutrons and 11% hydrogen 2x1 proton. This water component is much higher in babies, about 75% or so, and then it becomes less as we age. It is also normally lower in women than in men.
|Hydrogen||62%||10% with about 6% as being a part of the water content|
|Oxygen part of water||19%||51% (but normally lower in females)|
|Oxygen part of body||5%||14% (but normally higher in females)|
|Carbon||12%||18½% (this figure remains fairly stable in adults)|
|Remaining 3½% consists of (1) Calcium in teeth and bones about 1½%, (2) Phosphorus about 1%, and (3) about 15 trace elements: **Sulphur, Potassium and Sodium Chloride about 0.3% each, Magnesium about 0.1% then Iron, Iodine, Fluoride, Copper, Zinc, Chromium, Selenium, Manganese, Molybdenum, Vanadium and Cobalt.
**Sulphur compounds produced by certain bacteria in the gut make up the source of the odour associated most with waste and decay. Regarding bacteria cells, there are perhaps 30 to 50 trillion (or more) of them in our body alongside the 30 trillion (or so) human cells in the average adult. However as single celled micro organisms they have no nucleus, they have primitive DNA and RNA for duplicating themselves, and each one weighs just trillionths of a gram. Well over 90% are thought to be in our lower gut, and the odd trillion or so live in our saliva. In total they make up perhaps 1 - 3% of our total body weight. They are about 70% water, they have differing amounts of carbon nitrogen and oxygen, and small amounts of phosphorus and sulphur.
In human bones, as opposed to the rest of the body, the water content is 31%, carbon content is 36%, calcium content is 17%, phosphorus varies anywhere up to a max of 7%, and nitrogen is 4%. Numerous trace elements follow.
In human hair and nails, composed of the keratin protein, carbon content is 45%, oxygen content is 28%, nitrogen 15%, hydrogen 7%, and sulphur 5%.
Plant Life: Average oxygen percentage via water and carbohydrates is much higher at about 77%, hydrogen percentage remains steady at about 10%, while carbon percentage is accordingly lower, an average of 12%. Nitrogen percentage is about 1%, with various trace elements following.
In fruits and vegetables, the water percentage varies from, say, 74% in bananas to 96% in lettuces and cucumbers. Most vegetables have a water content above 90%.
With living trees, the wood content causes the carbon percentage to be higher, around
Earth Crust: Oxygen 46% Silicon 27% Aluminium 8% Iron 6% Calcium 5% with last 8% of the crust made up of many dozens of elements.
The solid inner core is almost entirely made of iron.
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