A Brief Introduction To Water

Water is a contradiction. A molecule of water is made of hydrogen, which is extremely flammable, and oxygen, which although it does not burn by itself, is a great facilitator if fire. Oxygen makes fires burn brighter, and without oxygen, a fire will not burn. Yet, when these atoms are combined into a water molecule with two hydrogen atoms and one oxygen atom, the result is dihydrogen monoxide, better known as water, which not only will not burn but is used to put out fires. How does this happen?

Let’s start with a dew drop on a blade of grass. Dew happens when the humidity level in the air at a particular location becomes so high that the air is saturated and cannot hold any more moisture. The heavy molecules of water then condense on the ground and cover plants, lawn furniture, and whatever else is down there. The temperature at which the moisture molecules begin to condense and form dew is called the dew point. Since the air is usually cooler at night and the moisture content of the air is higher because it is not being evaporated by the sun in the middle of the day, condensation usually occurs at night. On a sunny morning dew will usually evaporate in about an hour.

A tiny drop of condensed moisture on a blade of grass will be about .003175 meters or about 1/8^th of an inch in diameter. This is small, but then we get into the quantum world where things get really tiny. The dew drop is made of millions of water molecules each of which is roughly .000282 millionth of a meter wide and made of two hydrogen atoms and one atom of oxygen connected in what is called a hydrogen bond. Each hydrogen atom contains one proton and one electron in an orbital around it and the atom is about 2.5 X 10 to the minus 11 meters in diameter. The more crowded oxygen atom contains eight protons and eight electrons, as well as 8 neutrons and at 7.4 X 10 to the minus 11, is somewhat heavier and bigger than the hydrogen atom.

The bonds between the hydrogen and oxygen atoms happen when the single negatively charged electron in of each of two hydrogen atoms are attracted by the eight positively charged protons of the oxygen atom. The outer shell of the oxygen atom, the valence shell, has six electrons and needs two more to make it conform to the octet rule and become a completely stable atom with eight electrons in its valence shell. It gets these needed electrons from the two hydrogen atoms.

Looking deeper into the subatomic level of the dew drop, we get to its fundamental components that are even smaller than the atoms of hydrogen and oxygen, that is, we get to its quarks and gluons which are the basic constituents in the protons and neutrons of every atom. Quarks, by the way, were discovered by physicists Murry Gell-Mann and George Zweig in 1964 and named by Gell-Mann after a passage in James Joyce’s book Finnigan’s Wake that reads “Three quarks for Muster Mark…”, a word that supposedly was intended to sound like the squawk of a seagull.

Quarks have partial electrical charges based on the amount of charge of an electron. An ‘up quark’ has a 2/3 electron charge, while a ‘down quark’ has a 1/3 electron charge. Each proton and neutron contain three quarks: two ‘up quarks’ and one ‘down quark’ in the proton giving it a positive charge, and two ‘down quarks’ and one ‘up quark’ in the neutron gives it a neutral charge. Quarks are held together by particles appropriately called gluons in a complicated sub-atomic process that physicists call quantum chromo dynamics or QCD.

Estimated to be around 10 to the minus 15 millimeters in diameter, quarks are believed to be fundamental, that is, they cannot be broken down into smaller particles. They do have a small amount of mass, however. The other fundamental particles that have mass that are also particles found in atoms are tiny electrons which are even smaller than quarks. And since quarks and electrons make up all of the atoms, it is these two extremely small particles that make up all the matter we see in the universe: galaxies, stars, Earth, and us. Along with massless photons and nearly massless neutrinos, quarks and electrons are about as small as things get in the universe. So, we see that even a small dew drop has a complicated atomic structure.

If we look at this on a human scale, going from electrons to quarks, to protons and neutrons, to atoms, to molecules, to cells, one can see that the human body is made of many trillions of ultra-tiny particles. Thus, a human body is a profound example of numerous inorganic particles organized by time and natural selection in such a way as to achieve not only organic life, but life capable of being mindful of itself and able to contemplate its place in the vast universe. Could one go so far as to say that through the human mind quarks and electrons have become introspective?

So now we know what water is made of at the fundamental level. But how did it get to Earth, and what happened to cause two flammable substances to become nonflammable?

Most of Earth’s water was made in the universe long before the Earth was formed by clouds of cosmic particles leftover from the formation of our sun. At the beginning of the universe, the so-called big bang, which occurred some 13.8 billion years ago, large amounts of quarks and electrons were dissipated into space. For about 380,000 years the universe was too hot for these particles to join together to form larger particles. But when the temperature cooled somewhat, the positive and negative electric charges in the quarks pulled them together to form protons and neutrons.

Clouds of these particles floated around in space and in time the positively charged protons began to be attracted by the negatively charged electrons. These charged particles began to form clumps of particles that grew over time as more particles were attracted. In a few million years, the clumps became large enough that they developed gravity, the same interaction that holds us down to Earth.

As the clumps became bigger, the strong pull of gravity from the center of the clump created enormous density and heat which pushed the electrons and protons together to the point that they merged into the first atoms. The first atoms were tiny hydrogen atoms which contained one proton and one electron in an orbital around it. These atoms were so small they did not have room for a neutron.

Gravitational pressure continued to increase to the point that nuclear fusion ignited in the hot and high-pressure core of the clump of hydrogen atoms, and the first star was born. The hydrogen atoms began to fuse together into the next heaviest atom, helium, which had two protons, two electrons and was large enough to also contain two neutrons. Since the formation of that first star a few million years after the big bang, billions and billions more have followed.

Each new star started out with a finite amount of hydrogen depending on the size of the clouds of atoms that it formed from. As time passed and the fusion process or stellar nucleosynthesis continued in the cores of stars, many of them, especially the larger ones that had cores so large that they eventually burned up their hydrogen fuel in just a few million years. At that point the helium atoms themselves begin fusing together into even heavier atoms. After helium came carbon with six protons, six neutrons, and six electrons, and then about a billion years after the big bang, oxygen atoms began to be created, each with eight protons, eight neutrons, and eight electrons – two electrons in the inner shell and six in the outer or valence shell.

The process is still going throughout the universe today. Thus, stars are born when their hydrogen atoms clump tightly together and begin to fuse into heavier elements such as helium, carbon, oxygen, and many others. Then when they use up their hydrogen and helium fuel, they can take different paths according to their size. Small stars can wind up as red giants and then white dwarfs, while the largest ones can explode into supernovae, become neutron stars, or even stellar black holes with intense gravitational fields.

It is interesting to note that the star Betelgeuse in the constellation Orion is in its red giant phase. It is so huge that if placed in the location of our sun, it would reach beyond the orbit of Jupiter. It will probably explode as a supernova in the next few thousand years, but at around 724 light years from Earth, it will put on quite a light show but should not damage Earth or its inhabitants.

Once the process of stellar nucleosynthesis started it created enumerable oxygen atoms, and when the old stars burned up their fusion fuel and exploded, those oxygen atoms were spewed out into space where they mixed and mingled with the many hydrogen atoms floating around. When these clouds of gases came close to the heat of an exploding star, the hydrogen-oxygen mixture exploded causing the hydrogen and oxygen atoms to bond into enumerable billions of molecules of water. The water molecules then became attached to asteroids, comets, cosmic dust, and planets.

This process has gone on for billions of years and has made water one of the most abundant substances in the universe today. It is found on planets, asteroids, comets, and moons usually as frozen ice. On some planets, however, located near enough to a star to keep the surface of the planet above zero degrees Celsius, it can be found in liquid form. Lucky for us, Earth is a well-located planet with plenty of liquid water where life could be born and evolve.

How our trillions of gallons of water got to Earth is still the subject of some debate, and it looks as if it might have been a combination of events that brought it here. To start with, there were water molecules attached to some of the cosmic gases and debris that were left over from the formation of our sun about 5 billion years ago. When this cosmic ‘dust’ coalesced into the planets of our solar system, all the planets and most of their moons started out with some water on them.

We know, for example, that years ago Mars had large amounts of water and might still have some in its polar regions. Ganymede, a moon of Jupiter and the largest moon in the solar system, has beneath its surface an ocean of water that might contain more water than is found on Earth. Europa, another moon of Jupiter also has large amounts of water, as well as Enceladus, one of Saturn’s moons. Earth’s moon, called Selene in Greek or Luna in Latin, has some water at the poles. Thus, water was ubiquitous at the beginning of our solar system, and is still found on most of the planets and moons

So, in all likelihood Earth had water when it formed. It is believed, however, that much of Earth’s original water was lost when it collided with another smaller planet about 4.3 billion years ago, not long after Earth coalesced. Although Theia, as the smaller planet has been named, would have brought water to Earth, the heat from the collision would have caused a large percentage of Earth’s and Theia’s water to evaporate into space. So, Earth had to wait for an additional source of water.

There was a lot of debris left over from the formation of the sun, Earth and the other planets that began swirling around in our solar system as asteroids, and many of them contained molecules of water. For years these asteroids have been hitting Earth and bringing varying amounts of water with them. In the next three billion years or so after the Theia collision, thousands of asteroids and comets containing water hit Earth before the atmosphere was dense enough to burn them. In fact, the number of celestial objects hitting Earth for several years was so great that scientists have named the phenomenon the “late heavy bombardment”.

Fortunately, Earth had cooled enough that the water these asteroids and comets brought with them stayed on Earth filling the low places in Earth’s terrain and in time carving out ocean basins, rivers, lakes, canyons, and coastlines. Although we still occasionally get hit with asteroids, we humans are fortunate that the great bombardment of large water-bearing objects happened many years ago. If we had all of those asteroids and comets hitting Earth today, we would probably be wiped out.

However, there are still thousands of asteroids out there in the Asteroid Belt between Mars and Jupiter and the Kuiper Belt beyond the orbit of Neptune. Many of these objects enter our atmosphere every day, but fortunately most are very small and burn up before they reach us. But occasionally a big one is spotted burning up in Earth’s atmosphere, and every few years, one makes it all the way to the Earth’s surface.

One is reminded of the asteroid that hit Earth 66 million years ago that killed 70% of all life at the time, including the large dinosaurs. It has been estimated to have been about six miles in diameter. Ironically, although the asteroid killed a large percentage of life on Earth, by killing the predacious dinosaurs, it allowed the evolution of mammals which evolved into primates and humans. But an asteroid that large hitting Earth today would kill billions of people, so we are pleased that NASA’s Double Asteroid Redirection Test showed that it could be possible to redirect an asteroid heading toward Earth. The DART test was quite an engineering feat hitting an object 160 meters wide located in space 11 million kilometers away.

Over the next millions of years, as Earth filled up with water, a strange phenomenon occurred. It was not long, at least geologically speaking, after Earth got its oceans of water that primitive life began to form in them. Along with the water that came to Earth had come a variety of elements that had originated in exploding stars many light years away. Earth’s water became an element-rich soup.

So, perhaps it was inevitable that electrons in the atoms of carbon, hydrogen, oxygen, nitrogen, phosphorous, and sulfur floating around in Earth’s various bodies of water began to form covalent bonds with each other. Then following millions of years of haphazard combinations, these strings of atoms evolved into molecules and eventually produced amino acids that led to the creation of proteins and nucleic acids.

Thus, the presence of liquid water had become the catalyst for inorganic elements to spawn the organic molecules which form the billions of lifeforms that have lived in the past and are alive now. The rest, as they say, is biological history. Today these covalent combinations make up most of the biological molecules on Earth.

Life on Earth started with water and in water, and all living things from cells to the human body contain more water than any other substance. Once started, complex life evolved slowly but deliberately and made good use of water.

Although single-celled life first arose on Earth some 3.8 billion years ago, it was not until around 650 million years ago that muti-celled life evolved. Primitive human beings began to show up roughly 3 million years ago, and we Homo sapiens started thinking about ourselves and realized that we might be different from other animals only around 300,000 years ago. Then it was well over another 250,000 years before Homo sapiens began living in cooperative communities and showing signs of becoming civilized humans. Natural selection is a slow process but it got us to where we are today.

We owe water a great deal of gratitude. We would not have made it without water, and the human body needs water so much that it can only go three days without it until death. But for years we took it for granted. We did not know what it was made of nor where it came from. It was not until the late 1700s that scientists began to try to understand more about this ubiquitous liquid that is so essential to our existence.

Scientists Joseph Priestly in 1781 is believed to be the first to ignite hydrogen and oxygen atoms together to cause an explosion that produced water. Henry Cavendish performed the same experiment in 1783, but neither scientist understood quite how the process worked. A few years later in 1805 French chemist Joseph Gay-Lussac established that water is made of two hydrogen atoms bonded to an oxygen atom. The stuff that we knew we needed to stay alive turned out to be made of two of the most abundant and the most flammable elements in the universe. For this and other discoveries Gay-Lussac became famous and is one of 72 scientists to have his name inscribed on the Eiffel Tower in Paris.

Every one of us is made of 65% water, and all living things contain some water. Thus, water not only connects each individual with every other living thing on Earth but, as far we can tell, it also connects us to every living thing on every water-bearing planet, every moon, every asteroid, and every comet in the universe as well. In our quest to find life on other planets, the first thing we look for is water. If we find it, there could be life there.

So, why then does water which is made of combustible atoms not burn. The answer most scientists come up with is that the hydrogen and oxygen atoms have already burned. Since water is formed when hydrogen and oxygen atoms explode when they are hit with lightning or exposed to the heat from an exploding star, the atoms go through a chemical transition much like the atoms of wood go through when they burn. Trying to burn water would be the same as trying to relight the ashes of burnt wood. The ashes will not burn, and neither will the atoms making up a water molecule.

Hydrogen’s ability to burn and produce a high amount of energy is why it is used in rockets launched into space. A large amount of thrust is needed to propel a rocket beyond the gravitational pull of Earth and hydrogen provides that energy. There is also a great deal of research done on using hydrogen as a fuel source for automobiles.

Although hydrogen is one of the most abundant atoms on Earth, most of it is tied up in the form of water. Free hydrogen atoms are so light that they quickly evaporate into space. To separate the hydrogen from the oxygen in a water molecule requires a process called electrolysis, which uses electricity to cause the molecule to split apart. At the present time, this is an expensive and complicated process and researchers are working to come up with better ways to produce large amount of hydrogen.

It is interesting to note that green plants through the process of photosynthesis have been using sunlight to power the splitting of water molecules into hydrogen and oxygen for over three billion years. Unfortunately, the scale of the phenomenon in an individual plant is too small to be of any industrial use. But we are learning how to replicate the process.

We would have no history without hydrogen, oxygen, and water, and they will continue to be important to all living creatures. Rockets and cars need hydrogen to burn, humans and numerous other lifeforms need oxygen to breathe, and life would not have evolved and cannot be sustained without these two atoms bonded together into water.

Ted McCormack