The pre-Socratic philosopher Empedocles_. From Thomas Stanley (1655), The History of Philosophy.

Matter (from Latin materia "substance from which something is made") is anything that has mass and volume. For example, blood, carbon fiber, clay, concrete, diamond ebony_, glass, gold, gunpowder_, iron, ivory, keratin, leather, oil, oxygen, plastic, polyester, porcelain_, rubber, salt, sand, silicon, silk, steel, stone, vinyl, water, or wood.

The study of matter is called chemistry.

Matter, like energy, can neither be created nor destroyed.


1   Substance

Matter is mostly empty space. If you took out all empty space from between and within the atoms making up each human being, the entire human race would fit into the volume of a sugar cube.

1.1   States

Matter comes in two states: solids and fluids. A solid has a fixed shape, where a fluid (liquid and gas) have no fixed shape.

1.2   Forms

Matter comes in two forms: chemical substances and mixtures. A chemical (substance) is a substance that cannot be decomposed by physical methods. Most substances are not chemical substances but are mixtures or aggregates of various compounds. Wood for instance is composed of carbon, hydrogen, oxygen, and a small amount of mineral matter. Likewise, the air is a mixture chiefly of two gases, oxygen and nitrogen. [2] Solids can be mixtures as well. For example, metal alloys_ such as steel.

1.2.1   Mixtures

Mixtures are divided into two kinds. A homogenous mixture is a mixture that has the same proportion of its components through and given sample. A heterogenous mixture has components whose proportions vary throughout the sample.

For example, salt water is a homogeneous mixture because the salt will mix evenly with the water, but sand and water are heterogeneous because the sand will settle to the bottom.


NaCL dissolving in water.

As a solid, Na+ and Cl- ions_ are arranged in a crystal lattice. When mixed with water, the ionic bonds are broken and Na+ and Cl- become free-floating ions because of intermolecular interactions. [4]

A solution (from Latin solutio "a loosening or unfastening") is a special type of homogeneous mixture composed of two or more substances. The substance present in the greatest amount is called the solvent and the other substances are called solutes. [4] A table of examples is listed below:

Solvent phase Solute phase Example
Solid Solid Alloy_
Solid Liquid Mercury amalgam
Solid Gas ?
Liquid Solid Salt water
Liquid Liquid Spirit
Liquid Gas Carbonated water
Gas Solid Smog
Gas Liquid Humid air
Gas Gas Air

Solutions are stable. The solute will not settle out after any period of time, and it cannot be removed by a filter or by centrifuge.

Solvents can also be thought of substances that dissolve solutes. For example, acetone dissolves nail polish.

Properties of solutions:

The number of moles of solute per liter of solution. Molarity is reported as \(M\) (read molar). Molarity depends on temperature, as density of a solution typically changes with temperature. [4]
The number of moles of solute per kilogram of solvent. Denoted by \(m\) ("molal"). [4]
Mole fraction
The number of moles of either solute or solvent divided by the total number of moles (solutes + solvent). [4]

The concentration of a solution can be measured by titration. Titration refers to adding a reagent to a solution until we observe something that tells us that exactly equivalent number of moles of the reagents are present. Titrations depend on a class of compounds known as indicators. For example, the endpoint of an acid-base titration is the point at which the indicator turns color. [5]

Type of solutions:

  • An aqeuous solution is a solution where one of the solvents is water.
  • Solutions can be divided into molecular solutions and ionic solutions. In a ionic solutions, for example salt water, ionic bonds of the solute and broken down within the compound. In molecular solutions, such as sugar water, the ionic bonds are not broken down. [4]

1.3   Enantiomers

Enantiomers are molecules that are mirror images of one another; they are structurally identical, but of the opposite orientation.

2   Composition

A molecule is the smallest particle of any pure substance which can exist without that substance changing its physical properties. Thus, water is made up of millions of water molecules, each of which is identical to the other. [2]

When chemical elements combined to form more complex substances from simple ones the process is called combination. The reverse process of breaking more complex substances down to form simpler ones is called decomposition. [2]

2.1   Chemical compound

A chemical compound is a substance of definite chemical composition, which is composed of two or more elements. In 1945, over 750,000 different chemical compounds were known. Examples of chemical compounds are water (oxygen and hydrogen), salt (sodium and chlorine), and sugar (carbon, hydrogen, and oxygen). [2]

2.2   Chemical elements

A chemical element is a substance that cannot be decomposed into simpler substance by ordinary chemical processes. There 118 known chemical elements. For example, hydrogen, helium, lithium_, boron_, carbon, nitrogen, oxygen, fluorine_, neon_, sodium, magnesium_, aluminum, silicon, phosphorous_, sulfur_, chlorine, argon_, potassium_, calcium, titanium, chromium_, iron, cobalt_, nickel_, copper, zinc, arsenic_, selenium, molybdenum_, silver_, tin_, iodine_, platinum_, gold, mercury, lead, and uranium_. About 1/5 do not exist in nature and are only known because they have been synthetically preapred in a laboratory.

The IUPAC has strict criteria for what can be considered an "element". One of this criteria is that it has at least one isotope with a lifetime at least on the order of 10-14 seconds.

As you go up in Z around the superheavy elements, they become very unstable to alpha decay and spontaneous fission. If you extrapolate the lifetimes to heavier species based on trends in nuclei that we know of, eventually you'll probably reach a point where no heavier species has a lifetime which meets that criterion in the definition of an element.

2.2.1   Aluminum


Top of a Coke can cut in half.

2.2.2   Hydrogen

Hydrogen is ... Hydrogen was discovered by Henry Cavendish, which he called "inflammable air".

2.2.3   Helium

Helium is the that was not discovered on Earth. It was found when analyzing the sun's spectrum, hence it's name which comes from the Greek god of the sun Helios_.

2.2.4   Mercury

There are several different chemical forms of mercury: elemental mercury, inorganic mercury, and methylmercury. The form of mercury associated with dental amalgam is elemental mercury, which releases mercury vapor. The form of mercury found in fish is methylmercury, a type of organic mercury. Mercury vapor is mainly absorbed by the lungs. Methylmercury is mainly absorbed through the digestive tract. The body processes these forms of mercury differently and has different levels of tolerance for mercury vapor and methylmercury.

2.2.5   Nitrogen

Liquid nitrogen added to gasoline.

In 1798, Humphrey Davy tested on himself the effects of inhaling nitrous oxide gas. He noticed two things: the euphoric effect, which led him to call it laugh gas, and the fact that it alleiate the pain of his toothache.

2.2.6   Chlorine

Added to shower and tap water. People claims it has an effect on hair and skin, but this is neutralized by Vitamin C.

When used at specified levels for water disinfection, the reaction of chlorine with water is not a major concern for human health. Other materials present in the water may generate disinfection by-products that are associated with negative effects on human health,[68][69] however, the health risk is far lower than drinking undisinfected water.

2.2.7   Calcium

Calcium is a chemical element with atomic number 20.

2.2.8   Gallium

Drop of gallium.

Gallium is a chemical element with symbol Ga and atomic number 31.

2.2.9   Iron

Iron is a chemical element. 98% of the world's mined iron ore is used to make steel.

2.2.10   Titanium


Anodized titanium.

Anodizing titanium.

Titanium is a metal.

The reason why titanium is used to replace bones is not its strength (though it certainly doesn't hurt). It's because titanium is the most biocompatible metal and has a capacity for osseointegration_, meaning the bone around it will fuse with the titanium.

This is called anodizing titanium. The current passed through it creates heat, which oxidizes (rusts) a thin, even layer on the surface.

The more the potential of the electricity, the more the heat, and the thicker the layer. The oxide layer is transparent. Light hits both the front and the back of this transparent layer, creating a color, similar to what you’d see in a soap bubble. Different thicknesses in the oxide layer correspond to different wavelengths, and so they result in different colors.

3   Substance

Matter consists of chemical elements which in turn consist of atoms.

3.1   Atom

An atom is ... Atoms consist of a nucleus and one more electrons that orbit the nucleus. The nucleus consists of protons_ and neutrons_.

3.2   Phases

Matter occurs in three principal physical states: solids, liquid, and gases. Example of solids are rocks, wood, and ice. Example of liquids are water, gasoline, and alcohol. Examples of gases are air, illuminating gas, and steam.

Matter can be changed from one physical state to another by the application of heat or pressure_.

3.2.1   Solid

A rigid body is an idealization of a solid body in which deformation is neglected. In other words, the distance between any two given points of a rigid body remains constant in time regardless of external forces exerted on it.

3.3   Fluids

Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure. The principle is named after Daniel Bernoulli, who published it in his book Hydrodynamica in 1738.

The principle can be easily demonstrated by taking a piece of paper and pulling it over the edge of a desk to give it a curve, and then blowing above it. The curved end will go up rather than down. [3]

Bernoulli's principle enabled ships to sail into the wind. By designing sails that allow air to pass more quickly on one side than the other and tiling them slightly toward the wind (parallel to the length of the ship), they could generate force toward the wind. The boat will go sidewards without a keel or centerboard, a wood or steel plate parallel to the length of the ship which is mounted directly underneath the ship, it will limit lateral motion. There is still lateral motion however, and ships will have to zig zag. It's called "tacking". Though not as efficient as sailing with the wind, it still gets you where you want to go. [3]

4   Classification

Matter that consists of atoms which have the same number of protons (atomic number) is called an element otherwise it is called a compound.

5   Properties

All matter has mass and volume by definition. Properties of matter are called material properties.

Some material properties include:

5.1   Moles


One mole of water.

The mole is a measurement of the number of atoms in a substance.

5.2   Temperature

Temperature is the measure of the average `kinetic energy`_ of the particles in a system. Temperature can be measured in Celsius_, Fahrenheit_, or Kelvin_.

  • In the Celsius scale, the freezing point of water is defined at 0 degrees and the boiling point is defined as 100 degrees
  • In the Fahrenheit scale, water freezes are 32 degrees and boils at 212 degrees (a 180 degree difference)
  • In the Kelvin scale, the coldest temperature possible is 0 degrees (-273 degrees Celsius), so there are no negative measurements. The Kelvin scale is simply the Celsius scale shifted 273 degrees.

A thermometer is a device that measures the temperature of an object.

Do atoms have temperature? Electrons?

Matter produces higher energy does light as it gets hotter (it doesn't change color). At low temperatures, they emit infrared light you can't see you that your can skin can feel, e.g. when you hold your hand up next to a heater. (This also explains how heat vision works.) When matter gets hot enough, it can give off light you can see, e.g. a light bulb filament or molten metal. As things get hotter, the color goes down the rainbow, past red, then yellow, then blue, and beyond. Matter does not be not to solid or liquid to give off light; fire is gas heated to a temperature that it emits visible light.

5.2.1   Boiling point, melting point, and freezing point


A phase diagram.


Phase diagram for CO2.

Notice that at standard atmsopheric pressure (1 atm), CO2 sublimes.

Every material has specific temperature at which it changes state.

5.3   Strength

The strength of a material is its ability to withstand an applied load without failure.

6   History

Thales thought everything was made of water; Anaximenes_ thought air was the primitive element; Heraclitus preferred fire. At last Empedocles_ suggested a statesmanlike compromise by allowing four elements, earth, air, fire and water. The chemistry of the ancients stopped dead at this point. No further progress was made in this science until the Mohammedan alchemists embarked upon their search for the philosopher's stone, the elixir of life, and a method of transmuting base metals into gold. [1]

6.1   Alchemy

Alchemy was the pursuit of turning base metals into gold. This happens in nature, and is possibly artificially using nuclear fission or a particular accelerator.

Issac Newton wrote more about alchemy than physics.

6.2   Periodic table

In 1945, there were only 92 known chemical elements. [2]

6.3   Mendeleev


Handwritten draft of the first Periodic Table.

The Russian chemist Dmitri Mendeleev published the first widely recognized periodic table in 1869. Mendeleev also predicted some properties of then-unknown elements that would be expected to fill gaps in this table. Most of his predictions were proved correct when the elements in question were subsequently discovered.

In 1869, Russian chemist Dmitry Mendeleev published his first version of the periodic table of the elements. In his final version of the table (1871) he left gaps, foretelling that they would be filled by elements not then known and predicting the properties of those elements.

Russian chemist Dimitri Mendeleev 150 years ago. He discovered that elements exhibit similar properties at regular intervals when arranged in order of their atomic weights.

6.4   Nobel

Italian chemist Ascanio Sobrero discovered nitroglycerin in 1847 by adding glycerine slowly to a mixture of nitric and sulphuric acids. When he discovered the explosive power of a single drop, he named the new compound "pyroglycerin". Sobrero was horrified by his discovery, and made not effort to develop its power.

In 1867, Alfred Nobel discovered by accident that nitroglycerin was absorbed to dryness by diatomaceous earth or kieselguhr, a porous siliceous earth, and the resulting mixture was safer to use than nitroglycerin alone.

6.5   Atomic theory

There have been multiple atomic models including the Rutherford model, the Bohr model, the Dalton model, and the quantum model.

Nicolau Saker Neto. 2018-11-25. Why do we call O2 oxygen?

I think what you may find most helpful is to know a bit of the history of element discovery and atomic theory.

The first pure substance containing only the element oxygen to be isolated was dioxygen (O2), in 1774, though it was called "dephlogisticated air" until 1777 when Lavoisier used the term "oxygen" for the first time. This was some 30 years before John Dalton even proposed the first empirical atomic theory. Back then, we only barely had an understanding of stoichiometry, such that Dalton famously claimed the molecular formula for water was HO. The fact that dioxygen is a substance made of molecules containing two atoms of oxygen probably wasn't widespread knowledge until at least 1811, with the gas stoichiometry experiments of Amadeo Avogadro.

Basically, for a point in time, we knew that there was a substance composed of a single type of atom, which could not be broken down into anything simpler. This fit the then-prevalent definition of an element; "a pure substance that could not be decomposed into any simpler substance". We knew that Lavoisier's "oxygen" had to be On, for some n, but we had no reason to assume n≠1 for decades. By the time we figured out n=2, the name "oxygen" was already widely used to refer to dioxygen. The fact that n=3 also forms a stable compound in ambient conditions (ozone) would also not be known until 1867. A similar story happened with (di)nitrogen (octa)sulfur,

(tetra)phosphorus, and so on. The only elements which form stable monoatomic substances in reasonable conditions are the noble gasses.

There is an interesting aspect to consider behind all this. There are some (such as Eric Scerri) who claim we are doing Chemistry a disservice in muddling together the properties of elements and the pure substances which they make. Nowadays our definition of an element is solely dependent on the number of protons inside an atomic nucleus, with no reference to reactivity or in what form the pure substance can be found. In this sense, the elements do not have "reactivities", "melting points", etc.; these are all properties of the pure substances. The only true properties of the elements are things such as electronic distribution, ionisation energies, and so on. However, it is common to see periodic tables stating the melting and boiling points the pure substances of each chemical element, and even Wikipedia bundles the physical properties of dioxygen with the atomic properties of elemental oxygen. For better or for worse, we're stuck with this subtle ambiguity in nomenclature.

7   Market

The most (by what?) consumed materials in the world are water, cement_, and sand. (Water and sand are both ingredients of cement_.)

8   Study

Chemists spend a lot of time in labs because to go from reactants to a product involves mixing the chemicals together to form the product and byproducts, and then purifying the mixture to get just the product. Since chemicals can combine between steps, chemists usually must complete the process all in one go. (Though sometimes they can freeze the mixtures to prevent a reaction.)

9   Further reading

10   Questions

11   References

[1]Bertrand Russel. 1945. The History of Western Philosophy. 58-
[2](1, 2, 3, 4, 5) Technocracy Inc. 1945. Technocracy Study Course. Lesson 1: Matter.
[3](1, 2) Rob Morrison. The Curiosity Show.
[4](1, 2, 3, 4, 5, 6) Washington University in St. Louis. 2005.

Dr. Schambaugh is known for asking questions such as, "why do airplanes fly?" on his final exams. His one and only final exam question in May 1997 for his Momentum, Heat and Mass Transfer II class was: "Is hell exothermic or endothermic? Support your answer with proof."