This song covers the four states of matter—solid, liquid, gas and plasma—and the characteristics of each one. How does matter change states? What is the difference between smoke and steam? We also take you through the laws of motion and measurements like volume and weight in this “states of matter” hip-hop song.
In 1789, Antoine Lavoisier discovered the law of conservation of mass, which states that matter cannot be created or destroyed but only changed into different forms. Then in 1842, Julius Robert Mayer discovered the law of conservation of energy, which states that energy can neither be created nor destroyed. So what do these two laws have to do with each other? No one knew until an unknown German patent office worker named Albert Einstein published a paper in a scientific journal 63 years later.
In 1905, Einstein wrote the most famous equation in history: E = MC2. What does it mean? E (for energy) equals M (for mass) times C2, the speed of light squared. Mass is the amount of matter something is made of, and the speed of light is 186,000 miles per second. The equation predicted the power of an atomic explosion, explaining how much energy is released if just one atom of matter is split. It also showed that there is a relationship between energy and matter. It took 40 years to prove Einstein's theory but in 1945 the first atomic explosion took place in Alamogordo, New Mexico. How does an atomic explosion work? E = MC2 of energy is released by splitting apart atoms of matter. But what is matter? And what are the different forms it can be changed into?
Matter is a substance that has volume and mass. Volume means that it takes up space. Mass is the amount of matter something is made of. Mass is measured in kilograms, grams, or milligrams, and comes in three basic states: solid, liquid, and gas. A fourth state, plasma, only occurs under very special circumstances.
All substances are made of matter, and matter itself is made up of particles, including single atoms and/or molecules. Because different atoms have varying numbers of protons and neutrons in their nucleus, the matter of different substances contains different masses.
Mass and volume are two of the physical properties of matter. There are other physical properties, or characteristics, of matter that we can observe as well, and use to identify a substance. For example, there's color, odor, conductivity, density, phase, boiling point, and solubility. The unique properties of different substances make them useful for different things, whether it be building a desk, conducting electricity, making toys, or human consumption (eating and drinking). This is why you wouldn't use a brick to write a letter, or a pencil to build a house - it just wouldn't work.
Color is a quality of the light waves reflected by a substance. When light waves hit a substance, they are absorbed, reflected, or transmitted. Our eyes see different wavelengths of light as different colors. What we call the color of an object is determined by the wavelength of the light waves, which the object reflects.
Odor is a quality of a substance that we can smell, caused by molecules of a substance that evaporate into the air. Not all substances have a smell or odor that we can detect. Animals like dogs and cats have a much stronger sense of smell and can detect odors humans can't.
Electrical conductivity is the ability of a substance to transmit electricity. A conductor is a substance that is good at conducting electricity, while an insulator is something that is poor at it. Copper and gold are good conductors rubber and plastic are not. That is why wires are often made of copper and insulated with plastic. Heat may also be conducted by a substance; this ability is called thermal conductivity.
Density is the amount of matter a substance has in a given amount of space. Mathematically, it's measured by the equation density equals mass over volume (D = M/V). Density is a useful measure because it isn't affected by pressure or temperature. If two objects have equal volume, but one has more mass, the one with more mass is denser. When two liquids have different densities, the lighter liquid will float on top of the denser liquid. This is called buoyancy. If a solid has less density than a liquid, it too will float; if it's denser, it will sink. Iron is denser than water, so an iron anchor thrown off a ship will sink to the bottom. Styrofoam is less dense than water, so a Styrofoam buoy will float.
Phase is the state of matter at a given temperature and pressure. There are four possible phases for most substances: solid, liquid, gaseous, and plasma. Phase is caused by the force of the attraction between a substance's particles (all substances are composed of molecules and atoms that are actually moving at all times). This force has a greater effect at lower temperatures and pressure; at higher temperatures or pressure, other forces overcome the attraction's force. The phase of a substance changes when a certain amount of energy and/or pressure is applied to it. Take liquid water, for example. In its solid phase, when temperatures are lowered to freezing, water becomes ice; in its gaseous state, it's water vapor.
The amount of solute dissolved in a solution is called its concentration. The maximum amount of solute that can dissolve in a solvent at a given temperature is its solubility. Solubility generally rises as temperatures rise, and falls as temperatures fall. The speed at which a solute can be dissolved can be sped up by mixing it, heating it, or by using smaller particles of solute. If you drop a chunk of salt in a glass of water, it will take a while to dissolve. But if you sprinkle small grains of salt from a saltshaker, or if you stir or heat the water, the salt will dissolve faster.
A solid is a substance that has a definite shape and volume. The volume of a solid object is measured in cubic units. Cubic means it has three dimensions (height, length, and depth). The volume of a solid object is measured with a formula of length times width times depth. (L x W x D = V).
So we now know that all matter has volume and mass. Volume is the size of something in space, and mass is the amount of "stuff" in that shape. But to really understand mass, you gotta understand gravity. Gravity is a force of attraction between two objects. An object's gravitational force is that object's strength in attracting other objects.
Gravitational force depends on mass and distance. Objects with a larger mass have a greater gravitational force. Stars or planets, for example, exert a stronger gravitational force than a ping-pong ball or a marble. The closer together two objects are, the greater their gravitational force. Because the Earth is huge and near to you, the gravitational force is strong. That is why you can only jump into the air for a second or less. But if you were 100 miles away in space, the gravitational force of the Earth upon you would be much weaker. You'd be able to float for a long time - probably years - before gravity forced you back to Earth.
Weight is a measure of the gravitational force exerted on an object. We usually measure the weight of an object on the surface of the Earth. But you could take your weight anywhere, and it would vary depending on what you were near. Your weight would be much greater on the sun because of its huge mass, but much less if you were on the moon or floating in outer space. In America, we usually measure weight in pounds. In science, we measure weight in newtons. To make measuring easier, scientists decided that one newton would be very close to 100 grams of mass on Earth. This means that if you know the weight of an object on Earth, you can tell its mass as well: 500 grams of mass would equal 5 newtons on Earth. Likewise, 2 newtons would equal 200 grams on Earth.
Newtons are named after Sir Isaac Newton, who discovered gravity and what we call the Laws of Motion. Part of the first law says that an object at rest remains at rest unless acted upon by another force, which simply means that an object doesn't move unless something else acts to move it. We call this tendency to resist a change in motion inertia. Mass is a way to measure inertia because an object with a larger mass is harder to move than an object with a smaller mass. Objects with a lot of mass have a lot of inertia; objects with little mass have little inertia. That is why it is easier to move a ping-pong ball than a bowling ball. You dig?
There are two kinds of solids: crystalline and amorphous. In crystalline solids, such as ice and diamonds, the atoms and molecules are arranged in repeating three-dimensional patterns or rows. In amorphous solids, like rubber and plastic, there is no special order. But in both types of solids, the substance has a rigid shape. Why? In solids the atoms and molecules are close together, creating a strong attraction between them. These particles vibrate in place but do not flow or move around, so the solid object maintains its shape and volume.
A liquid is a substance that has a definite volume, but no definite shape. It takes on the shape of its container or simply spreads out upon a surface (think of a spilled glass of milk). The volume of a liquid is usually measured in liters or milliliters.
In a liquid state, substances can change their shape because their atoms or molecules have more energy than they do in a solid state. This means that these particles are moving fast enough to overcome some of the force of attraction between them, thus allowing the liquid to flow and take the shape of whatever container you put it into.
Substances can change their phase by adding or subtracting heat energy or pressure. Vaporization (a.k.a. evaporation) is the change of state from liquid to gas. This happens when a liquid is heated to its boiling point. The less pressure there is on a liquid, the lower the boiling point. So water boils at 212°F (100°C) at sea level, but on top of a mile-high mountain, it boils at 203°F (95°C).
The condensation point is the temperature at which a gas can become a liquid again. It's the same temperature as the boiling point. A phase change from liquid to solid can occur when enough energy is removed, say by putting water in the freezer to make ice cubes. Freezing is the change of state from a liquid to a solid. Melting is the change back to a liquid.
Solubility, as we've learned, is the ability of a substance to dissolve, or uniformly mix, into another. The mixture that results is called a solution. It is made of two parts: the solute, which is the substance that is dissolved, and the solvent, which is the substance in which the solute is dissolved. When making hot tea, the water is the solvent, and the sugar is the solute. If a substance cannot dissolve in a given liquid, we say it is insoluble. If it can be dissolved, it is soluble.
In some cases two insoluble substances can be mixed together, creating something called a suspension. In a suspension, small particles of a solid are mixed into a liquid and are small enough to stay floating, or suspended, for a time. The smaller the particles, the longer they can stay suspended. Large suspended particles may be visible; just picture muddy water - it looks brown. A suspension of large particles may quickly settle to the bottom, as in a jar of Italian salad dressing. In these cases, the solid particles in a suspension can be separated from the liquid by using a filter, by letting the particles settle over time, or by waiting for the liquid to evaporate or boil into the air.
A gas is a substance that has no definite shape and no definite volume. When put into a closed container, gases take both the shape and volume of that container. If placed in the near-vacuum of outer space, a gas will simply expand outward, its molecules moving farther and farther apart. Gases can be measured in liters and milliliters at particular pressures.
In a gaseous state, substances can change their shape and their volume. The particles in a gas move so quickly and have so much energy that they can break away completely from each other. If a container expands, the particles of the gas within it can move farther apart and expand the volume of the gas to fit the container. An example is when helium under pressure in a gas canister is let into a balloon, where it then expands. If more pressure is added inside a container, the particles of gas move closer together and contract. This happens when you pump air into a basketball, making it feel harder and harder.
Some substances can change directly from a solid to a gaseous state. This is called sublimation.
Plasma is a special state of matter that, like gas, does not have a definite shape or volume. Under plasma's unique conditions, energy has caused the particles of the substance to break apart. Some plasma is extremely hot, such as in the center of the sun, in a bolt of lightning, or in the flames of a fire. Some forms of plasma can be created by passing an electric charge through a gas - unlike regular gas, plasma is affected by electric and magnetic fields. The glow of a fluorescent light, for instance, is created when electric current is pumped through a gas contained in a glass tube.
Like liquids, rappers flow. This has inspired many emcees to spit rhymes comparing themselves to various liquids and other semi-flowing things. Whose simile do you like best?
Mac Dre: "I flow like river water."
Erick Sermon: "I flow like Poland Spring."
Kool G. Rap: "I flow like a sailor."
Papoose: "I flow like a mineral chemically."
The Plain White Rapper: "I flow like H20."
Big Daddy Kane: "I flow like water."
Cannibal Ox: "I flow like arachnids on water spouts."
Soup: "I flow like orange juice or Tropicana."
Is all of this science making you hungry? Why not try a scientific sundae?
A) Find some ice cream. What state of matter is it in? Let some of it melt. What state is melted ice cream in?
B) Whip and dissolve some sugar into cream. What scientific term would we give to the sugar now? What about the cream?
C) Take a square or rectangle of chocolate. To determine the cubic volume of the piece of chocolate, what three dimensions should you measure?
D) Put an empty bowl on a triple beam balance. What unit would you use to measure the bowl?
A) When frozen, ice cream is a solid. If it melts, it is a liquid.
B) Sugar is a solute. The cream is the solvent.
C) To find the cubic volume of a piece of chocolate, multiply its length times its width times its depth.
D) The mass of a bowl is measured in grams or milligrams.