The Study of MATTER!

MATTER Matter, matter everywhere. Except in a vacuum of course. Matter is everything. We've already told you that chemistry is the study of matter and how it changes and interacts with other matter. But what is matter?

MATTER IS THE STUFF AROUND YOU
Not very clear, but it's true. Anything that takes up space or has a mass of any kind is matter. Everything you can touch is made of matter. If it is made of anything, that anything is matter. Everything you will learn about Chemistry will all be based on how matter reacts and combines.

Matter has many properties. It can have PHYSICAL properties like different densities, melting points, boiling points, freezing points, color or smells. There are also CHEMICAL properties that define matter. A good example of chemical properties is the way elements combine with each other in reactions. The big thing to remember... Matter can change in two major ways, physically and chemically.  

STATES OF MATTER
There are four main STATES of matter. SOLIDS, LIQUIDS, GASES, and PLASMAS. Each of these states is also known as a PHASE. ELEMENTS and compounds can move from one phase to another phase when special physical forces are present (* physical, not chemical *). One example of those forces is TEMPERATURE. When temperature changes, the phase can change. Generally as the temperature rises, matter moves to a more active state.

Phase describes a PHYSICAL state of matter. The key word to notice is physical, because things only move from one phase to another by physical means. If energy is added (like increasing the temperature or increasing pressure) or if energy is taken away (like freezing something or decreasing pressure) those are physical changes. Those kinds of forces change states of matter.

One compound or element can move from phase to phase, but still be the same substance. You can see water vapor over a boiling pot of water. That vapor (or gas) can condense and become a drop of water. If you put that drop in the freezer, it would become a solid. No matter what phase it was in, it was always water. It always had the same chemical properties. On the other hand... A chemical change would change the way the water acted, eventually making it not water, but something completely new.

CHEMICAL FORCES DO NOT CHANGE THE STATE
Other forces that can be applied to something are the chemical forces. If you pour acid on something it dissolves. That isn't changing from one phase to another, it is changing the basic chemical structure of the compound. NOT the physical state of matter it happened to be. A simple example is when alcohol is poured on Styrofoam.

 LIQUID BASICS
By now you know what a solid is. If you wave your arms around you can find a gas. But what about liquids? Not that we suggest it but you know you've got some spit. That's a liquid. What about your blood? That's a liquid too. The main thing is to figure out what makes those things liquids.

Liquids are an in-between phase of matter. They are right between solids and gases. One characteristic of a liquid is that it fills the shape of any container. So you pour some water in a cup. It fills up the bottom of the cup first and then fills the rest. It also takes the shape of the inside of the cup. It starts filling at the bottom because of GRAVITY. When it is in that cup it also has a flat surface. That's because of gravity too.

One other characteristic of liquids is that they are very hard to COMPRESS. When you compress something you take a certain amount and force it in a smaller space. Solids are tough to compress too but gases are easy. When you compress something you squeeze it so the atoms in the substance are closer together. When pressure goes up... Substances are compressed. Liquids already have their atoms close together so it's hard to push them even closer.

SO YOU WANT TO BE A LIQUID
If you want to be a liquid you could start out as two different things. You could be a solid or you could be a gas. Each of them has a different way of becoming a liquid.

Let's say you're a solid. That's you. A handsome cube of ice sitting on a counter. All you do is dream of becoming liquid water. What you need is some ENERGY. Atoms in a liquid have more energy than the atoms in a solid. The easiest energy around is probably heat. There is a magic temperature for every substance called the MELTING POINT. When a solid reaches the temperature of its melting point... It can become a liquid. For water the temperature has to be a little over zero degrees Celsius. If you were salt, sugar or wood your melting point would be higher than water.

So solids need more energy. The reverse is true if you are a gas. You need to lose some energy from your very excited gas atoms. The easy answer is to lower the surrounding temperature. When the temperature drops, energy will be sucked out of your gas atoms. When you get to the CONDENSATION POINT, that's the temperature when you become a liquid. If you were the steam of a boiling pot of water and you hit the wall, the wall would be so cool that you would quickly become a liquid.

EVAPORATION
Sometimes a liquid can be sitting there and its molecules will become a gas. That's called EVAPORATION. You might be wondering how that can happen when the temperature is low. It turns out that all liquids can evaporate at room temperature and pressure. Evaporation is when there are atoms or molecules escaping from the liquid and turning into a vapor. You see... Not all of the molecules in a liquid actually have the same energy. The energy you can measure is really an AVERAGE of all the molecules. There are always a few molecules with a lot of energy and some with barely any energy at all. It is those with a lot of energy that build up enough power to become a gas and leave the liquid. When it leaves it has evaporated.

ATOMS
Atoms are the basis of chemistry. They are the basis for everything in the Universe. You already learned in the matter section that matter is composed of atoms. That's true. Atoms and the study of atoms are a world unto themselves. We're going to cover basics like atomic structure and bonding between atoms. As you learn more, you can move to the biochemistry section to see how atoms form compounds that make the biological world happen.

SMALLER THAN ATOMS?
You'll soon be learning that atoms are composed of pieces like Neutrons, Electrons and Protons. But guess what? There are even smaller pieces moving around in those atoms. Scientists have many names for those pieces, but you may have heard of NUCLEONS and QUARKS. Nuclear chemists and physicists work together with particle accelerators to discover the presence of these tiny, tiny, tiny pieces of matter.

Even though these super tiny pieces exist, it is still the basic organization of the atoms that make the chemistry in the Universe happen the way it does.

BONDING
So you're here to learn about bonding. First you need to learn why atoms bond together. We use a concept called "Happy Atoms." We figure most atoms want to be happy.

The idea behind happy atoms is that atomic shells like to be full. That's it. If you are an atom and you have a shell... You want your shell to be full. Some atoms have too many electrons (one or two extra). These atoms like to give up their electrons. Some atoms are really close to having a full shell. Those atoms go around looking for other atoms who want to give up an electron.

Simple, right? Let's take a look at some examples...

The first shell is filled with 2 electrons, the second is filled with 8 electrons, and the third is filled with 8 (for the first 18 elements).

As we continue you can see that sodium (Na) and magnesium (Mg) have a couple of extra electrons. They, like all atoms, want to be happy. They have two possibilities. (1) They can try to get eight electrons to fill up their third shell. Or (2) they give up a few electrons and have a filled second shell. For them it's easier to give up a few electrons.

What a coincidence! There are other atoms who are interested in getting a few extra electrons...

Just above are oxygen (O) and fluorine (F). Each is looking for a couple of electrons to make a filled shell. They have one filled shell with two electrons but their second shell wants to have eight. There are a couple of ways they can get the electrons. (1) They can share electrons, making a covalent bond. Or (2) they can just borrow them, and make an ionic bond (also called electrovalent).

So we've got a sodium (Na) atom that has an extra electron. We've also got a fluorine (F) atom that is looking for one. Sometimes this happens...

They work together and both wind up happy! Sodium (Na) gives up its extra electron. The sodium (Na) has a full second shell and the fluorine (F) has a full second shell. Two happy atoms! That's one way things are able to bond together, by giving up and sharing electrons.

COMPOUND BASICS
Compounds are groups of two or more ELEMENTS bonded together. There are two main types of bonds which hold those atoms together. There are COVALENT and IONIC/ELECTROVALENT bonds. Covalent compounds happen when the electrons are shared by the atoms and ionic compounds happen when electrons are donated from one atom to another.

We talked about compounds and molecules in the matter section. When we discuss phase changes to matter the changes are because of physical forces. When we talk about compounds, bonds are formed and broken down by chemical forces. Compounds (unless you're inside of the Sun or something extreme) cannot be broken down by physical forces. Chemical forces are forces caused by other compounds or molecules that act on substances.

There are millions of compounds everywhere you look. Chances are that everything you can see is one type of compound or another. When elements join together and become compounds they lose their individual traits. Sodium alone is very reactive. But when sodium combines with chlorine (another reactive element) they form a non-reactive substance called sodium chloride (Salt, NaCl). The compound has none of the traits or the original elements. It has a new life of its own.

DIFFERENT BONDS IN MOST COMPOUNDS
Most compounds are made up of combinations of bonds. If you look at sodium chloride (NaCl) it is held together by one ionic bond. What about magnesium chloride (MgCl)? One magnesium (Mg) and two chlorine (Cl) atoms. So that's two ionic bonds. There's a compound called methane (CH₄). It is made up of one carbon (C) and four hydrogens (H). Four bonds... All covalent. Those are very simple compounds, but most compounds are combinations of ionic and covalent bonds.

Let's look at Sodium hydroxide (Na-OH)...

You can see that on the left is the sodium (Na) part and the right has the oxygen/hydrogen (-OH) part. The bond which binds the hydrogen (H) to the oxygen (O) is covalent. The sodium (Na) is bonded to the HYDROXIDE part of the compound with an ionic bond. This is a very good example of how there can be different types of bonds within one compound.

FUSING IDEAS TOGETHER
Where can we begin? 1967 Nobel Prize. One of the chiefs of the Manhattan Project (First Atomic Bomb). Leader in fusion research and how stars make their energy. He studied Cosmic Rays when he was 90. Born in Alsace-Lorraine in 1906, he received his Ph.D. at 22. Like many other scientists, he left Europe during World War 2. He came to Cornell.

More than just a scientist, Hans Bethe has worked to make the world a better place. He worked to make sure that governments were responsible with their new atomic weapons. He worked with President Clinton, when he was 90, to create the Comprehensive Test Ban Treaty (it limits nuclear weapons testing). More than anything, he was always a great guy. When you look on the web, you will find tons of information praising Dr. Bethe for his work and his great attitude towards life.

 Now we're getting to the heart and soul of the way your universe works. Elements are the building blocks of all matter. We talked about quarks in the atoms section. Sure, they are smaller than the atoms of an element, but only when they group with other quarks do they form atoms that have recognizable traits. Some quarks combine to make an oxygen atom. Other quarks can combine to form a nitrogen atom. It's the atoms that are different and unique, even though they are made up of the same pieces.
 

ELEMENTS
THE SAME EVERYWHERE
As far as we know there are only so many basic elements. Up to this point in time we have discovered/created over 100. While there may be more out there to discover, the basic elements remain the same. Iron atoms found on Earth are identical to Iron atoms found on meteorites. The Iron atoms on Mars that make the soil red are the same too.

The point is... With the tools you learn here, you can explore and understand the Universe. You will never stop discovering new reactions and compounds, but the elements will remain the same.

THE LIST OF ELEMENTS
We've got 18 to choose from. From the launch of the site we've been asked, "Why only 18?" The rules for the first 18 elements are very straight-forward. (1) Electrons fit nicely into three shells. (2) These elements make up most of the matter in the universe. (3) It's a lot easier to remember facts about 18 elements than over 100 elements.

PERIODIC TABLE

As you probably saw, the periodic table is organized like a big grid. The ELEMENTS are placed in specific places because of the way they look and act. If you have ever looked at a grid, you know that there are ROWS (left to right) and COLUMNS (up and down). The periodic table has rows and columns too and they each mean something different.

When you look at the picture to the right you can see that the rows are different colors. Even though they skip some squares in between, all of the rows go left to right. When you look at a periodic table, each of the rows are considered to be different PERIODS (Get it? Like PERIODic table!).

In the periodic table, elements have something in common if they are in the same row. All of the elements in a period have the same number of atomic SHELLS. We talk about shells when you go look at the elements in detail.

Every element in the top row (the first period) has one shell for its electrons. All of the elements in the second row (the second period) have two shells for their electrons. It goes down the periodic table like that. At this time, the maximum number of shells is seven.

Now you know about periods. The periodic table has a special name for its columns too. When a column goes from top to bottom, it's called a GROUP. The elements in a group have the same number of electrons in their outer shell.

Every element in the first column (group one) has one electron is its outer shell. Every element on the second column (group two) has two electrons in the outer shell. As you keep counting the columns and you'll know how many electrons are in the outer shell.

You'll may notice that HYDROGEN is special. Hydrogen can have the talents and electrons of two groups, one and seven. To scientists, Hydrogen is sometimes missing an electron, and sometimes it has an extra.

HELIUM is another exception. Helium is different than all of the other elements. It can only have two electrons in its outer shell. Even though it only has 2 it is still grouped with elements that have eight.

The elements in between, with the grey color, are called TRANSITION elements. They have special electron rules.

 HYDROGEN

HY-DRO-GEN

HYDROGEN is the first (1) element in the PERIODIC TABLE. A scientist named Louis Guyton de Morveau gave it a name in 1787.

Because hydrogen is the first element in the periodic table it is very small and very light. In fact, it is the lightest of all the ELEMENTS.
BERYLLIUM

Check out the blackboard. That box on the left has all of the information you need to know about one element. It tells you the mass of one atom, how many pieces are inside and where it should be placed on the PERIODIC TABLE.

In the next section we're going to cover electron orbitals or electron shells. This may be a new topic to some of you.

ELECTRONS IN THE SHELLS
See the picture to the right? Each of those colored balls is an ELECTRON. In an atom, the electrons spin around the center, also called the NUCLEUS. The electrons like to be in separate SHELLS. Shell number one can only hold 2 electrons, shell two can hold 8, and for the first eighteen elements shell three can hold a maximum of eight electrons. As you learn about elements with more than eighteen electrons you will find that shell three can hold more than eight. Once one shell is full, the next electron that is added has to move to the next shell.

 CARBON 

SODIUM 

Let's start with the idea of a reaction. In chemistry, a reaction is when two or more molecules interact and something happens. That's it. What molecules are they? How do they interact? What happens? Those are all the possibilities in reactions. The possibilities are infinite.

KEY POINTS
(1) A chemical change must occur. You start with one compound and turn it into another. That's an example of a chemical change. A steel garbage can rusting. That rusting happens because the iron in the metal combines with oxygen in the atmosphere. A refrigerator or air conditioner cooling air is not a reaction... That is a physical change. But a chemical reaction can happen inside of the air conditioner.

(2) It could be ions, molecules or pure atoms. We said molecules in the above section, but a reaction can happen with anything, just as long as a chemical change occurs (not a physical one).

(3) Single reactions often happen as part of a larger series of reactions. Take something as simple as moving your arm. The contraction of that muscle requires sugars for energy. Those sugars need to be metabolized. You'll find that proteins need to move in a certain way to make the muscle contract. A whole series (hundreds actually) are needed to make it happen.

 ACIDS & BASES

ACIDS AND BASES ARE EVERYWHERE
Look around you and every liquid you see will probably be either an acid or a base. The only exception would be distilled water. Distilled water is just water. That's it. Most water you drink has ions in it. It is those ions which make something acidic or basic.

In your body there are small compounds called Amino Acids. Those are acids (Duhh). In fruits there is something called Citric Acid. That's an acid too (Duhh again). But what about baking soda? When you put that in water it makes a base. Vinegar? Acid.

Scientists use something called the "pH" scale to measure how acidic or basic a liquid is. The scale goes from "0" to "14". Distilled water is 7 (right in the middle). Acids are found between "0" and "7". Bases are from "7" to "14". Most of the liquids you find every day have a pH near "7", either a little below, or a little above. When you start looking at the pH of chemicals the numbers go to the extremes. If you ever go into a chemistry lab, you could find solutions with a pH of "1" and others with a pH of "14". Those chemicals are very dangerous. There are pH values higher than 14 and lower than 0, but let's just start with 0-14.

NAMES TO KNOW
Here are a couple of definitions you should know...

ACID: A solution that has an excess of H⁺ ions. It comes from the Latin word "acidus" which means "sharp".
BASE: A solution that has an excess of OH^- ions. Another word for base is ALKALI.
AQUEOUS: A solution which is mainly water. Think about the word aquarium. AQUA means water.
STRONG ACID: An acid which has a very low pH (0-4).
STRONG BASE: A base which has a very high pH (10-14).
WEAK ACID: An acid that only partially ionizes in an aqueous solution. That means not every molecule breaks apart. They usually have a pH close to 7 (3-6).
WEAK BASE: A base that only partially ionizes in an aqueous solution. That means not every molecule breaks apart. They usually have a pH close to 7 (8-10).
NEUTRAL: A solution which has a pH of 7. It is neither acidic nor basic.

WHAT REALLY HAPPENS
A little tricky here. We'll give you the straight answer...

Acids are compounds which break into hydrogen (H⁺) ions and another compound when placed in an aqueous solution. Bases are compounds which break up into Hydroxide (OH^-) ions and another compound when placed in an aqueous solution.

 If you have an IONIC compound and you put it in water it will break apart into two ions. If one of those ions is H⁺... The solution is acidic. If one of the ions is OH^-... The solution is basic. There are other ions which make acidic and basic solutions, but we won't be talking about them here.

That pH scale we talked about is actually a measure of the number of H⁺ ions in a solution. If there are a lot of H⁺ ions, the pH is very low. If there are a lot of OH^- ions, that means the number of H⁺ ions is very low, so the pH is high.

That's basically it. (Ha Ha, get it?)