Protons, Electrons and Neutrons
By: Eesha S. 2011

What are protons, neutrons and electrons?
Protons, neutrons and electrons are the smallest pieces of matter that exist. These substances are parts of atoms. Atoms are part of elements. The amount of protons, neutrons and electrons determine certain qualities of an atom. Protons are positively charged and electrons are negatively charged. Neutrons have no charge.

This is a diagram of the inside of an atom. The blue dots are neutrons, the red ones are protons and the yellow ones are electrons. You can also see that in the first shell of an atom there are 2 electrons and in the second shell there are 8 electrons.

What is matter?
Matter makes up all objects in this universe. The very first ideas of matter were developed by the ancient Greeks. Thales thought that all matter was made out of water. Empedocles thought that matter consisted of the four elements- Earth, air, fire and water. Aristotle thought that there was another element called ether. Leucippus had another theory where there was one kind of matter. He thought that if matter was repeatedly cut up, it would be and uncuttable piece of mater. His follower, Democritus, called this uncuttable piece of matter an atom. But for the next 2,000 years, Aristotle’s theories were thought to be correct.

Democritus believed in many of Plato’s theories. He thought that for each element, there was a certain shape. For example, the atoms of Earth were thought to be cubes, which were packed together tightly to give it strength and stability. Fire atoms were thought to be solid shapes with four sides, called tetrahedrons. Air atoms were octahedrons, which were solid figures with eight faces. Water atoms were thought to be made up of icosahedrons, which were solid shapes with twenty triangular faces.

Types of matter:

Over time, people have come up with three different states of matter. These states are solids, liquids and gas. All types of matter classify into one of these three classes. Types of matter can be organized by their mass. For example, a brick has more mass than a feather.

The three states of matter, solids, liquids and gases, are found in our everyday lives. Some examples of solids are rocks, tables and boxes. Solids do not change their shape easily. For example, you can’t easily break a chair, or take it out of its shape. Some examples of liquids are water, milk and juice. The shape of a liquid changes based on its container. For example, when you pour lemonade from a pitcher into a glass, it changes shape. Some examples of gases are air and helium. Matter in the state of gas doesn’t have a certain shape or size. It can be used to fill a container or be squeezed into a smaller space.

How does matter change?

Different types of matter can be changed in different ways. Solids can be changed into liquids by heating them up to a temperature called a melting point. Liquids can be changed into gases by heating it up to a temperature called its boiling point. A good example of a liquid changing into solid is the moment a volcano erupts. A volcano erupts lava. The lava is in liquid form. As the lava touches the surface of the volcano, it cools and becomes stone. An example of a solid changing into a liquid is when you warm up ice. Ice has a boiling point of 32° Fahrenheit.

What are atoms?
Atoms are part of elements. In other words, each element is made up of atoms. Atoms are made up protons, electrons and neutrons, also called subatomic particles. Together, protons, neutrons and electrons, are called nucleons. Protons, neutrons and electrons are made up of even smaller particles, called quarks. The center of an atom is called a nucleus. The nucleus is pushed together by the strong nuclear force. The nucleus is made up of protons and neutrons. Protons are positively charged and neutrons have no charge. Around the nucleus are electrons. Electrons are negatively charged.

This picture is of the nucleus and the electrons around it.
Important properties of atoms:
Atomic Number: The most important thing to know about an atom is the number of protons in its nucleus. This number is called the atomic number. The atomic number determines what kind of atom it is. Each atom is paired with an element. Each atom’s atomic number is unique. For example, hydrogen has an atomic number of 1 because it has one proton in its nucleus. No other elements have an atomic number of 1.

Mass Number: Another important thing to know about an atom is its mass number. The mass number is the total amount of protons and neutrons in an atom.

Atomic Weight: Another important thing to know about an atom is its atomic weight. The atomic weight of an atom is the mass number divided by a certain number that scientists have come up with.

The mass number and atomic weight are very similar. For example, the mass number of carbon is 12, and the atomic weight is 12.011. Atoms that have the same atomic number but different mass numbers are called isotopes. For example, carbon-12 is the ordinary form of carbon. It has 6 protons and 6 neutrons per atom. Carbon-14 is an isotope with 8 neutrons per atom. Carbon-14 still has 6 protons. If it didn’t have 6 protons, it wouldn’t be carbon.

Chemical compounds:
Ordinary atoms have the same number of protons and electrons, so the electrical charges are balanced. Sometimes, when chemicals mix together and form compounds, an atom loses or gains a proton, neutron or electron. Ordinary atoms that lose or gain an electron are called ions. If an atom loses an electron, it is called a positive ion. If it gains an electron, it is called a negative ion.

This is a picture of the way that elements bond to become compounds.

"Atom." Britannica Elementary Encyclopedia. Encyclopædia Britannica Online School Edition.

Encyclopædia Britannica, Inc., 2011. Web. 20 Sept. 2011.

Cooper, Christopher Matter. New York: Dorling Kindersley, 1992, Print
Elements of Physics: Matter: Atoms and Molecules
Elements of Physics: Matter: Atoms and Molecules. Prod. Discovery Education. Discovery Education, 2006. Discovery Education. Web. 22 September 2011.

"Matter." Britannica Elementary Encyclopedia. Encyclopædia Britannica Online School Edition.

Encyclopædia Britannica, Inc., 2011. Web. 20 Sept. 2011.

Empedocles: famous Greek scientist that studied in the 5th century B.C.
Electron: small particle found in an atom, negative charge
Hydrogen: element with an atomic number of 1
Icosahedron: solid shape with twenty triangular faces
Neutron: particle found inside an atom, no charge
Octahedron: solid shape with eight faces
Proton: particle found inside an atom, positive charge
Quarks: particle found inside protons, neutrons and electrons
Subatomic: another name for the type of particles that protons, neutrons and electrons are
Tetrahedron: solid shape with four sides