| Atoms, the smallest particles of matter that retain the properties of the matter, are made of protons, electrons, and neutrons. |
Atoms are the smallest units of matter and consist of protons, electrons, and neutrons. |
| Protons have a positive charge, Electrons have a negative charge that cancels the proton's positive charge. |
Protons carry a positive charge, while electrons carry a negative charge that balances the positive charge of protons. |
| Neutrons are particles that are similar to a proton but have a neutral charge. |
Neutrons are similar to protons but have no electrical charge. |
| There are no differences between positive and negative charges except that particles with the same charge repel each other and particles with opposite charges attract each other. |
Like charges repel each other, while opposite charges attract each other. |
| If a solitary positive proton and negative electron are placed near each other they will come together to form a hydrogen atom. |
A positive proton and a negative electron attract each other and form a hydrogen atom. |
| This repulsion and attraction (force between stationary charged particles) is known as the Electrostatic Force and extends theoretically to infinity, but is diluted as the distance between particles increases. |
This attraction and repulsion is called the electrostatic force. It becomes weaker as the distance between particles increases. |
| When an atom has one or more missing electrons it is left with a positive charge, and when an atom has at least one extra electron it has a negative charge. |
Losing electrons makes an atom positively charged, while gaining electrons makes it negatively charged. |
| Having a positive or a negative charge makes an atom an ion. |
Any atom with a net positive or negative charge is called an ion. |
| Atoms only gain and lose protons and neutrons through fusion, fission, and radioactive decay. |
Atoms gain or lose protons and neutrons only through fusion, fission, or radioactive decay. |
| Although atoms are made of many particles and objects are made of many atoms, they behave similarly to charged particles in terms of how they repel and attract. |
Atoms and larger objects show similar attraction and repulsion behavior due to electric charges. |
| In an atom the protons and neutrons combine to form a tightly bound nucleus. |
Protons and neutrons join together to form the atom's nucleus. |
| This nucleus is surrounded by a vast cloud of electrons circling it at a distance but held near the protons by electromagnetic attraction (the electrostatic force discussed earlier). |
Electrons move around the nucleus and are held near it by electromagnetic attraction. |
| The cloud exists as a series of overlapping shells / bands in which the inner valence bands are filled with electrons and are tightly bound to the atom. |
Electrons occupy energy shells or bands. The inner valence bands are filled with tightly bound electrons. |
| The outer conduction bands contain no electrons except those that have accelerated to the conduction bands by gaining energy. |
The outer conduction bands are usually empty unless electrons gain enough energy to move into them. |
| With enough energy an electron will escape an atom (compare with the escape velocity of a space rocket). |
If an electron gains sufficient energy, it can leave the atom completely. |
| When an electron in the conduction band decelerates and falls to another conduction band or the valence band a photon is emitted. |
When an energized electron loses energy and moves to a lower energy level, it emits a photon (light particle). |
| This is known as the photoelectric effect. |
This phenomenon is called the photoelectric effect. |
