When it comes to neutrons, the answer is obvious. Since neutrons are neither attracted to nor repelled from objects, they don't really interact with protons or electrons beyond being bound into the nucleus with the protons.
Even though electrons, protons, and neutrons are all types of subatomic particles, they are not all the same size. When you compare the masses of electrons, protons, and neutrons, what you find is that electrons have an extremely small mass, compared to either protons or neutrons.
On the other hand, the masses of protons and neutrons are fairly similar, although technically, the mass of a neutron is slightly larger than the mass of a proton. Because protons and neutrons are so much more massive than electrons, almost all of the mass of any atom comes from the nucleus, which contains all of the neutrons and protons.
The third column shows the masses of the three subatomic particles in "atomic mass units. Negative and positive charges of equal magnitude cancel each other out. This means that the negative charge on an electron perfectly balances the positive charge on the proton.
In other words, a neutral atom must have exactly one electron for every proton. If a neutral atom has 1 proton, it must have 1 electron. If a neutral atom has 2 protons, it must have 2 electrons. If a neutral atom has 10 protons, it must have 10 electrons. You get the idea. In order to be neutral, an atom must have the same number of electrons and protons. And neutral objects have a balance of charge - equal numbers of protons and electrons.
The principle stated earlier for atoms can be applied to objects. Objects with more electrons than protons are charged negatively; objects with fewer electrons than protons are charged positively. In this discussion of electrically charged versus electrically neutral objects, the neutron has been neglected. Neutrons, being electrically neutral play no role in this unit. Their presence or absence will have no direct bearing upon whether an object is charged or uncharged. Their role in the atom is merely to provide stability to the nucleus, a subject not discussed in The Physics Classroom.
When it comes to the drama of static electricity, electrons and protons become the main characters. Like mass, the charge of an object is a measurable quantity.
The charge possessed by an object is often expressed using the scientific unit known as the Coulomb. Just as mass is measured in grams or kilograms, charge is measured in units of Coulombs abbreviated C. To illustrate the magnitude of 1 Coulomb, an object would need an excess of 6. And of course an object with a shortage of 6. The charge on a single electron is The quantity of charge on an object reflects the amount of imbalance between electrons and protons on that object.
Thus, to determine the total charge of a positively charged object an object with an excess of protons , one must subtract the total number of electrons from the total number of protons. This operation yields the number of excess protons.
A similar process is used to determine the total charge of a negatively charged object an object with an excess of electrons , except that the number of protons is first subtracted from the number of electrons. In conclusion, an electrically neutral object is an object that has a balance of protons and electrons.
In contrast, a charged object has an imbalance of protons and electrons. Determining the quantity of charge on such an object involves a counting process ; the total number of electrons and protons are compared to determine the difference between the number of protons and electrons.
This difference is multiplied by 1. The type of charge positive or negative is determined by whether the protons or the electrons are in excess. Use your understanding of charge to answer the following questions. When finished, click the button to view the answers.
Negatively charged objects have protons; it's just their number of electrons is greater than their number of protons. Electrically neutral atoms simply possess the same number of electrons as protons. This gives the objects a balance of both type of charge. Identify the following particles as being charged or uncharged.
This electron is immediately picked up by a chlorine atom and fitted into the last empty space in its outermost orbital. Now both atomic arrangements are much more stable. They both have outermost orbitals which are filled with electrons.
However, there is a price to be paid for this stability. In giving up an electron, the sodium atom has lost a negative electrical charge. It still has all its positively charged protons, so the remaining structure is no longer electrically neutral.
Similarly, the chorine atom has picked up this extra negative charge and no extra protons, so it is now carrying a net negative charge -. These new atomic arrangements are called ions , and the process of electron exchange is called ionization.
Ionic bonds are a type of linkage formed from the attraction between oppositely charged ions. Such bonds are created when the outermost electrons of one atom such as sodium are transferred permanently to another atom such as chlorine. The atom that has lost an electron becomes a positively charged ion called a cation , while the atom that picks up the extra electron becomes a negatively charged ion called an anion.
You may want to mention that hydrogen is the only atom that usually has no neutrons. The nucleus of most hydrogen atoms is composed of just 1 proton. A small percentage of hydrogen atoms have 1 or even 2 neutrons. Atoms of the same element with different numbers of neutrons are called isotopes.
These will be discussed in Lesson 2. What zooms around the nucleus of an atom? Electrons Which one has a positive charge, a negative charge, and no charge? Proton—positive; electron—negative; neutron—no charge.
The charge on the proton and electron are exactly the same size but opposite. The same number of protons and electrons exactly cancel one another in a neutral atom.
Show animations and explain that protons and electrons have opposite charges and attract each other. Project the animation Hydrogen Atom. Give each student an activity sheet.
Explore Do an activity to show that electrons and protons attract each other. Question to investigate What makes objects attract or repel each other? Materials for each group Plastic grocery bag Scissors Procedure, part 1 Charged plastic and charged skin Cut 2 strips from a plastic grocery bag so that each is about 2—4 cm wide and about 20 cm long.
Quickly pull your top hand up so that the plastic strip runs through your fingers. Do this three or four times. Allow the strip to hang down. Then bring your other hand near it. Expected results The plastic will be attracted to your hand and move toward it. Explain Show students models comparing the number of protons and electrons in the plastic and skin before and after rubbing them together.
Explore Have students investigate what happens when a rubbed plastic strip is held near a desk or chair. Procedure, part 2 Charged plastic and neutral desk Charge one strip of plastic the same way you did previously. This time, bring the plastic strip toward your desk or chair.
Expected results The plastic moves toward the desk. Have students charge two pieces of plastic and hold them near each other to see if electrons repel one other. Ask students to make a prediction: What do you think will happen if you charge two strips of plastic and bring them near each other? Procedure, part 3 2 pieces of charged plastic Charge two strips of plastic Slowly bring the two strips of plastic near each other.
Expected results The strips will move away or repel each other. Ask students: What happened when you brought the two pieces of plastic near each other? The ends of the strips moved away from each other. Use what you know about electrons and charges to explain why this happens. Each strip has extra electrons so they are both negatively charged.
Because like charges repel, the pieces of plastic repelled each other. Explore Have students apply their understanding of protons and electrons to explain what happens when a charged balloon is brought near pieces of paper. Materials for each group Inflated balloon Small pieces of paper, confetti-size Procedure Rub a balloon on your hair or clothes. Bring the balloon slowly toward small pieces of paper.
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