Electricity and the Atomic Structure
Electricity is all around us. Electricity powers the modern world like our phones, computers, lights, refrigerators, even our bodies, all require electricity to work. This page will explore the relationship of electricity down to the atomic structure. It is important to understand the Atomic model because at its most basic electricity is defined as the flow of electric charge. Electric charge is property that leads to electromagnetic interactions between the particles that make up matter.
The Building Blocks of Atoms
An atom is built with a combination of three distinct particles:
Electrons
Protons
Neutrons
Charges can be + , – , or neutral. The movement of electrons from atom to atom is how electricity is created. Electrons always carry a negative charge, while protons are always positively charged. Neutrons (true to their name) are neutral, they have no charge. Both electrons and protons carry the same amount of charge, just a different type. The center of an atom, or nucleus, is where the protons and neutrons are densely packed together. Orbiting around the nucleus are the electrons with the outer most orbit of these called valence electrons.
Valence Electrons
Electrons surround the nucleus of an atom in what are known as shells. The easiest way to picture these shells are as rings around the nucleus and there are a set number of electrons that each shell can hold. Once a shell fills with electrons the next electron tied to that atom will move outwards to the next shell. The electrons on the outermost shell of any atom, regardless of the number of shells, are known as the valence electrons.
The presence of valence electrons can determine the atom's chemical properties. An atom's reactivity is highly dependent upon its electron configuration:
Atoms with a full shell of valence electrons tend to be chemically inert.
Atoms with one or two valence electrons are highly reactive due to the relatively low energy to remove the extra valence electrons to form a positive ion (ion: an atom with an unequal amount of electrons and protons).
Atoms with one or two electrons less than a full shell are reactive due to their tendency to either gain the missing valence electrons and form a negative ion, or else to share valence electrons and form a covalent bond.
Electric Charge
When an atom loses or gains electrons it becomes an ion and gains a positive or negative charge. When an atom gains electrons it becomes negative and when it loses electrons it becomes positive. Charging objects happens when atoms gain or lose electrons, and can happen three ways:
By Friction: when objects rub on each other, electrons are transferred.
By Contact: when two objects touch, electrons can transfer.
By Induction: rearranging charges without touch
Electrostatic Force (Coulomb’s law)
Electrostatic force is a force that operates between charges. It states that charges of the same type push or repel each other, while charges of opposite types pull or are attracted together. Opposite charges attract, and like charges repel.
The amount of electrostatic force acting on two charges depends on:
How far apart they are from each other.
Magnitudes of charges.
Electron Flow
With enough outside force, a valence electron – either pushing it with another negative charge or attracting it with a positive charge – can escape the orbit of the atom and become free. Free electrons allow us to move charge, which is what electricity is all about.
Conductivity
Some atoms are better than others at releasing their electrons. To get the best possible electron flow we want to use atoms that don’t hold very tightly to their valence electrons. An element’s conductivity measures how tightly bound an electron is to an atom.
Elements with high conductivity, which have very mobile electrons, are called Conductors. Metals like copper, silver, and gold are usually our top choices for good conductors.
Elements with low conductivity are called Insulators. Insulators serve a very important purpose: they prevent the flow of electrons. Popular insulators include glass, rubber, plastic, and air.
Conductivity Classifications
Conductor
Conductors are materials with a low number of valence electrons. These materials allow charge to flow easily.
Insulator
Insulators are materials with a high number of valence electrons. The materials are typically molecules whose atoms have strong bonds with each other. These materials don't allow charge to flow easily.
Semiconductor
Semi Conductors are molecules whose pairs fill their valence electron shell. These molecules are then doped so that they have one or more additional free or missing electrons. These materials allow charge to flow at different rates depending on design.
Experiment with Charge! Build an Electroscope
An electroscope is an early scientific instrument used to detect the presence of electric charge on a body. An electroscope can only give a rough indication of the quantity of charge.
What you'll need:
1 - Glass or Plastic Jar
1 - Non Conductive Plastic or Cork Lid
1 - 14 AWG Stripped Wire (Romex Wire)
2 - SqIn of Aluminum Foil
1 - Wire Stripper
Objective
The objective of creating an electroscope is to design and construct a simple yet effective device that can detect the presence and nature of electric charges. The electroscope will serve as a reliable tool for demonstrating and investigating static electricity, allowing users to observe and understand the behavior of charged objects and the principles of electrostatics. The primary goals of this project include:
Construction: Build an electroscope using easily accessible materials, such as a conducting 14 AWG wire, lightweight aluminum foil leaves, an insulating support, and a suitable housing, to create a functional and durable device.
Sensitivity: Ensure the electroscope is sensitive enough to detect even small amounts of charge, enabling users to observe and measure the presence of both positive and negative electric charges accurately.
By achieving these objectives, the created electroscope will provide an effective tool for scientific experiments, classroom demonstrations, and personal exploration, promoting a better understanding of electrostatic phenomena and fostering an interest in physics and electrical phenomena among users.
Step One
Take any jar or container that has a lid and poke a hole in the lid.
Step Two
Grab an 18" piece of 14 gauge solid core wire and coil one end.
Step Three
Insert the straight end of your wire through the hole in the lid and bend the end into a hook. The hook should be about 2 inches above the bottom of the container.
Step Four
Create tear drop shaped tabs made from aluminum foil about a quarter in size. Poke a small hole near the top.
Step Five
Add the tabs to the hook. Now, any time a charge is brought near your coil, your tabs will separate.
Challenge once Built!
After building an electroscope, there are several activities you can engage in to explore its functionality and deepen your understanding of electrostatics. Here are a few activities you can try:
Charge Induction: Use different objects, such as plastic rods, glass rods, or balloons, to generate static charges by rubbing them against different materials. Bring the charged object close to the electroscope and observe the behavior of the metal leaves. Note whether they repel or attract each other, and record your observations.
Charge Transfer: Experiment with charging the electroscope by touching it with different objects that carry a charge, such as a charged balloon or a metal rod. Observe the response of the electroscope and note how the metal leaves behave when the charged object comes in contact with it.
Charging by Contact: Charge the electroscope by rubbing it with different materials, such as fur or silk. Observe the behavior of the metal leaves as they respond to the charged electroscope. Compare and contrast the observations with the charging methods mentioned in activity 2.
Distance and Charge Distribution: Explore how the distance between a charged object and the electroscope affects the deflection of the metal leaves. Move the charged object closer or farther away and record the corresponding changes in the deflection angle. Note any patterns or relationships you observe.
Shielding Effects: Introduce a conductor, such as a metal plate or foil, between the charged object and the electroscope. Observe how the presence of the conductor affects the deflection of the metal leaves. Investigate the concept of electrostatic shielding and its impact on the electroscope's behavior.
Remember to keep detailed records of your observations and findings during each activity. These activities will not only enhance your understanding of electrostatics but also enable you to develop a deeper appreciation for the behavior of electric charges and the principles underlying the electroscope's operation.