Electron Activity in Chemical Reactions | Batteries And Power Systems | Electronics Textbook
All atoms are made up of three basic subatomic particles: protons, neutrons, and electrons. Protons and neutrons are found in the nucleus of the atom, with. Purpose. To explore atomic structure. Protons carry a positive charge (+), and electrons carry a negative charge (-). The number of electrons in an All About Atoms—This resource has only a couple of pages to it. Students can click on a. The number of protons, neutrons, and electrons in an atom can be The number of protons in the nucleus of the atom is equal to the atomic number (Z).
Furthermore, it was known that different wavelengths of light corresponded to different amounts of energy. In one of the first developments in quantum mechanics, Max Planck in proposed that light travels in bundles called photons. Although they are particles, these photons do have wave properties. The amount of energy in a photon of light corresponds to its wavelength. By proposing that electrons could be found only in specific orbits, specific distances away from the nucleus, Bohr was trying to explain observations from atomic spectroscopy reported by another scientist named Rydberg.
Rydberg had found a mathematical relationship between the wavelengths of these emission lines. Bohr thought that, when energy was added, electrons could be excited from one energy level or orbit to a higher one. When the electron relaxed back to its original orbit, it gave off the energy it had gained in the form of light.
The specific emission lines occur because electrons are found at very specific energy levels in an atom, so a drop from one level to another always produces the same amount of light energy.
Protons, Neutrons, and Electrons
That specific amount of light energy has a specific colour. The correspondence between colour, wavelength and energy.
Bohr then used the mathematical relationships describing electrostatic attraction and centripetal force to show that his model of the atom was consistent with Rydberg's relationship. In fact, he could use his model to predict the emission lines of an atom.
The periodic table, electron shells, and orbitals
Bohr's explanation of atomic structure built on Rydberg's observation of a numerical series in spectral emission lines. Solving a series involves finding a pattern in numbers. Find the patterns among the following sequences of numbers, and predict the next number in the sequence. Bohr's idea depended partly on the use of Coulomb's Law of electrostatic attraction. Coulomb's law is expressed mathematically as follows: A large value of F means that the charges are strongly attracted to each other.
What happens to the force of attraction between an electron and the nucleus when the charge in the nucleus increases? What happens to the force of attraction between an electron and nucleus when the electron gets further from the nucleus? Max Planck described the energy of a photon using the following relationship: Other people were familiar with these ideas and already knew about the relationship between light and energy. Bohr's model of the atoms put all of these ideas together to successfully explain a specific atomic property: In other words, an excited electron can drop back to its original orbit by giving off a photon with an energy exactly the same as the difference in energy between the two orbits "excited state" and "ground state" orbits.
An electron can be thought of as both a particle and a wave. However, Bohr did not explain why electrons would be found at specific energy levels in the first place. Louis de Broglie, a historian-turned-physicist, solved this problem with the idea of wave-particle duality.
All moving particles have wave properties. Electrons move around the nucleus and they have wavelengths. To maintain a complete standing wave along its orbit, an electron can only adopt orbits of specific circumferences. Otherwise, one end of the wave would not meet up with the other end, and it would interfere with itself.
Orbits with specific circumferences have specific radii. Electrons are found at specific distances from the nucleus, but not at other distances. One way to illustrate why an electron might have only certain allowed orbits is via the "particle in a box", a basic concept from quantum mechanics.
If a particle has wave properties, then it has a wavelength. Its wavelength depends on certain conditions. By analogy, if you take a guitar string and attach it to the ends of a box, the string can only vibrate at certain frequencies. That's how guitarists can change the note played on a guitar string.
By pressing one end of the string against a fret on the guitar neck, the length of the string is changed, and so is its allowed wavelength, so it makes a different sound. The string can't move at the two points where it is held. That means the wave has to form in such a way that it returns to the same position at both ends. Because of that, certain wavelengths won't work, because the wave won't be able to return to that correct position at the far end.
Furthermore, the allowed wavelengths of a guitar string also depend on the thickness of the string. Procedure, part 3 2 pieces of charged plastic Charge two strips of plastic Slowly bring the two strips of plastic near each other.
- Matter, elements, and atoms
- Electron Activity in Chemical Reactions
- Static Electricity 1: Introducing Atoms
Expected results The strips will move away or repel each other. Since both strips have extra electrons on them, they each have extra negative charge. Since the same charges repel one another, the strips move away from each other. 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 Small pieces of paper, confetti-size Procedure Rub a balloon on your hair or clothes. Bring the balloon slowly toward small pieces of paper. Expected results The pieces of paper will jump up and stick on the balloon. What did you observe when the charged balloon was held near the pieces of paper?
The paper pieces moved up and stuck on the balloon. Use what you know about electrons, protons, and charges to explain why this happens. When you rub the balloon on your hair or clothes it picks up extra electrons, giving the balloon a negative charge.
When you bring the balloon near the paper, the electrons from the balloon repel the electrons in the paper.
Structure of the Atom
Since more protons are at the surface of the paper, it has a positive change. The electrons are still on the paper, just not at the surface, so overall the paper is neutral.
Opposites attract, so the paper moves up toward the balloon. In this simulation, you can rub the balloon a little bit on the sweater and see that some of the electrons from the sweater move onto the balloon. This gives the balloon a negative charge. For example, a gold coin is simply a very large number of gold atoms molded into the shape of a coin, with small amounts of other, contaminating elements. Gold atoms cannot be broken down into anything smaller while still retaining the properties of gold.
A gold atom gets its properties from the tiny subatomic particles it's made up of. An atom consists of two regions. The first is the tiny atomic nucleus, which is in the center of the atom and contains positively charged particles called protons and neutral, uncharged, particles called neutrons. The attraction between the positively charged protons and negatively charged electrons holds the atom together.
Most atoms contain all three of these types of subatomic particles—protons, electrons, and neutrons. Hydrogen H is an exception because it typically has one proton and one electron, but no neutrons.
The number of protons in the nucleus determines which element an atom is, while the number of electrons surrounding the nucleus determines which kind of reactions the atom will undergo.