Chemistry: Chapter 5 - Vocabulary
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Created by:
lioradickter on November 16, 2010
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20 terms
Terms | Definitions |
|---|---|
 Neils Bohr | A young Danish physicist and a student of Rutherford. (1885-1962) He proposed that an electron is found only in specific circular paths, or orbits, around the nucleus. |
| Energy Levels | Is what the fixed energies an electron can have are called. The amount of energy an electron gain or loses in an atom is not always the same. Like the rungs of the strange ladder in Figure 5.3b, the energy levels in an atom are not equally spaced. The higher energy levels are closer together. The higher the energy level occupied by an electron, the less energy it takes to move from that energy level to the next energy level. |
| Quantum | A quantum of energy is the amount of energy required to move an electron from one energy level to another energy level. The energy of an electron is said to be quantized. |
| Erwin Schrodinger | An Austrian physicist. (1887-1961) In 1926, used these new results to devise and solve a mathematical equation describing the behavior of the electron in a hydrogen atom. |
| Quantum Mechanical Model | The modern description of the electrons in atoms, the quantum mechanical model, comes from the mathematical solutions to the Schrodinger equation. Restricts the energy of electrons to certain values. Does not involve an exact path the electron takes around the nucleus. Determines the allowed energies an electron can have and how likely it is to find the electron in various location around the nucleus. |
| Atomic Orbital | For each energy level, the Schrodinger equation also leads to a mathematical expression, called an atomic orbital, describing the probability of finding an electron at various locations around the nucleus. Is often thought of as a region of space in which there is a high probability of finding an electron. The energy levels of electrons in the quantum mechanical model are labeled by principal quantum numbers (n). These are assigned the values n = 1, 2, 3, 4, and so forth. For each principal energy level constitute energy sublevels. Each energy sublevel corresponds to an orbital of different shape describing where the electron is likely to be found. Different atomic orbitals are denoted by letters. s orbitals are spherical, and p orbitals are dumbbell-shaped. |
| Electron Configurations | The ways in which electrons are arranged into various orbitals around the nuclei of atoms are called electron configurations. Three rules - the aufbau principle, the Pauli exclusion principle, and Hund's rule - tell you how to find the electron configurations of atoms. |
| Aufbau Principle | According to the aufbau principle, electrons occupy the orbitals of lowest energy first. Some actual electron configurations differ from those assigned using the aufbau principle because half-filled sublevels are not as stable as filled sublevels, but they are more stable than other configurations. |
| Pauli Exclusion Principle | According to the Pauli exclusion principle, an tomic orbital may describe at most two electrons. |
| Hund's Rule | It states that electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible. |
| Amplitude | The amplitude of a wave is the wave's height from zero to the crest. |
| Wavelength | The wavelength, represented by λ (the Greek letter lambda), is the distance between the crests. The wavelength and frequency of light are inversely proportional to each other. As the wavelength of light increases, for example, the frequency decreases. |
| Frequency | The frequency, represented by v (the Greek letter nu), is the number of wave cycles to pass a given point per unit of time. The units of frequency are usually cycles per second. The product of frequency and wavelength always equals a constant (c), the speed of light: c = λv |
| Hertz | The SI unit of cycles per second is called a hertz (Hz). A hertz can also be expressed as a reciprocal second. |
| Electromagnetic Radiation | According to the wave model, light consists of electromagnetic waves. Electromagnetic radiation includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays. |
| Spectrum | When sunlight passes through a prism, the different frequencies separate into a spectrum of colors. |
| Atomic Emission Spectrum | Each specific frequency of visible light emitted corresponds to a particular color. Therefore, when the light passes through the prism, the frequencies of light emitted by an element separate into discrete lines to give the atomic emission spectrum of the element. Each discrete line in an emission spectrum corresponds to one exact frequency of light emitted by the atom. |
| Ground State | The lowest possible energy of the electron is its ground state. |
| Photons | Light quanta are called photons. |
| Heisenberg Uncertainty Principle | The Heisenberg uncertainty principle states that it is impossible to know exactly both the velocity and the position of a particle at the same time. |
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