1130 words - 5 pages

Title: Modeling the electron Location in a Hydrogen atom

Purpose:

To determine where an electron is most likely when in its lowest energy state.

Introduction:

In the atomic models of the early 20th century, electrons were said to move around the nucleus along specific paths, much as the planets move around the sun.

According to the Bohr model of an atom, the electron is located in a precise orbit or energy level outside of the nucleus. Bohr labeled each energy level, and consequently each orbit, by a quantum number, n. For the lowest energy level, or the ground state, n = 1. This energy level corresponds to the orbit closest to the nucleus. When the electron absorbs the appropriate amount of energy, it “jumps” to a level of higher energy called an excited state. The excited states represent larger orbits with the electron farther from the nucleus.

Experimental evidence has indicated that the precise position of an electron in an atom cannot be known or predicted. Scientists can speak only of the probability of finding electrons at various locations, not of their exact positions. Probability is a measure of how often a certain event will occur out of a total number of events.

An electron cloud model provides a visual model of the probable behavior of an electron in an atom. In the current electron – cloud model of the atom, it is impossible to describe the exact positions of electrons; the model does describe the probability or chance that electrons will be found in certain locations around the nucleus.

The probability of finding an electron in various locations around the nucleus can be pictured in terms of a blurry cloud of negative charge. The cloud is most dense where the probability of finding the electron is highest. The cloud is least dense where the probability of finding the electron is lowest. The density of an electron cloud is referred to as electron density. Those regions or volumes of space of high probability are said to have high electron density. Conversely, regions of low probability are said to have low electron density. In summary, the electron - cloud model represents the most probable location of an electron at a single instant.

The probability of finding electrons in certain regions of an atom is described by orbitals. An atomic orbital is a region in space around the nucleus of an atom where an electron with a given energy is likely to be found. Rather than drawing electron clouds to represent orbitals, it is more convenient to draw the surface within which an electron is found 90 percent of the time. A sphere can be drawn that encloses 90 percent of the electron density. The probability of finding the electron is the same for all points on the surface, and there is a 90 percent chance of finding the electron within the sphere. In this investigation, you will use probability to describe the location on an electron in an atom.

Procedure:

1. Roll the die, note which number appears, and use a single cra...

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