Climate Change. Climate Feedback. Ocean Acidification. Rising Sea Level. Ionization Figure 1. Simplified ionization process where an electron is removed from an atom. May 14, Compendium of Chemical Terminology [Online], 2nd ed.
July 31, 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.
If charged, indicate whether they are charged positively or negatively. Chemically, we say that the atoms have formed bonds. In contrast to neutral atoms, the field due to an ionized atom is strong, even at larger distances.
The strong electric field of ions makes them strongly attracted to other atoms and molecules, to the point of being highly chemically reactive. Ionized atoms can be free radicals, which are atoms with a dangling bond that are highly reactive. In the human body, free radicals can react with DNA, leading to mutations and possibly cancer. Atoms become ionized when light with enough energy knocks off some of their electrons.
Only light waves at the frequencies of X-rays and gamma rays have enough energy to ionize atoms and therefore lead to cancer. The cancer-causing power of only certain frequencies is why you can use your cell phone as much as you want, but you can only get an X-ray image taken on rare occasions.
The addition of one more electron gives the halide ions the same electron configuration as a noble gas, which we have seen is particularly stable. Period and group trends for electron affinities are not nearly as regular as for ionization energy. In general, electron affinities increase become more negative from left to right across a period and decrease become less negative from top to bottom down a group.
However, there are many exceptions, owing in part to inherent difficulties in accurately measuring electron affinities. Use the link below to answer the following questions:. Skip to main content. The Periodic Table. Search for:. Electron Affinity Learning Objectives Define electron affinity. Describe trends in electron affinity in the periodic table.
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