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Ch. 2 - General Chemistry Translated: Finding the Electrons
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
Chapter 1, Problem 15a

How many electrons does an atom of each of the following elements need to gain to achieve a noble gas configuration? By gaining that many electrons, which noble gas configuration is achieved?
(a) Oxygen

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1
Step 1: Understand the problem. To achieve a noble gas configuration, an atom must have a full outer electron shell. For oxygen, determine how many electrons are needed to complete its valence shell.
Step 2: Recall the electronic configuration of oxygen. Oxygen has an atomic number of 8, meaning it has 8 electrons. Its electron configuration is: 1s22s22p4. The valence shell (n=2) contains 6 electrons (2 from 2s and 4 from 2p).
Step 3: Determine how many electrons are needed to fill the valence shell. A full valence shell for oxygen requires 8 electrons. Since oxygen already has 6 valence electrons, it needs to gain 2 more electrons to achieve a full shell.
Step 4: Identify the noble gas configuration achieved. By gaining 2 electrons, oxygen will have the electron configuration of 1s22s22p6, which corresponds to the noble gas neon (atomic number 10).
Step 5: Summarize the findings. Oxygen needs to gain 2 electrons to achieve a noble gas configuration, and by doing so, it attains the electron configuration of neon.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Noble Gas Configuration

Noble gas configuration refers to the electron arrangement of noble gases, which have full outer electron shells, making them stable and unreactive. Atoms tend to gain, lose, or share electrons to achieve this stable configuration, typically resembling the nearest noble gas in the periodic table.
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The Electron Configuration

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom that are involved in chemical bonding. The number of valence electrons determines how an atom interacts with others, including how many electrons it needs to gain or lose to achieve a noble gas configuration.
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Electron Gain and Ionic Charge

When an atom gains electrons, it becomes negatively charged, forming an anion. The number of electrons gained corresponds to the difference between the atom's current valence electron count and the eight electrons needed for a full outer shell, which is characteristic of noble gases.
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Calculating formal and net charge.