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Ch.6 - Electronic Structure of Atoms
Chapter 6, Problem 77a

Identify the specific element that corresponds to each of the following electron configurations and indicate the number of unpaired electrons for each: (a) 1s22s2

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Identify the highest energy level and the corresponding electrons from the given electron configuration. In this case, the configuration is 1s2 2s2.
Determine the element by matching the total number of electrons from the electron configuration to the atomic number on the periodic table. The sum of electrons here is 4, which corresponds to the atomic number of Beryllium (Be).
Analyze the electron configuration to identify unpaired electrons. Electrons that are alone in an orbital are considered unpaired.
Examine the 1s and 2s orbitals. In the given configuration, both 1s and 2s orbitals are fully filled (each has 2 electrons), which means they are paired.
Conclude that there are no unpaired electrons in the electron configuration 1s2 2s2 for Beryllium (Be).

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Key Concepts

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

Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. It is represented by a series of numbers and letters that indicate the energy levels and types of orbitals occupied by electrons. For example, '1s²2s²' indicates that there are two electrons in the 1s orbital and two in the 2s orbital, which helps determine the element's identity and its chemical properties.
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Periodic Table

The periodic table organizes elements based on their atomic number and electron configurations. Each element's position in the table reflects its electron arrangement, which influences its reactivity and bonding behavior. By analyzing the electron configuration '1s²2s²', one can identify the element as beryllium (Be), which is located in group 2 of the periodic table.
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Unpaired Electrons

Unpaired electrons are those that occupy an orbital alone rather than in pairs. The presence of unpaired electrons is crucial for understanding an element's magnetic properties and its ability to form bonds. In the case of the configuration '1s²2s²', all electrons are paired, resulting in zero unpaired electrons, indicating that beryllium is not paramagnetic.
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