Write the complete electron configuration for the beryllium atom. Using the noble gas abbreviation, rewrite the electron configuration for the beryllium atom. [He] 2s2
The Correct Answer and Explanation is:
Of course. Based on the provided image and the principles of chemistry, here are the correct answers and a detailed explanation.
Correct Answer for “Write the complete electron configuration for the beryllium atom”:
1s²2s²
Correct Answer for “Using the noble gas abbreviation rewrite the electron configuration for the beryllium atom”:
[He]2s²
Explanation
To determine the electron configuration of an atom, we must first identify how many electrons it has and then fill the atomic orbitals according to a set of rules.
1. Finding the Number of Electrons
Beryllium (Be) is element number 4 on the periodic table. Its atomic number is 4, which means a neutral beryllium atom has 4 protons and 4 electrons. Our goal is to assign these 4 electrons to specific orbitals.
2. The Complete Electron Configuration
The complete, or full, electron configuration lists all the filled orbitals starting from the lowest energy level. We follow the Aufbau principle, which states that electrons fill orbitals in order of increasing energy (1s, then 2s, then 2p, etc.).
- The first two electrons fill the lowest energy orbital, the 1s orbital. This is written as 1s². The superscript ‘2’ indicates two electrons are in that orbital.
- We have two electrons remaining (4 total – 2 used). These next two electrons go into the next lowest energy orbital, which is the 2s orbital. This is written as 2s².
Combining these gives the complete electron configuration for beryllium: 1s²2s².
In the image provided, the answer [He]2s² was marked incorrect for this question because it is the abbreviated form, not the complete one the question asked for.
3. The Noble Gas Abbreviation
The noble gas configuration is a convenient shorthand. It uses the symbol of the noble gas from the previous period to represent the “core” electrons.
- Beryllium is in Period 2 of the periodic table. The noble gas at the end of the previous period (Period 1) is Helium (He).
- The electron configuration of Helium is 1s².
- We can replace the 1s² part of beryllium’s full configuration (1s²2s²) with the symbol [He] in brackets.
- We then write the remaining electrons, which are the valence electrons. For beryllium, this is 2s².
This gives the noble gas abbreviation for beryllium: [He]2s².
The answer [Ar]3d¹⁰4s²4p⁵ shown in the image is the configuration for Bromine (Br), a much larger atom with 35 electrons, and is therefore incorrect for beryllium.
