Beryllium was discovered by Nicolas-Louis Vauquelin. It is steel grayish in appearance and is brittle at room temperature. It is the lightest member of alkaline earth metals and is used as a hardening agent in metallurgy. It is distributed in the earth’s crust and is found in igneous rocks. Hello friends! We are here again with another interesting element to help you with its Bohr model. In this article, we will talk about Beryllium.
Bohr Model of Beryllium
In 1911, Rutherford proposed a model of the atom that tried to explain its various properties. However, this model could not stand up to certain concepts of classical mechanics and electromagnetic theory and thus, was rejected by the scientific society. Later, in 1913, Bohr in collaboration with Rutherford proposed another model explaining the structure of the atom, which was actually an improved version of the previous model. It is a visual representation of the atomic structure and is popularly known as the Bohr-Rutherford model or simply, the Bohr model of the atom. This model overcame most drawbacks of the earlier model and stands correct on various concepts even to date. The Bohr model explains the stability of the atom and atomic particles. It also talks about the position of various atomic particles inside the atom as well as their charge and other properties. It describes the structure of the atom in detail. The Bohr-Rutherford model defines the nucleus as the center or core of the atom inside which the entire positive charge of the atom remains confined. Protons reside inside the nucleus and are responsible for their positive charge. These are also responsible for maintaining charge balance inside the atom. Neutrons are also located inside the nucleus of the atom and are charge-neutral species. They play important role in determining various properties of an atom. Electrons are also a type of atomic species that carry a negative charge. They do not reside inside the nucleus rather revolve around it. They take a circular path while moving around the nucleus, which is known as the shell. Every atom contains a definite number of shells depending upon the number of electrons present in it. These are named as K, L, M, N, etc, or 1, 2, 3, 4, etc. shells. Every shell has a fixed electron carrying capacity i.e. it can only carry a definite number of electrons. Also, each shell has a certain amount of energy bound to it, due to which they are sometimes also called Energy levels. The electrons have a unique ability to move from one energy level to another based on their state of energy. This energy increases with the number of the shell due to which the outermost shell carries maximum energy, it is known as the valence shell and the electrons located in this shell are called valence electrons. The argon atom contains 5 neutrons, 4 protons, and 4 electrons. The electrons revolve around the nucleus in two shells i.e. K and L shells or 1 and 2 shells, respectively.
Drawing the Bohr Model of Beryllium
Beryllium is a member of the alkaline-earth metal family and is placed in group 2 (IIa) of the periodic table. The position of Beryllium is described in the figure below:
The information that we can derive from the above-mentioned Beryllium box is as follows: • The atomic number of Beryllium is 4. • [He] 2s2 is the electronic configuration of Beryllium. • The chemical symbol of Beryllium is Be. • Beryllium has an atomic mass of 9.012. With the help of the above information, we can draw the Bohr atomic model of the Beryllium atom. Keep reading to know-how. As discussed in the previous section, the Bohr model visually represents the position of various atomic species. Therefore, we must first find out the number of these atomic species. As the nucleus constitutes the center of an atom, we will begin with calculating the number of protons and neutrons inside the nucleus. The number of protons in an atom is equal to the atomic number of that atom. In the case of the Beryllium atom, the atomic number is 4. Therefore, the number of protons in the Beryllium atom is also 4. Further, we will calculate the number of neutrons in this atom. The number of neutrons in an atom is calculated using the following formula: Number of neutrons = Number obtained by rounding atomic mass of the atom up to the nearest whole number – Number of protons in the atom In the case of the Beryllium atom, the atomic mass is 9.012. Rounding it up to the nearest whole number we get 9. Therefore, the number of neutrons in the Beryllium atom = 9 – 4 =5 Now, that we have calculated the number of both the atomic species i.e. protons and neutrons, we can draw the nucleus of the Beryllium atom using the postulates of the Bohr atomic model.
The above diagram illustrates the nucleus of the Beryllium atom. Once we have drawn the nucleus of the atom, we can now move on to calculate the number of electrons in this atom. The number of electrons in an atom is equal to the atomic number of that atom. In the case of the Beryllium atom, atomic number = 4 Therefore, the number of electrons in the Beryllium atom = 4 Now, we will decipher the position of these electrons inside the atom. We have learned in the previous section that the electrons are located outside the nucleus and are housed in different shells as per their energies. Beginning from the lowest shell we will calculate the number of electrons that can be housed in one shell. The K shell is located nearest to the nucleus of an atom. Hence, we will begin with the K shell. The maximum number of electrons that a shell can accommodate or the electron carrying capacity of a shell is given by the formula 2n2. Therefore, the electron carrying capacity of the K shell = 2n2 = 2 X (1)2 = 2 Hence, the K shell can carry a maximum of 2 electrons. Thus, we will accommodate 2 out of the 4 electrons of the Beryllium atom in its K shell.
After this step, we are now left with 2 more electrons. So, we will first calculate the maximum electrons that can be accommodated in the next shell i.e. L shell, using the same formula. Thus, the electron carrying capacity of the L shell = 2n2 = 2(2)2 = 8 Therefore, we can house 8 electrons in the L shell of an atom. One important rule for the positioning of atoms must be mentioned at this stage. For any shell containing more than 4 electrons, the electrons are accommodated in the shell in a group of 4, in a clockwise manner. This means that the first four electrons are located at an angle of 90° from each other and this angle keeps on decreasing as the number of electrons increases. However, in the case of the Beryllium atom, we are only left with 2 electrons for the L shell. Hence, the number of electrons in the L shell of the Beryllium atom = 2 These electrons will be positioned at an angle of 90° from each other.
Hence, the Bohr model of the Beryllium atom consists of 4 protons, 4 electrons, and 5 neutrons. Out of the 4 electrons, 2 are accommodated in the K shell while the remaining 2 are housed in the L shell of the Beryllium atom.
Deriving Lewis Structure from Bohr Model
The Lewis structure of the atom also pictorially represents the structure of an atom. However, unlike the Bohr model, it only illustrates the valence electrons. The nucleus of an atom is represented by the atomic symbol while the electrons are represented using the dots. Therefore, this model is also known as the electron dot structure. As discussed in the previous section, the Beryllium atom contains 2 valence electrons and the atomic symbol of Beryllium is Be. Therefore, the Lewis structure of Beryllium can be drawn as:
Properties of Beryllium
A few important properties of Beryllium are: • It was discovered by French chemist Nicolas-Louis Vauquelin. • It is white-gray metallic in appearance. • The melting and boiling points of Beryllium are 1560 K and 2742 K, respectively. • The density of Beryllium is 1.85 g/cm3 at room temperature and 1.69 g/cm3 at melting point. • Naturally, three isotopes of Beryllium are known to occur. They are 7Be, 9Be, and 10Be.
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Conclusion
The Bohr model of Beryllium consists of 4 protons and 5 neutrons in its nucleus, while 4 electrons revolve around the nucleus. The number of protons, as well as the number of electrons in an atom, is always equal to its atomic number. The number of neutrons in an atom is calculated using the formula: The number of neutrons = Number obtained by rounding atomic mass of the atom up to the nearest whole number – Number of protons in the atom. The electron carrying capacity of an atom is calculated by using the formula 2n2. In the Beryllium atom, 2 electrons are housed in the K shell and the remaining 2 electrons in the L shell.
