Structure of an Atom


Structure of an Atom

By Jisha Jamal

Kiwi fruits are a treat to our taste buds, but have you ever noticed their inner portion? It has a light-coloured center and surrounding layers of black seeds located within the fruit flesh.

If we compare an atom with a Kiwi fruit, the concentrated center portion can be compared to the positively charged atomic nucleus and the black colour seeds to the negatively charged electrons. It was believed that these electrons revolve around the nucleus as the earth and the other planets revolve around the sun. As we know, the atom is the smallest particle of an element and none can see the movement of these electrons with the naked eye. The nucleus has two types of sub-atomic particles, the positively charged protons and the neutral neutrons The above-given concept of a mature nucleus and obedient electrons that maintain a regular and normal path was proposed by the Danish scientist Niels Bohr.

In 1922, Bohr received a Nobel prize for proposing this atomic structure that laid the foundation for quantum physics. But do you think, the passive and obedient electrons and silent nucleus can generate radioactivity? They will live together happily thereafter, don’t they? But the reality is the tremendous energy of radioactivity. The mighty alpha rays, beta rays, gamma rays, X rays and ever-moving quarks and neutrinos are the truth.

What contributes to these invincible phenomena? When Bohr’s atomic structure could not explain these phenomena, scientists came up with several ideas including electrons moving in the same circular orbits but in different directions. Among them, Louis De Broglie borrowed Einstein’s wave theory of light and explained that all forms of matter like protons, electrons, atoms, and molecules show dual characters like light. de Broglie, by using Maxwell’s electromagnetic wave theory formulated the concept of matter waves. Matter waves are waves associated with moving microscopic particles.

Let’s go back to the Kiwi fruit to understand the concept. In the image, you must have seen the tender flesh spread around the black seeds. Imagine, these tender layers are the path of those seeds that move in and around and the tender layers are formed because of the movement of those seeds. Instead of forming a round path, the path formed by the seeds is like waves. Similar is the case with the path of electrons around the nucleus. These paths of electrons around the nucleus are called orbitals. Orbitals are regions in space around the nucleus where electrons are likely to be found.

Now, let’s understand why scientists were worried about the structure of atoms in terms of radioactivity. What is radioactivity? Radioactivity is the emission of radiation or particles caused by the disintegration of the atomic nucleus. Alpha particles are positively charged particles that consist of two protons and two neutrons.

Beta particles are negatively charged and are generated by the nucleus during its disintegration process, whereas gamma rays are neutral radiation. If the Bohr Atom model was correct, an atom always will have a stable nucleus with the same number of protons survived by the same number of obedient electrons moving around it at a desirable velocity.

The disintegration of the nucleus indicated the possibility of charge difference and growing tension within the nucleus. The primary reason could be the mismatch in the charge and that led to the discovery of the wave theory of sub-atomic particles. This concept led Werner Karl Heisenberg to formulate a principle about the location of electrons within the atomic orbitals named Heisenberg’s uncertainty principle.

Heisenberg stated that “It is not possible to determine simultaneously and precisely both the position and momentum of a microscopic moving particle like an electron, proton etc.” According to the uncertainty principle, due to the wave nature of the electron, we cannot describe the exact path i.e., the position followed by an electron at any time. Thus Bohr’s theory, according to which electrons are regarded as having a fixed position of definite energy, is no longer correct.

How does it affect human beings if we believe that the Bohr Model of an atom is the correct model and shut all further research based on wave theory? If the scientists did not explore the truth behind the atomic structure,

  1. We would never have been able to treat cancer patients

Gamma rays are used to kill off cancer cells and are used for cancer treatment. The atom of the element Cobalt-60 is commonly used for this purpose. Utilizing radiation to combat cancer is an important career. With the growing rate of cancer cases in the world, a degree in radiation therapy reckons a lot of opportunities.

  1. Killing Microbes

Gamma rays are successfully used to destroy microbes that cause food to decay. Surgical instruments and syringes can also be treated with gamma rays. It is a great way to prevent infections been transferred.

  1. Carbon Dating

When an animal or plant dies it stops taking in carbon. But its carbon-14 content continues to decay. If we compare carbon-14 with that from a living thing, the age of animal and plant remains can be calculated. This is known as carbon dating. Carbon dating is used in the study of fossils. It is also a great career that has opportunities in the disciplines of archaeology, paleontology etc,

  1. Calculating the age of rocks

1.2% of the remaining potassium atoms are radioactive, known as K-40. The nucleus of this atom disintegrates for twelve thousand years and eventually decays to form the stable argon atom. By tracing the argon content of potassium rocks, scientists can calculate the age of such rocks. Therefore, it is great to support geologists and geographers.

Learning Chemistry in general and about atoms and molecules in particular with an eye for details is a great achievement. So, I suggest all of you read and understand it.

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