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How Do Atoms Exist?

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  • Difficulty Level : Expert
  • Last Updated : 06 Aug, 2021

If you are going to build a house, you will undoubtedly need to manage a big number of bricks. This is due to the fact that it may be classified as a building component for your well-planned shelter. Similarly, atoms are the basic building units of stuff that surrounds us. Think of anything, and it will undoubtedly be made of atoms! Isn’t it crazy? Let us try to comprehend this notion thoroughly in order to acquire a clear understanding of their existence and what an atom is.

What is an Atom?

The word “atom” comes from the Greek “atomos”, which simply means indivisible. Everything on our earth is a combo of stable and unstable elements. Each element has a different atomic structure. The basic structure of an atom involves a nucleus and orbiting electrons.

An atom is the tiniest quantity of a chemical element that may exist. For example, one atom of gold is the lowest amount of gold that may possibly exist. The term “small” actually refers to nanoscopically small! A human hair is hundreds of times smaller than an atom.

Atoms and Molecules exist in nature due to the fact that matter is made up of small particles called atoms. However, in ancient times there was no clue to the scientists therefore at that time Indian Philosophers believed that everything in this universe either living or non-living can be divided into ‘panch tattvas i.e. Air, Water, Fire, Sky, and Earth.

In other words, we can say that Atoms are the fundamental building units of all stuff. The result of which is that you can’t see an atom with your naked eyes instead you will require an electron microscope to be able to view that. If you dismantle a range of objects, you’ll discover that all matter in our environment is made up of various types of atoms. We as Living organisms are normally made up of hydrogen, carbon, and oxygen atoms.

Parts of An Atom

An atom consists of three parts namely Protons, Electrons, and neutrons. In the center of an atom, neutrons and protons are bound together. The nucleus is the name for that area. Electrons, on the other hand, which are much smaller, speed around the outside.

1. Electrons

Electrons are negatively charged and are arranged around the nucleus in shells or orbits. They have a relative charge of -1. The total number of electrons in an atom is always the same as the number of protons in the nucleus.

Characteristics of Electrons:

  • The charge of an electron is -1e, which approximates to -1.602 × 10-19.
  • The mass of an electron is approximately 9.1 × 10-31.
  • Due to the negligible mass of electrons, they are ignored when calculating the mass of an atom.

2. Protons

Protons are always positively charged. The number of protons in the atom is called its atomic number(also called proton number). In the Periodic Table, atoms are arranged in atomic number order. Protons have a relative charge of +1.

Characteristics of Proton:

  • Protons are basically positively charged particles of an atom. The charge of a proton is 1e, which corresponds to approximately 1.602 × 10-19.
  • The total number of protons in the atoms of an element is always equal to the atomic number of the element.
  • The mass of a proton is approximately 1.672 × 10-24.
  • It has been observed that Protons are over 1800 times heavier than electrons.

3. Neutron

Neutrons have a neutral charge neither positive and nor negative. Neutron, a neutral subatomic particle found in all atomic nuclei except common hydrogen. Neutrons and protons, together known as nucleons, are held together in the compact inner core of an atom, the nucleus, where they account for 99.9% of the atom’s mass.

Characteristics of Neutron:

  • The mass of a neutron is almost the same as that of a proton i.e. 1.674 × 10-24.
  • Neutrons are electrically neutral particles and carry no charge.
  • Different isotopes of an element have the same number of protons but vary in the number of neutrons present in their respective nuclei.

4. Nucleus

It is the center of the atom. It consists of protons and neutrons. The nucleus diameter is only about 1/100000 of the atom’s diameter, so much of the volume of the atom consists of empty space. When people draw atomic structures, electrons are shown spinning in orbits around the nucleus. To be more specific, electrons travel so swiftly that you never know where they are at any given time.

5. Electron cloud

It is the outer portion of the atom. An electron cloud is an area of negative charge that surrounds an atomic nucleus and is linked to an atomic orbital. It is theoretically defined, and it describes an area having a high chance of harboring electrons.

Note: The number of protons and electrons in an atom remains constant. Furthermore, the number of neutrons is nearly equal to the number of protons, but this is a rare occurrence.

The phrase atomic number refers to the number of protons contained in an atom. The atomic number 1 indicates that the atom is hydrogen. Likewise, atomic number 2 shows a helium atom. The relative atomic mass is calculated by adding the total amount of neutrons and protons. Hydrogen, for example, has a relative atomic mass of one, but helium has a relative atomic mass of four. To put it another way, a helium atom is four times denser than a hydrogen atom

How To Know If Atoms Exist?

Now, you might be thinking How did we know atoms existed if we couldn’t see the atoms? As we know Science is known for providing evidence to support each of its theories. As a result, evidence for the existence of atoms comes in a number of formats. Large atoms have been intentionally broken into smaller copies by scientists. There are various theories which support the point that atom exists in nature. Some of the theories are listed below:

1. Dalton’s Atomic Theory

Dalton gave his atomic theory in the year 1808. Dalton was the first person to give a complete theory to describe all matter in terms of atoms and their properties. The whole theory of Dalton is based on the law of conservation of mass and the law of constant composition. The postulates of Dalton’s theory may be stated as follows:

  • The first postulate states that “All matter is composed of atoms, which are indivisible.”
  • The second postulate states that “All atoms of a given element are identical in mass and properties.”
  • The third postulate states that “Compounds are combinations of two or more different types of atoms.”
  • The last postulate states that Chemical reaction is basically a misplacement of atoms.”

However, Dalton’s theory got some drawbacks after the discovery of subatomic particles and isotopes

2. Thomson’s Plum Pudding Model

Thomson regarded atoms as a positively charged sphere, where electrons are embedded like plums in a pudding. This model is also similar to a watermelon. Thompson Cannot explain how positive and negative particles could be shielded from each other without getting neutralized inside the atom.

3. Rutherford’s model and Discovery of the Nucleus 

Ernest Rutherford headed a team that fired particles at atoms and carefully examined them, based on a popular set of experiments from the early twentieth century. It demonstrated how the orbits in the interior of a normal atom were structured. The postulates of Rutherford’s Model may be stated as follows:

  • The volume occupied by an atom is mostly empty space
  • The nucleus is inside the atom and has a positive charge
  • The size of the nucleus is small compared to the total volume of the atom
  • The electrons revolve at high speed around the nucleus

The drawback of Rutherford’s model is that, if the electron continuously moves around the nucleus, it will lose energy and will fall into the nucleus. But the atom is one of the most stable structures known. This stability could not be explained by Rutherford’s model

4. Bohr’s Atomic Model

According to Bohr’s Atomic Model, Electrons revolve in fixed orbits around the nucleus. An electron cannot lose or gain energy as long as it is in its own orbit. If it gains energy, it moves to a higher orbit and if it loses energy, it moves to a lower energy level. The model basically removes all the drawbacks of Rutherford’s Model and Explained the stability of the atom.

Sample Problems

Problem 1: Name two atoms that exist as independent atoms.

Solution: 

Noble gases such as argon (Ar), helium (He) exist as independent atoms.

Problem 2: Why is it not possible to see an atom with naked eyes?

Solution: 

Because an atom is too small, i.e., the atomic radii of an atom is of the order 10−10 m to 10−9 m.

Problem 3: What is meant by the term chemical formula?

Solution: 

The chemical formula of a compound is a symbolic representation of its composition and actual number of atoms in one molecule of a pure substance.

Problem 4: In how many forms does an atom exist usually?

Solution: 

Generally an atoms exist in the following two forms:

  • In the form of molecules
  • In the form of ions

Problem 5: What is the total number of charged particles in an atom?

Solution: 

The charged particles contained in an atom are protons and electrons


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