Discovery of Atoms

Introduction

The structure of matter and the existence of atoms have long been a source of speculation. The ancient Greeks, particularly the philosophers Leucippus & Democritus, are responsible for some of the oldest essential concepts that have survived. They considered if a substance might be separated into smaller and smaller parts indefinitely. One is the possibility of an infinitely small subdivision. Another is Democritus’ belief that a minimal unit cannot be subdivided anymore. We now know that atoms may be separated but that the process destroys their identity. Another reasonable belief held by the Greeks was that atoms were constantly moving.

The Greeks and others hypothesised about the discovery of atoms’ qualities, claiming that there were only a few types and that all matter was made up of diverse combinations of these types. Rather than the basic components, the Greeks selected the most typical examples of the four states of matter (solid, gas, plasma, and liquid). It took more than 2000 years for equipment capable of exposing the real nature of atoms to be developed.

Alpha Particles and the Atom

In 1911, Ernest Rutherford discovered the atom’s nucleus. In that sense, an atom cannot be seen. 

What exactly are alpha particles, and what are their functions?

Two protons & two neutrons are tightly linked together to form alpha particles (). They are emitted from the nucleus of specific radionuclides during alpha decay, a kind of radioactive decay. The nucleus of a typical helium atom, i.e., a doubly ionised helium atom, is identical to an alpha particle.

What characteristics do alpha particles have?

Compared to other nuclear radiation types, alpha particles are slow and hefty. The particles have a mass of around 4 protons and travel at 5 to 7% of the speed of light or 20,000,000 metres per second.

Alpha particles cannot penetrate very far through matter due to their strong ionisation and are brought to a halt by a few centimetres of air or less than a tenth of a millimetre of biological tissue.

What are some of the applications for alpha particles?

• Although alpha particles have a modest penetrating strength, they can nevertheless be used for a variety of applications:
• Ionising smoke detectors — americium-241 is widely utilised in these devices. Smoke entering the sensor decreases the number of alpha particles detected, causing the alert to sound.
• To eliminate static charges from equipment, static eliminators commonly utilise alpha particles from polonium-210.
• Radioisotope thermoelectric generators, often employed in space probes, utilise alpha particle decay from plutonium-238 to generate heat, which is then converted to power.
• Some alpha emitters are now being studied for their possible use in cancer treatment using unsealed source irradiation.

Atoms:

A chemical element is made up of atoms, which are the tiniest units of ordinary matter. The Discovery of atoms that are neutral or ionised makes up every matter. Atoms are extremely small, with a diameter of roughly 100 picometers. 

The Discovery of atoms comprises a nucleus or one or even more electrons attached to it. One or more protons and several neutrons make up the nucleus. Only one form of hydrogen, which is the most common, is devoid of neutrons. The nucleus accounts for more than 99.94 % of the mass of an atom. The protons carry a positive electric charge, whereas the electrons have a negative charge, and the neutrons have none. If several electrons and protons in an atom are equal, it is electrically neutral. Ions are atoms that have a negative or positive total charge due to the presence of more or fewer electrons than protons.

Atomic nucleus

Rutherford, who discovered the nucleus of an atom, the nucleus is the centre of the universe.

The nucleus h is the most central part of the atom. Protons and neutrons are the two subatomic particles that make up the nucleus.

Structure of the Atom

Atoms are the fundamental constituents of all substances. Atoms make everything that you can see, feel, and touch. Even things that you can’t see, feel, hear, or touch are made up of atoms.

Numbers of Atoms

• The atomic nucleus is located in the atom’s centre. The number of neutrons and protons in an atom determines the atom’s type or element. A group of atoms with the same atomic structure is referred to as an element. Hydrogen, for example, is an element.
• The atomic nucleus’s composition reveals a great deal about the element it symbolises. The atomic number is related to the number of protons inside the nucleus. Protons have a positive charge (+). The electrons (-) must balance the atom’s negative charge to have a neutral charge. As a result, there are exactly as many protons as electrons in a neutral atom. So, if you know the atomic number and the charge of the atom, you can easily calculate the number of electrons. 

What role do neutrons play in all of this?

• Neutrons Are neutral & protons are positively charged.
• Even though neutrons do not provide the atom any charge, they are significant in the atomic structure. The neutron is the biggest particle in the subatomic world. Protons and neutrons are added together to obtain the atomic mass. Because electrons are so tiny, their mass only accounts for—0.1 per cent of the total mass. The electrons aren’t inside the nucleus; instead, they’re whizzing around on the nucleus’s periphery.
• We can find out the number of neutrons by deducting the atomic number from the atomic mass because the atomic number tells us the number of protons in an atom. The atomic mass gives us protons and neutrons.

Conclusion:

Atoms are the fundamental constituents of all substances. The contemporary atomic theory describes the notions of atoms and also how they interact with one another to form matter. Atoms are made up of negatively charged electrons orbiting a core nucleus made up of more massive positively charged protons & electrically neutral neutrons, which display the properties of the element. The release of energetic particles & rays by some substances is known as radioactivity. Helium nuclei, high-speed electrons, and rays are three essential types of radiation.