At the end of the article, you will able to Describe the Structure of an Atom and Basic Structure. It was around the first decade of the 19th century, a chemist and a physicist from England named John Dalton was successful in answering many questions. He proposed a theory which was then known as Dalton’s atomic theory.
With this theory many concepts regarding the matter, the composition of matter, atoms, and even combinations of atoms resulting in compounds better understood. Let’s first take a very quick look at the few major postulates of his theory.
- He said that all matter is made up of very tiny particles called atoms.
- Secondly, he suggested that atoms are indivisible particles which cannot be created or destroyed in a chemical reaction.
- The third postulate was atoms of a given element are identical in mass and chemical properties.
- Similarly, the fourth postulate was that atoms of different elements have different masses and chemical properties.
- The fifth postulate stated that atoms combine in a ratio of small whole numbers to form compounds.
- Lastly, the relative number and kinds of atoms are constant in a given compound
I know I just rattled off the postulates. Don’t worry that was the little bit history of the atom which tells what scientists thought at that time about the atom. Let’s understand the structure of an atom.
Must Read –
- What is Matter?
- History and Properties of Atom.
- What is atomic Structure -Definition?
- What are the Subatomic Particles of Atom?
Basic Structure of an Atom
The basic structure has explained below:
- The atom is made of smaller particles. These smaller particles are known as subatomic particles.
- The three subatomic particles are electron, proton, and neutron.
- An electron is having a negative charge, a proton has a charge of positive while neutron has no charge.
- The entire mass is in the nucleus as proton and neutrons are present in a small nucleus at the centre.
- The electrons revolve around the nucleus. They have a very small mass.
- The nucleus is having a positive charge because of the presence of protons at the center.
- The electrons revolve around the nucleus at a very high speed in a fixed circular shell known as energy level or shell.
- An atom on a whole is electrically neutral it is because the number of electrons outside the nucleus is equal to the number of the proton inside the nucleus. Therefore, an atom on a whole has no positive or negative charge. So, Atom is electrically neutral.
Describe the Structure of an Atom
Although no one has yet found a way of getting a close-up view of an atom. Different experiments have made it possible to build up a picture or model of what atoms consist of. The colours in these models are of course used simply to distinguish between different particles.
- In the centre of an atom is a nucleus. This is made up of even smaller or subatomic particles called protons and neutrons. The protons each carry a positive electrical charge, the neutrons are as heavy as protons but carry no charge. This means that overall the nucleus is positively charged.
- Orbiting around the nucleus is a negatively charged particles called electrons. The size of the negative charge carried by an electron is equal to the positive charge carried by a proton. The electrons are moving at incredible speed in fact three-quarters of the speed of light
Structure of an Atom
- The number of protons distinguishes the atom of one element from atoms of another element
- The atoms of the same element are the Identical in all respects, size, size, and mass.
- Atoms of various elements combine with a certain ratio to form a compound which is term as molecules.
- The atomic number of an element does not change during a chemical reaction.
- Proton and the neutrons have unit mass each, the atomic mass is numerically equal to the sum of proton and neutron.
- The atomic number of an element is donated by the letter Z.
- The atomic number tells us the number of proton in an atom of an element.
- It also tells the number of electrons in a normal atom.
- An electron has negligible mass and they have almost no contribution towards the weight of an atom. However, the volume is mainly due to this part.
- The mass number is donated by the letter A.
- Hence, the mass number is the number of its nucleons.
Mass number = No. of protons + No. of neutrons.
Atomic Number and Mass Number
- In 92U238, atomic number, Z = 92 and mass number, A = 238.
- In 8O16, atomic number, Z = 8 and mass number, A =16.
This is all about the article Describe the Structure of an Atom and its Basic Structure.