BASIC STRUCTURE OF AN ATOM FOR KIDS
Atoms are the basic building block of matter. There are 118 different kinds of atoms. These atoms make 118 kinds of basic substances, elements. They are the smallest particles, which has all the features and properties of that particular element. Although atom is the smallest block it is not like that that we can’t break it. Yes, you read it right. Atoms are not the tiniest particles of all. We can break an atom into smaller pieces, called subatomic particles – electrons, protons, and neutrons. However, it is important to note that if we break an atom then all features of that particular element are lost. As an atom consists of subatomic particles, so in this post, we will study – the basic structure of an atom.
DISCOVERY OF SUBATOMIC PARTICLES
For a long period in history, scientists were of opinion that atoms could not be broken further into the smaller particles. But things changed after the discovery made by a scientist named J.J. Thomson in the year 1897. In his quest to ascertain the basic structure of an atom, he discovered that atoms are divisible and contain a negatively charged subatomic particles – ‘electrons’.
Soon, after J.J. Thomson discovery, the race began among other scientists to uncover the basic structure of an atom.
- Goldstein in the year 1898, concluded that – since all atoms are electrically neutral thus, there must be positively charged particles present in them. He named these particles – ‘protons’.
- Rutherford in the year 1911, stated that all the positive charged particles join together to form a ‘nucleus’. This nucleus is present at the center of an atom and all electrons revolve around it.
- James Chadwick in the year 1932, studied the atomic model and concluded that – in the nucleus of the atom are present, particles which have no charge but mass almost equal to that of the proton. This led to the discovery of – ‘neutron’.
To know more about the discovery of subatomic particles, click here
BASIC STRUCTURE OF AN ATOM
An atom has a central part called the nucleus. This contains the subatomic particles named protons and neutrons. Each proton has an electrical charge, almost like a tiny battery, but no both positive and negative – only positive. Neutrons are the same size as protons but they have no electrical charge. Neutrons help in keeping protons together. Electrons are much smaller than protons and neutrons. They are not present in the nucleus. They whizz around it, in imaginary layers known as orbits or shells. Electrons in the outer shells have more energy than those in the inner shells. Each electron also has an electric charge, which is negative – opposite to the charge of a proton.
Electrons revolve around the nucleus at speed approximately 3/4th of the speed of light. So, a question arises what stop them from shooting out of an atom? The answer is – a force of attraction between negative and positive charges prevent electrons from escaping. The positively charged protons present in the nucleus attract negatively charged electrons with a force, called the electrical force of attraction. Amount of positive charge on a proton is exactly equal to the amount of negative charge on an electron. Usually, an atom has the same number of protons and electrons. So, the positives and negatives are equal, which means the whole atom has no electrical charge.
The basic structure of an atom of elements differs from each other in respect to the number of protons and electrons it contains. For example, the smallest atom of hydrogen contains only one proton, one electron, and no neutron. Whereas largest known atom of Ununoctium (also known as Oganesson) posses 118 protons, 118 electrons and approximately 176 neutrons in it.
To understand the basic structure of an atom, good knowledge of electron shells is very important. Electrons revolve around the nucleus at a fixed distance from it. An electron shell is a path followed by electrons during the revolution. Nucleus due to the presence of protons tries to pull electrons toward it. In order to avoid fall into the nucleus, electrons revolve at very high speed. Electrons with low speed or energy revolve closer to the nucleus in comparison to those with high energy levels.
Wonderful video showing the basic structure of an atom. Courtesy St. Mary’s Physics Online
The existence of electron Shells was first brought out by Charles Brakla. He stated there are 7 numbers of electron shells and labeled them with letters K, L, M, N, O, P and Q. They are also labeled as 1, 2, 3, 4, 5, 6, and 7 going from innermost shell to outwards. The closest shell to the nucleus is ‘1-shell’ or ‘K-shell‘, next comes ‘2-shell‘ or ‘L-shell‘ and so on. The farthest shell from the nucleus is ‘7-shell’ or ‘Q-shell’.
Each type of shell can contain only a fixed number of electrons. This number can be determined using formula 2n². Here ‘n’ stands for the numeric label of the shell. From the formula, the maximum number of electrons in shell K is 2, L is 8, M is 16, N is 32, O is 50, P is 72 and Q is 98.
Although, the formula gives the maximum in principle, in fact, that maximum is only achieved for the first four shells (K, L, M, N). No known element has more than 32 electrons in any one shell. This is because of the presence of subshells. Each electron shell consists of subshells or orbitals. The number of subshells a shell can contain depend upon its level. Therefore, shell-K consists of 1 subshell, shell-L consists of 2 subshells and so on.
To know more about electron shells, click here
FUNDAMENTAL OR ELEMENTARY PARTICLES
For a long time in history, atoms were believed as fundamental or elementary particles of the Universe. However, this belief changed after unraveling of the basic structure of an atom and discovery of subatomic particles – electrons, protons, and neutrons. Now with advances in science, we now know that there are many other subatomic particles besides electrons, protons, and neutrons. They include muons, gluons, gravitons and dozens of others. And even particles protons and neutrons are not the smallest of all. They are made of even tinier pieces – quarks. There are six kinds of quarks, with the odd names of up, dons, strange, charmed, bottom and down quark. Quarks, along with a group of particles called leptons, which includes electrons, are probably the smallest pieces of matter. They might be fundamental or elementary particles.
To know more about fundamental or elementary particles, click here
What we learned above was very basic about the structure of an atom. Keep following for related posts.