Skip to main content

Atoms

Atom

Atoms are the building blocks of matter also known as the smallest unit of matter. The word atom comes from a Greek word meaning invisible. An atom is the smallest particle of the element which can take part in a chemical reaction. The parts of the periodic table are known as elements. It is made up of subatomic particles which are the electron, neutron & proton.

History of Atom

In the Past

  • Long back in India around 500bc an Indian philosopher Maharishi Kanad, explained that if we divide matter, we will get smaller and smaller particles.
  • Ultimately, a time will come will when we shall come to the smallest particle and further division would not be possible. He named these particles as ‘parmanu’.
  • TheIndian philosopher Pakundha Katyayama went a step further and proposed that the particles of matter i.e. parmanu normally exist in a combined form.
  • He also said that the combinations of particles give us various kind of matter.
  • Ancient Greek philosophers Democritus and Leucippus also explained the same theory and called these particles ‘Atom’ meaning invisible.

Dalton's Atomic Theory

John Dalton was born in England 1766 to a poor weaver’s family. He got his early education from his father and village school. He started teaching in the village at the age of 12. Dalton left for Manchester to teach physics, chemistry, and maths in a college in 1793. On 1808, Dalton presented his atomic theory to explain the properties of matter and atoms. 
His theory stated the following:
  • All the matter is made up of very small particles called ‘atoms’.
  • Atoms can neither be created nor destroyed.
  • Atoms cannot be divided.
  • All atoms of a particular element are same in every respect. They have the same mass, size, and chemical properties.
  • Atoms of different elements have different mass, size, and chemical properties.
  • Chemical combinations of atoms form molecules of compounds.
  • The number and kind of atoms in a compound are fixed.
  • Atoms of the same element can combine in more than one ration to form more than one compound.
  • The Dalton theory is based on-
  1. Law of conservation of mass as it states ‘atoms can neither be created nor destroyed’.
  2. Law of constant proportion as it states ‘the number and kind of atoms in a compound is fixed’.

Drawbacks of Dalton's Atomic Theory
  • Dalton’s theory included that atoms couldn’t be divided but under special, atoms can be further divided into smaller particles called electrons, protons, and neutrons.
  • His theory says that all atoms of an element have exactly same mass but atoms of the same element have slightly different masses.
  • His theory also explained that atoms of different elements can have the same mass.

Enjoy your high school with - High School Pedia : www.highschoolpedia.com


Comments

Popular Posts

Isotopes, Isobars and Isotones

Isotopes These are elements which have the same atomic number but different atomic mass . They have the same atomic number because the number of protons that are inside their nuclei remains the same. But, they have different atomic mass because the number of neutrons that are also inside their nuclei is different. As the number of protons inside nuclei remains same, therefore the overall charge of the elements also remains same as in isotopes: no of protons = no of electrons . Hence, as isotopes overall charge remains neutral, therefore their chemical properties will also remain identical.   Therefore, Isotopes are chemically same but physically different.

Anode Ray Experiment

→Anode ray experiment was conducted by E Goldstein. →These rays are also known as canal rays. →This experiment helped in the discovery of the proton. Apparatus Used A discharge tube  was taken in which there were 2 electrodes i.e. Anode(+ve) and the cathode (-ve). The tube was filled with an inert gas. A perforated or porous cathode was used. A layer of zinc sulphide was placed at the back of the cathode. There was a vacuum pump in the tube. High voltage (5000v-10000v) was allowed to flow through the system. It was observed that when the gas was at 1atm(atmospheric pressure ) no change was seen in the tube.  When the   pressure   was decreased inside the tube, a glow could be seen at the back side of the cathode.

Android Versions Named After Sweet

Have you ever thought why are Android versions always named after sweet names ?? Everytime a new Android version is launched its name is kept after a sweet name. Many people have researched about this topic and many have asked Google also. Have you ever tried to find out the core reason behind this? If not then you would find the answer here . First of all let us first see what Google says about this : In 2008 i.e. the year when Android was launched a reporter asked the reason for the same. At that time Google said “It’s kind of like an internal team thing, and we prefer to be a little bit — how should I say — a bit inscrutable in the matter, I’ll say,” said Randall Sarafa, a Google spokesman. “The obvious thing is that, yeah, the Android platform releases, they go by dessert names and by alphabetical order for the most part."

Rutherford Alpha Ray Scattering Experiment

Rutherford Alpha Ray Scattering Experiment Hey, Guys, most of you might have heard about the alpha ray scattering experiment and if you want to know in detail about Rutherford's model and the experiment he conducted, this is the right place for you... But first: Things You Must Know Some basic information that will help you understand rutherford experiment properly: Proton is a sub-atomic particle which is positively charged and has a mass of 1u. Alpha particles are helium atom with a charge of +2 as they have lost 2 electrons. Alpha particles have an atomic mass  of 4u. Gold is highly malleable and can be beaten into very thin sheets. Experiment Rutherford conducted his experiment in the following way: Rutherford took a very thin gold foil and bombarded it with high energy alpha particles. He placed a layer of zinc sulphide on the walls where the experiment was taking place because when alpha particles strike zinc sulphide layer, it results i

Cathode Ray Experiment

This experiment was conducted by J.J. Thomson (Sir Joseph John Thomson) in the year 1897. This experiment proved that atom is made up of fundamental particles which are much smaller than the smallest atom 'hydrogen' This experiment helped to discover electron. According to J.J. Thomson, the cathode rays consisted of very light, small and negatively charged particles. He named the particles "corpuscles" which were later known as electrons

Pokemon Go 0.33.0

All Pokemon go fans get ready because again the latest version of Pokemon go is out. The Niantic has released a new version of Pokemon go i.e. 0.33.0.The size of the new version is 61.48MB.

Lets talk STARS

Hey guys, have you ever spent any of your nights at the uncovered top floor or backyard of your house. If you have then this article will help know about all the things, you just observed out there in the space or even if you did not have this article will help you observe and understand all the miracles that happen in that huge space above us. In this one, we will talk about STARS- STARS There are about 6k-10k stars that a person with a normal eyesight can observe in that huge space.(well that number varies according to your eyesight) You might have observed or will observe that the stars in the space are not all the same in brightness and color. Well, the brightness of a star depends on the combination of 2 reasons.   The ACTUAL BRIGHTNESS -   Actual brightness of a star refers to the magnitude of real brightness that, that particular star have.You can think of that as energy.Different stars have different levels of energy(brightness).The star with more energy w