CHAPTER ONE

My favourite subject is chemistry. Especially atomic structure. So what is an Atom? Atoms are the basic (atoms are made up of subatomic particles.) unit of matter. And matter is something that has mass and occupies space. Atoms are made up of subatomic particles (and other tinier particles-which isn’t that important) which are grouped into two major parts:

  • The Nucleus- it contains Protons which are positively charged and Neutrons which are neutral in charge. (those extra particles are in here too.)
  • Shells- or orbits are the path in which the third major part, Electron which contains negative charge, revolve around the nucleus, like planets revolving around the Sun.
The Basic Structure Of an Atom
The Basic Structure Of an Atom

Think: IF THE NUCLEUS CONTAINS POSITIVE CHARGED PARTICLES ONLY WHY DON’T THEY REPEL (like charges repel)  AND WHY DOESN’T THE ATOM SPLIT (OR DISINTEGRATE)?

ANSWER: The neutrons in an atom acts like nuclear cement. it holds the protons together even if they try to repel.


For Characteristics of Fundamental Particles click here .docx



Four different scientists produced their own ideas of the atoms’ structure. 

  • John Dalton
  • JJ Thompson
  • Ernest Rutherford
  • Neils Bohr

John Dalton
The Postulates of Dalton

  • All matter is made of indivisible and indestructible atoms which are very tiny. (partially correct, they are tiny but yet divisible-discovery of subatomic particles.)
  • All atoms of a given element are identical in their physical and chemical properties. (was later proven wrong, due to discovery of Isotopes)
  • Atoms of different elements differ in their physical and chemical properties.(was later proven wrong, due to the discovery of isobars)
  • Atoms of different elements combine in simple whole number ratios to form compounds(later proven wrong, since they can combine in fractions.)
  • Chemical reactions consist of the combination, separation, or rearrangement of atoms.

JJ Thompson

As per his plum pudding model (there many names for this atomic model), Negatively charged particles are embedded in a Positive sphere.


Later proved wrong since this way electrons would fuse with the positive and the atom would cease to  be.


This way the Universe would collapse.


Ernest Rutherford

He conducted ‘the gold foil experiment’



Atomic Model of Rutherford is available in detail in next chapter.


ARYAMAN

any doubt – feel free to ask in the comment box


FOR MORE KNOWLEDGE VIEW CHAPTER TWO OF ‘ATOMIC STRUCTURE’

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