Atomic Structure Flashcards
The evolution of the atomic structure
Who came up with the name ‘atom’ and how?
Democritus, a Greek philosopher. He said that there are various elements from which matter are made, and if you keep cutting a sample of matter, you will arrive at an ‘uncuttable’ unit which he called an atom.
State John Dalton’s atomic theory.
- Everything is composed of atoms, which are the indivisible building blocks of matter and cannot be destroyed. (C - Composition)
- All atoms of an element are identical. (I - Identical)
- The atoms of different elements vary in size and mass. (S - Size)
- A chemical reaction results in the rearrangement of atoms in the reactant and product compounds. (A - Arrangements)
- Compounds are produced through different whole-number combinations of atoms. (W - Whole Number)
What laws did Dalton’s atomic theory explain?
The law of definite proportions
The law of multiple proportions
Who proposed the idea of isotopes?
Frederick Soddy, 1912
Who discovered that atoms have an electrical component?
Michael Faraday, 1830’s
What particle did JJ Thompson discover?
Electrons
Who discovered cathode rays?
William Crookes, 1879
Who came up with the plum pudding model?
JJ Thompson
Who discovered neutrons?
James Chadwick, 1932
Who discovered the mass of an electron?
Robert Milikan, 1916
What is the mass of an electron?
9.11 x 10^-28 g
How were atomic numbers assigned?
They are assigned to elements based on the frequency of the x-rays they emit when used as the anode of an x-ray tube. It was used to determine the number of protons in the nucleus.
State Heisenberg’s Uncertainty Principle
If we measure the momentum of an electron accurately, we cannot know its position with certainty.
How are the physical and chemical properties of isotopes?
Isotopes may have different physical properties but the same chemical properties. This is is because neutrons only contribute to the mass of an atom, not its chemical behaviour.
