ATOMIC THEORY Flashcards
stated that matter is composed on tiny indivisible particles called atoms
Democritus
English school teacher who performed experiments to learn in what ratios different elements combine in chemical reactions
John Dalton
Dalton’s Atomic Theory
- All elements are composed of submicroscopic particles called atoms.
- Atoms of the same element are identical.
- Atoms of different elements can physically or chemically combine.
- Chemical reaction occurs when atoms are separated, joined, or rearranged
English physicist who discovered electrons in 1897 and proposed the model “plum pudding”
Sir JJ Thomson
discovered the positively charged subatomic particles called protons
E. Goldstein
English physicist who confirmed in 1932 the existence of another subatomic particle: neutron
Sir James Chadwick
based on his discovery of the nucleus, he proposed the “Nuclear Atomic Model” in which electrons surround a dense nucleus
Ernest Rutherford
young Danish physicist and a student of Rutherford proposed that the electrons are arranged in a concentric circular path, or orbits around the nucleus (Planetary Model)
Neils Bohr
Austrian physicist proposed the “Quantum Mechanical Model” that shows the probability of finding electrons within a certain volume of space portrayed in a cloud
Erwin Schrodinger
model of Thomson
Plum pudding model
model of Rutherford
Nuclear model
model of Neils Bohr
Planetary model
model of Schrodinger
Quantum Mechanical model
are assigned the values in order of increasing energy; n=1,2,3,4
Principal Energy Levels
small massive structure located at the center of atom and carries a positive electrical charge
Nucleus
the volume occupied by the electrons
Electron cloud
equal to number of protons and electrons
Atomic number
the relative weight of the atom of an element
Atomic weight
the sum of the number of protons and electrons and is also equal to the atomic weight
Mass number
atoms of a given element having the same atomic number but different atomic weights
Isotopes
the orbits in which the electrons revolve designated by numbers 1, 2, 3, 4
Maini energy levels
s p d f
sharp
principal
diffuse
fundamental
region of space around a nucleus where an electron with a specific energy is most likely to be found
Orbital
number of orbital per sublevel
s - 1
p - 3
d - 5
f - 7
limits the number of electrons in any orbital to not more than two and this pair of electrons must be spinning in opposite direction
Pauli Exclusion Principle
for a given sublevel, each orbital must be occupied by a single electron before pairing of electrons in any orbital of that sublevel to occur
Hund’s rule
the distribution of electrons using this method indicates the energy level and sublevels that are filled
s p d f notation
using arrows to represent electrons and boxes for orbitals
Rectangular Arrow Method
nucleus is shown with its protons and neutron and the electrons are found outside the nucleus rotating in a definite path
Complete Atomic Structure
symbol is shown and the electrons are distributed represented by half shell
Half-shell notation
the nucleus is represented by the symbol of the element and only the electrons on the last shell are distributed along the atom using dots, dashes, etc.
Electron Dot Notation/Lewis Structure
