Chapter 4 Jaelyn Sutphin (parts of the atom, an atom is the smallest…
Chapter 4 Jaelyn Sutphin
Democritus-observed and believed that atoms were invisible of indestructible but his approach was not based on the scientific method.
John Dalton-Used Democritus ideas on atoms and formed them into the scientific theory by using experimental methods. Dalton's atomic theory: all elements are composed of tiny invisible particles called atoms, atoms of the same element are identical, atoms of different elements ca be physically mixed together or can chemically combine to form compounds, and lastly chemical reaction occur when atoms are separated joined or rearranged.
J.J. Thomson- Discovered the electron, cathode ray.
Robert Millikan-Carried out experiments to find the quantity of charge carried by an electron.
Ernest Rutherford- Gold foil experiments, tested alpha particles , the theory of atomic structure, passed through, he said "this is almost as incredible as if you fired a 15-inch shell at a price of tissue paper and it came back and hit you.
James Chadwick-Confirmed the existence of another subatomic particle, the neutron.
parts of the atom, an atom is the smallest particle of element.
Electrons- negatively charged subatomic particles.
Neutrons- big subatomic particles with no charge.
protons-big positively charged subatomic particles
Nucleus- the tiny central core of an atom and is composed of protons and neutrons.
Neutral atoms have the same number of protons and electrons
positive ions have more protons than electrons
negative ions have fewer protons than electrons
element symbol meaning
top number: the atomic number which is based on the number of protons in the nucleus.
chemical symbol: the letter in the middle, first letter capitalized if there is a second number it is always lowercase.
Average mass number: Average atomic mass, number at the bottom, always round
protons and nucleus are the same size as well as their masses.(equal) 1840 times bigger than an electron
Symbol readout box
a=element symbol, A one or two letter abbreviation to represent the full name of an element.
b=charge, the difference between electrons and protons
c=atomic number, identifies the number of protons.
d=mass number, identifies the number of protons and neutrons
A in the middle, d top left, b top right, c lower left
Method one: X middle/off center to right A top left, Z bottom left
A=mass number= # nucleons= #p +#n
X= element symbol
Z= Atomic number= number of protons
Example. Iodine= atomic number:53, Mass number:131, Number of protons:53, Number of electrons: 53, Number of Neutrons: 78, X-A notation: I-131, Method one notation, Capital I with 53 in the bottom left.