Atomic Structure Notes History of the Atom 1808

  • Slides: 12
Download presentation
Atomic Structure Notes

Atomic Structure Notes

History of the Atom • 1808 John Dalton – Matter made of tiny particles

History of the Atom • 1808 John Dalton – Matter made of tiny particles called atoms • 1897 Joseph Thomson – Discovery of electrons using cathode rays • 1909 Robert Millikan – Discovery of negative charge on electrons • 1911 Ernest Rutherford – Discovery of nucleus, lots of open space in an atom • 1914 Neils Bohr – Electrons orbit the nucleus in different shells • Modern Atomic Theory

 • Atom – The smallest particle of an element that retains the chemical

• Atom – The smallest particle of an element that retains the chemical properties of that element. • Nucleus – Positively charged center of the atom that consisting of protons and neutrons that contain nearly all the atoms mass with a very low volume.

 • Proton – Subatomic particle of the nucleus that has a positive charge.

• Proton – Subatomic particle of the nucleus that has a positive charge. • Neutron – Subatomic particle of the nucleus that has a neutral charge. • Electron – Subatomic particle outside the nucleus that has a negative charge.

Proton Neutron Nucleus Electron - Electron Region + N N +

Proton Neutron Nucleus Electron - Electron Region + N N +

Subatomic Particles Name Charge Weight Proton + 1 amu Neutron N 1 amu Electron

Subatomic Particles Name Charge Weight Proton + 1 amu Neutron N 1 amu Electron - . 0005 amu

 • Atomic Mass Unit – 1 amu, exactly 1/12 the mass of a

• Atomic Mass Unit – 1 amu, exactly 1/12 the mass of a carbon -12 atom. • Average Atomic Mass – The weighted average of the atomic masses of the naturally occurring isotopes of an element. • Isotopes – Atoms of the same element that have different masses.

 • Atomic Number – The number of protons in the nucleus of each

• Atomic Number – The number of protons in the nucleus of each atom of that element. Used to identify elements. • Mass Number – The total number of protons and neutrons in the nucleus of an atom. Mass # = Protons + Neutrons = Mass # - Protons

Mass Number, Protons, Neutrons and Electrons Element Protons Neutrons Electrons Mass # Hydrogen 1

Mass Number, Protons, Neutrons and Electrons Element Protons Neutrons Electrons Mass # Hydrogen 1 0 1 1 Carbon-12 6 6 6 12 Carbon-14 6 8 6 14 Oxygen-16 8 8 8 16 Oxygen-17 8 9 8 17

Hyphenated Notation Carbon – 14 Element Mass #

Hyphenated Notation Carbon – 14 Element Mass #

Atomic Number and Mass Notation 14 6 Mass # C Atomic # Symbol

Atomic Number and Mass Notation 14 6 Mass # C Atomic # Symbol

Relation of atomic mass and molar mass Carbon-12 • Atomic mass = 12. 011

Relation of atomic mass and molar mass Carbon-12 • Atomic mass = 12. 011 amu • Molar mass = 12. 011 g/mol • The only difference is the units