ATOMIC THEORY
The basic building blocks of matter that make-up everyday objects. Defining the Atom An atom is the smallest particle of an element that retains its identity in a reaction. The basic building blocks of matter that make-up everyday objects.
How small is an atom?
About a million atoms stacked on top of each other = the thickness of a sheet of paper. Copyright © 2010 Ryan P. Murphy
About 5 million atoms make up a period at the end of a sentence. Copyright © 2010 Ryan P. Murphy
Video Link! The size of atoms http://www.youtube.com/watch?v=yQP4UJhNn0I Copyright © 2010 Ryan P. Murphy
DemoCritus Early Greek Scholar-was the first to suggest the existence of atoms He believed that atoms were indivisible and indestructible. Never developed a theory lacked experimental support
John Dalton’s Atomic Theories -All matter is composed of tiny indestructible particles called atoms. -Atoms cannot be made or destroyed. -All atoms of the same element are identical. -Different elements have different types of atoms. -Chemical reactions occur when atoms are rearranged. -Atoms of different elements can mix together to form compounds.
Dalton’s Theory Revised Most of Dalton’s theory is still accepted today EXCEPT that atoms are known to be divisible. Atoms can be broken down into 3 subatomic particles: electrons, protons and neutrons.
J.J. Thomson Used a cathode ray tube to prove the smallest particles present must have a negative charge. http://www.youtube.com/watch?v=RW_zfKOU9uM&feature=related
+ - - Copyright © 2010 Ryan P. Murphy
+ - - + Copyright © 2010 Ryan P. Murphy
+ - Like charges (-) (-) repel. The Electron is negative. - + Copyright © 2010 Ryan P. Murphy
+ - - + Copyright © 2010 Ryan P. Murphy
+ - + - Copyright © 2010 Ryan P. Murphy
+ - + - Copyright © 2010 Ryan P. Murphy
+ - Opposite charges attract (+) (-). The electrons are negative. + - Copyright © 2010 Ryan P. Murphy
+ - What did this study find? + - J.J. Thompson discovered the ELECTRON!!! + - + - Copyright © 2010 Ryan P. Murphy
J.J. Thomson Atoms were electrically neutral, so there must be a + particle to cancel out the – charge from the electron. Developed the Plum Pudding Model (positive ball containing scattered electrons)
Ernest Rutherford Former student of Thomson, DISPROVED the Plum Pudding Model of the atom. The Gold Foil Experiment: Sent a beam of + charges (alpha particles) through a piece of very thin gold foil. Angles of deflection were measured.
Turn Sound On Copyright © 2010 Ryan P. Murphy
Copyright © 2010 Ryan P. Murphy
Copyright © 2010 Ryan P. Murphy
Copyright © 2010 Ryan P. Murphy
Copyright © 2010 Ryan P. Murphy
Copyright © 2010 Ryan P. Murphy
Copyright © 2010 Ryan P. Murphy
Rutherford Results: Most of the alpha particles passed straight through, most of the foil must be regions of “empty” space – not a + sphere like Thomson believed. + charges and the atoms mass must be found in the center discovered the nucleus
The Nuclear Atom In Rutherford’s atomic model, the protons and neutrons are located in the nucleus. The electrons are distributed around the nucleus and occupy almost all the volume of the atoms.
Video! Rutherford’s Gold Foil Experiment http://www.youtube.com/watch?v=5pZj0u_XMbc Copyright © 2010 Ryan P. Murphy
Neils Bohr Model (1913): Depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus . Copyright © 2010 Ryan P. Murphy
The atom consists of three fundamental particles - Copyright © 2010 Ryan P. Murphy
Proton + (positive charge) Copyright © 2010 Ryan P. Murphy
Proton + (positive charge) Copyright © 2010 Ryan P. Murphy
Proton + (positive charge) Copyright © 2010 Ryan P. Murphy
Proton + (positive charge) Copyright © 2010 Ryan P. Murphy
Proton + (positive charge) Copyright © 2010 Ryan P. Murphy
Neutron 0 (neutral charge / no charge) Copyright © 2010 Ryan P. Murphy
Neutron 0 (neutral charge / no charge) Copyright © 2010 Ryan P. Murphy
Neutron 0 (neutral charge / no charge). Copyright © 2010 Ryan P. Murphy
A neutron walks into a video store. Copyright © 2010 Ryan P. Murphy
He asks the clerk “How much are the movies?” Copyright © 2010 Ryan P. Murphy
“For you…” “No Charge.” He asks the clerk “How much are the movies?” Copyright © 2010 Ryan P. Murphy
“For you…” “No Charge.” He asks the clerk “How much are the movies?” Copyright © 2010 Ryan P. Murphy
He asks the clerk “How much are the movies?” Copyright © 2010 Ryan P. Murphy
Electron – (negative charge) Copyright © 2010 Ryan P. Murphy
ATOMIC STRUCTURE Particle Charge Mass proton + ve charge 1 neutron No charge 1 electron -ve charge nil
number of electrons = number of protons ATOMIC STRUCTURE He 2 Atomic number the number of protons in an atom 4 Atomic mass the number of protons and neutrons in an atom number of electrons = number of protons
Why are atoms electrically neutral? HELIUM ATOM shell proton N + - + N - neutron electron Why are atoms electrically neutral?
What atom is this? How can you tell? Copyright © 2010 Ryan P. Murphy
Answer! (2 Protons) Atomic #2 Copyright © 2010 Ryan P. Murphy
Answer! (2 Protons) Atomic #2 (Helium) Copyright © 2010 Ryan P. Murphy
Answer! (2 Protons) Atomic #2 (Helium) Copyright © 2010 Ryan P. Murphy
Review! To find # of protons and electrons Copyright © 2010 Ryan P. Murphy
Review! To find # of protons and electrons It is the atomic number, or count the P+ or E-. Copyright © 2010 Ryan P. Murphy
Review! To find # of protons and electrons It is the atomic number, or count the P+ or E-. Copyright © 2010 Ryan P. Murphy
Review! To find # of protons and electrons It is the atomic number. What is this atoms Atomic number? Copyright © 2010 Ryan P. Murphy
Answer! Copyright © 2010 Ryan P. Murphy
Answer! Count the 11 Protons or 11 Electrons Copyright © 2010 Ryan P. Murphy
Answer! Atomic Number 11. What element is #11 Copyright © 2010 Ryan P. Murphy
Answer! Atomic Number 11. What element is #11 Sodium Copyright © 2010 Ryan P. Murphy
Review! To find # of neutrons Copyright © 2010 Ryan P. Murphy
Review! To find # of neutrons Subtract the atomic number from the atomic mass to determine the difference. Copyright © 2010 Ryan P. Murphy
Review! To find # of neutrons Subtract the atomic number from the atomic mass to determine the difference. How many neutrons does Lithium have? Copyright © 2010 Ryan P. Murphy
Atomic Mass Review! To find # of neutrons Subtract the atomic number from the atomic mass to determine the difference. How many neutrons does Lithium have? Atomic Mass Copyright © 2010 Ryan P. Murphy
Atomic Mass Atomic Number Review! To find # of neutrons Subtract the atomic number from the atomic mass to determine the difference. How many neutrons does Lithium have? Atomic Mass Atomic Number Copyright © 2010 Ryan P. Murphy
6.94 amu – 3 = Atomic Mass Atomic Number Review! To find # of neutrons Subtract the atomic number from the atomic mass to determine the difference. How many neutrons does Lithium have? Atomic Mass Atomic Number 6.94 amu – 3 = Copyright © 2010 Ryan P. Murphy
6.94 amu – 3 = Atomic Mass Atomic Number Answer! 6.94 – 3 = 3.94 Copyright © 2010 Ryan P. Murphy
6.94 amu – 3 = Atomic Mass Atomic Number Answer! 6.94 – 3 = 3.94 or 4 neutrons Atomic Mass Atomic Number 6.94 amu – 3 = Copyright © 2010 Ryan P. Murphy
Complete the following table in your notes Atomic # Mass # # of Protons # of Neutrons # of Electrons 9 10 14 15 47 22 55 25