Atomic Structure

Atomic Structure

What are Atoms? Atoms are tiny units that determine the properties of all matter. Atoms are the building blocks of molecules

Atomic  Models There have been five major atomic models, including the one in use today. 1. Around 400 BC a Greek scientist  called Democritus said that matter was made up of small particles he named 'Atoma' (meaning indivisible).

2. John Dalton Dalton - 1803 - round ball with a positive nucleus Element made up of atoms that cannot be divided Atoms of the same element are alike Atoms of different elements can join to form molecules

3. J. J. Thompson Thompson - discovered electrons in 1897

4. Lord Rutherford Based on his alpha-particle scattering experiment on gold, Rutherford concluded that the atom consisted of a hard central core where most of the mass of the atom rested. Rutherford - discovered the nucleus 1911 http://www.learnerstv.com/animation/animation.php?ani=121&cat=chemistry

5. Neils Bohr http://dwb4.unl.edu/ChemAn ime/BOHRQD/BOHRQD.ht ml Bohr - electrons  travelin paths  (energy levels)  around the nucleus  - 1913 http://web.visionlearning.com/ custom/chemistry/animations/ CHE1.3-an-atoms.shtml

Summary of Atomic Models Dalton's Model Atoms are billiard-like spheres Thomson's Model Electrons are imbedded in a positive sphere Rutherford's Model Positive dense tiny nucleus is surrounded by electrons in empty space Bohr's Model Electrons orbit the nucleus Electron Cloud Model Electrons do not travel in orbit but fill space like a cloud with no definite position, but definite energy levels

Modern Theory - electrons do not  move in definite paths but the exact  position, speeds and direction of  electrons cannot be determined. Modern -  electron cloud  theory replaced  Bohr’s model in  1925 http://intro.chem.okstate.edu/1314F97/Chap ter6/BohrQuantum.html

Protons A PROTON is a positively charged subatomic particle in the nucleus of an atom Positive Mass = 1 amu = 1.67 x 10-24 g Discovered by E. Goldstein in 1886 Symbol – p+

Neutrons A NEUTRON is a neutral subatomic particle in the nucleus of an atom Neutral Mass = 1 amu = 1.67 x 10-24g Discovered by James Chadwick in 1932 Symbol - no

Chadwick - discovered the neutrons in 1932

Electrons An ELECTRON is a tiny negatively charged subatomic particle moving around outside the nucleus of an atom Negative charged Mass = 1/1840 amu = 9.11 x10-28 Discovered by J.J. Thompson in 1897   Symbol – e-1

The Atomic Nucleus Small Dense Positive charge Core of an atom Contains protons and neutrons Discovered by Ernest Rutherford  in 1911 P+ No

Label the diagram of the atom Label the diagram of the atom Electrons Electrons Nucleus Nucleus Neutrons Neutrons Protons Protons {

Valence electron - an electron in the  outermost energy level of an atom

Energy Level: any of the possible energies an electron may have in an atom Obital - a region in an atom where there is a high probability of finding electrons

p orbitals can hold a maximum of two  electrons so all three together can hod a  total of 6 electrons http://micro.mag net.fsu.edu/electr omag/java/atomic orbitals/index.ht ml As s orbital is shaped lie a sphere, so it  has only one possible orientation in space.  An s orbital can hold a maximum of two  valence electrons 3.1.5

e- enter lowest energy level first

The Atom 2 protons = +2 2 neutrons = 0 2 electrons = -2 Net charge = 0

http://www.quia.com/rr/263345.html

OBSERTAINER EXCERCISE

Bohr Models Obsenerators

Build Atoms  Yourself http://www.classzone.com/books/earth_science/terc/content/investigations/es0501/es0501page 04.cfm

http://highered.mcgraw- hill.com/sites/007299181x/student_view0/chapter16/bohr_atom_interactive.html#http://highered.mcgraw- hill.com/sites/007299181x/student_view0/chapter16/bohr_atom_interactive.html#

Atomic  Structure  Jeopardy Hangman http://www.quia.com/hm/110454.html http://www.quia.com/cb/147081.html

Rags to  Riches Matching  Vocabulary http://www.quia.com/rr/70834.html http://www.quia.com/cm/138746.html?AP_rand=374660492 http://www.quia.com/cm/138746.html?AP_rand=1276018100

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Atomic Structure