Make this table in your iSNAtoms cannot be divided

Electron Nucleus Electrons orbit nucleus

Electrons in Energy levels

Electron Cloud

Greek Dalton Thomson Rutherford X X XBohr X X X XShrodinger and Heisinberg

x x x x x

How did we figure out these very, very, small particles existed?

As we go, 1) check the boxes that apply in your table2) draw a diagram for each model.

Atom Videos: Nanotechnology

How small are atoms?

http://www.firecold.com/videos/the-real-size-of-an-atom

KEY POINTS Atoms are so small it is difficult to imagine.

Atoms are mostly empty space. Drawings of the atom don’t show his because otherwise the nucleus would not be visible.

The nucleus is very dense!

Which is smaller, a cell or an atom? Also…they both have a nucleus?

http://learn.genetics.utah.edu/content/begin/cells/scale/

Nucleus = the center

Nucleus of a cell contains DNA which contains atoms.

Everything else in the cell is made of atoms.

The nucleus of an atom contains protons and neutrons

An atom is 1,000,000 times smaller than a cell!

Greek Model

Democritis- Greek philosopher

400 BC Idea of ‘atomos’ – at some

point, matter cannot be further divided

Based on philosophy, not science

This theory was ignored and forgotten for more than 2000 years!

Dalton’s Theory- 1803

• All elements are made of atoms. Atoms can’t be divided or destroyed.

• Atoms of the same element are exactly alike.

• Atoms of different elements are different.

• Compounds are formed by the joining of atoms of two or more elements.

Thomson Model- 1897

• Plum Pudding model.

• Atoms were made from a positively charged substance with negatively charged electrons scattered about, like raisins in a pudding.

Rutherford

• ****positively charged particles were contained

in the nucleus.

• negatively charged particles were scattered outside the nucleus around the atom’s edge.

http://www.youtube.com/watch?v=bSEOOMs5VNU

http://www.youtube.com/watch?v=hJs6PcgqMPA&feature=related

Gold Foil Experiment

Bohr Model- 1913• The electrons

move in energy levels

• located at specific distances from the nucleus.

1925- Electron Cloud Model

it is impossible to determine the exact location of an electron, but we can estimate probabilities.

More complex than energy levels. According to the modern atomic model, at atom has

a small positively charged nucleus surrounded by a large cloud-like region of electrons

What does your table look like?Atoms are cannot be divided

Electron Nucleus Electrons orbit nucleus

Electrons in Energy levels

Electron Cloud

Greek XDalton XThomson XRutherford X X XBohr X X X XShrodinger and Heisinberg

x x x x x

We have seen several atomic ‘models.’

What is the scientific definition of a model? When would you use a model?

Can we think of other examples of models?

The Electron Cloud model is the newest model.

1) Does that make it the ‘best.’

2) Why is it useful to look at the other models?

Want to learn more?Search terms for your investigation:

Democritus – Billiard ball model John Dalton JJ. Thomson – plum pudding modelErnest Rutherford- Gold Foil Experiment

Inside of protons and neutrons- Quarks, Gluons

Details on experiments- Glencoe book pg 62-74

How is an atom held together?

http://learningcenter.nsta.org/lcms/default.aspx?a=so&gid=1162&tid=372&soid=72

Then…how is the Nucleus Held Together?

Then…how is the Nucleus Held Together?

In sum, the force holding the nucleus together is stronger than the repulsive force of the positively charged protons.