Science Weekly Schedule

Monday	Tuesday
Bohr video Chadwick Reading W.S. 4.3 (due T)	Pg. 18-20 on Protons, neutrons, electrons and isotopes

Science Weekly Schedule

Monday	Tuesday	Wednesday	Thursday	Friday
-Rutherford Essay Test -Hunting the Elements	- Hunting the Elements	- Hunting the Elements	- Hunting the Elements	-Bohr video and Chadwick reading

Hunting the Elements

Here is a link to the movie we're watching in class

Rutherford Writing

Rutherford

Rutherford was working with radioactive uranium.  He applied a very strong magnet to the rays given off by the uranium and discovered it was actually 3 rays: gamma, beta and alpha.  The alpha rays were made of massive, + charged particles.  He decided to use these as “bullets” to explore the inner structure of the atom.

 He fired them at a thin gold foil.  Because they had so much mass, he expected they would go straight through.  Most did go straight through, but some were deflected and scattered in odd directions.  Some even bounced straight back!

The alpha particles must have hit something.  For an alpha particle to bounce back, the mass of an atom must be concentrated in a tiny area carrying a + charge.  Rutherford had discovered the nucleus.  The - charged electrons must be moving to avoid getting pulled into the + charged nucleus.  This is just like our planets moving around the sun to avoid getting sucked in by its gravity. For this reason, Rutherford’s model is called the planetary model.

Rutherford later found there were positively charged particles within the nucleus so he also discovered protons.

Thomson Writing

Thomson

In Thomson’s experiment he used a Crookes Tube, which is kind of like an old-school TV tube, to discover something new about atoms.  He found that he could bend the ray in a Crookes Tube using a magnet.  The ray bent towards the + side and away from the – side.  Because opposite charges attract and like charges repel, Thomson said the beam must have a – charge.

Because Thomson knew the strength of the magnetic field, the deflection of the beam and the speed of the particles in the beam, he could use an algebra equation to find the mass of the particles.  The mass turned out to be about 2000 times smaller than the lightest atom, hydrogen.  Thomson had discovered something smaller than an atom, the electron!

Thomson’s evidence led him to see atoms not as solid, featureless spheres, but as a spongy, positively-charged material with negatively charged electrons stuck in it, like blueberries in a blueberry muffin.

Weekly Schedule

Monday	Tuesday	Wednesday	Thursday	Friday
-Dalton Essay Test -Correct pg. 8, 12 -Thomson reading + notes	-Thomson Writing -Rutherford marble lab HW Thomson Writing	-Rutherford marble lab -Rutherford Reading HW Thomson Writing	-Thomson Essay Test -Rutherford Reading	-Rutherford Practice Writing(test M) HW Rutherford Writing

Dalton Writing

Dalton, an English schoolteacher and amateur meteorologist, noticed how water could magically disappear into the air (evaporation) and later reappear as clouds and rain.  He reasoned that this could only happen if air was made up of tiny individual particles (atoms) with lots of empty space between them.  Dalton thought that not just air, but all matter, was made of atoms.

To him atoms were solid, indestructible spheres with no internal structure and atoms of different substances had different masses.  These atoms combined in simple, whole number ratios to make everything around us.

Of all the substances he looked at, hydrogen was the lightest so he gave hydrogen atoms a mass of 1, the smallest integer.  He found weights of other substances in relation to hydrogen, e.g. oxygen was 8X heavier than hydrogen so it was given a mass of 8.

Pre-Atomic Essay

Since ancient times, there have been many ideas of what everything around us was made of.  One of the oldest ideas is that of four basic “elements”.  A Greek philosopher named Empedocles said that these four elements were earth, air, fire and water.  These four elements came about from combination of four qualities, cold, hot, wet and dry.  For example, earth was cold + dry and fire was hot + dry.  The four elements combined in different proportions to make the wide variety of substances in the world.  For example, Empedocles thought bone was made up of ½ fire, ¼ water and ¼ earth.

Since everything was made up of different proportions of these four basic elements, the alchemists thought that they should be able to change things into gold by changing the ratio of these 4 elements in a substance to that of gold.  They weren't successful, but learned a lot about substances in the process.

Democritus was the first person to come up with the idea of atoms.  He saw them as the smallest particles.  They could not be cut in two.  According to him they were hard and solid and came in many different sizes and weights.  A substance’s atoms gave the substance its properties.  For example, water had smooth atoms because you can pour water and it’s smooth and soft to the touch.

Unfortunately, the idea of atoms didn't take hold because one of the most influential thinkers of all time, Aristotle, believed in the 4 elements theory.

Weekly Schedule

Monday	Tuesday	Wednesday	Thursday	Friday
-Phlogiston Match Quick Lab-Priestly Reading + notes-Lavosiere Reading + notes	-Questionnaire-Pre-Atomic essay writing practice-HW copy essay	-Dalton Reading + notes-Candle Experiment-Electrolysis video-HW copy essay	-Dalton writing-Thomson Q’s pg. 8 due F-HW copy essay	-Pre-Atomic essay Exam-HW Dalton Writing