Chapter 2 Flashcards
(26 cards)
3 Types of Matter Discussed in this Chapter :
Atoms, Molecules, Ions
Who said that all matter consists of small indivisible particles called atoms?
Democritus 5th Century BC
Who formed the atomic theory?
John Dalton 1808
What is the atomic theory?
1) all matter is composed of small indivisible (atoms)
2) atoms of a given element identical in mass and chemical behavior (diff=diff)
3) 2 or more atoms join in simple, fixed ratios to form compounds (Law of Multiple Proportions
4) in a chemical reaction, atoms are rearranged to form different compounds; atoms are not created nor destroyed (Law of Conservation of Mass)
What is the Greek word for uncuttable/indivisible?
Atomos
What states that two are more atoms joining simple fixed ratios to form compounds?
Law of multiple proportions
What states that atoms are not created or destroyed?
Law of conservation of mass (matter)
Who used a tube filled with gas to show that gas molecules were excited and a beam of light went from left to right.
When magnets were placed above the tube, a positive pull of the magnet went up & the negative pull down below
JJ Thompson JET
Who used a tube filled with gas whose excited molecules shot in a beam from left to right and came up with the charge/mass ratio?
JJ Thompson 1897
Jet - tube filled with gas, excited molecule beam from left to right, upwards towards positive magnetic plate on top
Said there has to be something negative in the gas that caused it to attract up to the positive magnetic plate.
Based on the deflections he can’t up with the charge to mass ratio of -1.76*10^8 coulombs/grams
Who came up with the plum pudding model?
JJ Thompson
What is this ? Who came up with it?
Plum Pudding Model by JJ Thompson
A magnet embedded inside a sphere of positive charge filled with negative electrons. This allowed the atom to be neutral
Who use charged oil droplets, and found that the charges were all multiples of one small number? What was that number?
How do you get the mass of an electron from this number and what is the mass of an electron?
Robert Millikan 1909
-1.6*10^-19 coulombs = charge of an electron
We multiply Milligan’s charge of an electron by 1/Thompson’s charge to mass ratio = mass of e- = 9.1*10^-28g
Who discovered rays that could not be deflected by a magnet? And what were they called?
Wilhelm Rontgen X-Rays
Who claimed that raise from uranium were energetic and not deflected by magnets?
Antoine Becquerel 1896
Who was Antoine Becquerel’s student who coined the term “radioactive”?
Marie Curie
Who used thin gold foil as targets for Alpha particles from a radioactive source?
1910 Ernest P Rutherford
What was the observation made from the experiment using gold foil as targets for alpha particles from a radioactive source?
Ernest Rutherford Observations:
Most particles penetrated foil undeflected, a few were highly deflected
Most of the particles traveled through the foil undeflected, which he determined meant that the atom was mostly empty space. Some alpha particles are deflected by small angles determining the nucleus is positively charged so there had to be something positive in the gold foil that was causing these deflections.. once in a while, the deflections would actually travel backwards, telling us that the nucleus carries most of the atoms mass
What was Ernest Rutherford‘s conclusions in the gold foil experiment?
ERP - protons
1) Most of the atom is empty space
2) the nucleus is small compared to the size of the entire atom
3) the nucleus is the center, and
4) the nucleus carries most of the atoms mass
5) POSITIVE PARTICLES WERE CALLED PROTONS
Who bombarded beryllium with alpha particles, and found high energy, neutral particles were emitted?
What did he call these particles?
James Chadwick - Neutrons
Who studied the electron and what was its charge?
EMT
Electron- negative
Millikan
Thompson
9.1*10^-28g
Who studied the proton and what was its charge?
PR Proton+ Rutherford
Rutherford 1.67*10^-24g
Who studied the neutron and what was its charge?
NC No charge
Neutron Chadwick
1.67*10^-24g
What gives the number of protons in the nucleus?
Atomic Number
