Question | Answer |
What did J.J Thompson calculate? | Charge to mass ratio- (e/m = 1.758820x10^8 C/g) |
What did Millikan calculate? | The charge of an electron. |
What did J.J Thompson's cathode ray experiment prove? | atoms give off negatively charged electrons. Also, those atoms must contain positively charged particles to balance the charge. |
What is significant about J.J Thompson's Plum Pudding Model? | He proposed that electrons "corpuscles" were surrounded by a positively charged soup, like a blueberry muffin. |
What is significant about Rutherford? | He created a Gold foil experiment that debunked Thompson's plum pudding model. |
What is significant about Rutherford's gold foil experiment? | It used alpha particles- a type of emission given off by some naturally occurring radioactive elements.
When he aimed a stream of alpha particles at the foil, he noticed almost all went through the foil without being deflected. |
What did Rutherford take away from his Gold Foil Experiment? | A metal atom is mostly empty space and the mass is concentrated in a tiny central core that he calls the nucleus. |
What two particles is the nucleus composed of? | protons and neutrons |
What makes one atom different than another? | The atomic number |
What do protons and electrons have in common? | they equal each other |
Neutrons? | neutrons are uncharged, but they add up to an atom's mass number |
Mass Number | protons plus neutrons |
Isotopes | Isotopes of an atom have the same atomic number but different mass numbers
Isotopes of the same element have the same number
of protons but different number of neutrons |
Atomic Mass | a weighted average of isotopic
masses of an elements naturally occurring isotopes. |
Using AMU as a conversion factor | If a diamond has a mass of 1.00 grams, how many atoms does the diamond contain?
1.00g (1amu/1.6605x10-24grams)(1carbonatom/12.011amu) = 5.02x10^22 c atoms |
what is Avogadro's number? | it is a quantity, just like a dozen that we use to count atoms and molecules. one mole of carbon atoms equals 6.022x10^22 c atoms |
Using Avogadro's number as conversion factor | how many moles of carbon atoms are in the diamond? 5.02x10^22 C atoms (1mole/6.022x10^23 atoms) =0.0834 mol C |
Molar Mass | mass in grams of one mole of any element. units are g/mol |
What does Avogadro's number tell us? | How many atoms are in a mole. |
What do we use Avogadro's number to convert between? | atoms and moles 1mole= 6.022x10^22 |
What is Nuclear Chemistry? | the study of properties and changes of atomic nuclei |
Nuclear Reaction | involves a change in the atom's nucleus, usually producing a different element. |
Radioactive Isotopes | undergo spontaneous decomposition (decay)and emit some form of radiation. |
Radiation | The emission of energy as electromagnetic waves or moving subatomic particles. there are three types found by Rutherford, alpha, beta, and gamma! |
Alpha Radiation | is attracted/deflected to a negative electrode |
Beta radiation | is attracted/deflected to a positive electrode |
Gamma | unaffected by magnetic and electric fields |
What are the two other radioactive decay processes in addition to alpha and beta? | Positron Emission and Electron Capture. |
Positron Emission | occurs when a proton in a nucleus changes to a neutron and ejects a positron. |
What is a positron | thought of as a positive electron, same mass of electron but opposite charge. |
what is electron capture? | happens when a proton in the nucleus an electron and turns into a neutron.
The atomic number will decrease (one fewer proton) and mass number is unchanged. |
How can we think of electromagnetic energy? | As Waves |
What is electromagnetic energy characterized by? | frequency, wavelength, and amplitude. |
Wavelength x Frequency equals? | Speed |
What is Frequency? | the number of wave peaks to pass a given point per unit of time. |