Early Atomic Theories
Theorized that all matter is made up of small invisible particles called Atoms
Democritus
What is the A number, and what does it tell us?
The mass number, tells us the number of protons and neutrons in the nucleus.
127.91 amu (18.75%)
128.95 amu (29.40%)
129.98 amu (51.85%)
What is the average atomic mass of element R?
129.29 amu
if Rb-89 undergoes beta decay, what will it become?
isotope: xenon-137
fraction remaining: one half (1/2)
wanted: number of half-lives?
1 half life
Solid Sphere Model
John Dalton
What is the term for elements that may have different numbers of neutrons in the nucleus?
isotopes
24.99 amu (42.27%)
25.90 amu (11.63%)
26.94 amu (46.10%)
What is the average atomic mass of element X?
25.99 amu
What type of decay is the least penetrating?
Alpha
Iron-59 has a half-life of 44.6 days. If you start with a 64-gram sample, how much Iron-59 is left after 133.8 days?
8 grams remain
Discovered the electron using a cathode ray, came up with the plum pudding model
J.J. Thomson
Metals __gain/loose_ electrons. This is called a _cation/anion__, which means they have a __positive/negative__ charge.
loose/cation/positive
127.99 amu (29.02%)
128.90 amu (16.33%)
129.94 amu (51.19%)
130.98 amu (3.46%)
What is the average atomic mass of element J?
129.24 amu
Xenon-147 decays to produce caesium-147 and a high energy electron. What type of nuclear reaction or decay is this?
Beta decay
isotope: copper-64
percentage remaining: 3.13%
wanted: number of half-lives?
5 half-lives
This person conducted the Gold Foil Experiment, and determined that the atom is mostly empty space. He also discovered the nucleus and what other subatomic particle?
Ernest Rutherford; proton
What subatomic particles are in Hg2+ if its mass number is 184?
80 protons
104 neutrons
78 electrons
52.94 amu (94.64%)
53.95 amu (1.55%)
54.98 amu (2.55%)
55.96 amu (0.21%)
56.90 amu (?%)
What is the average atomic mass of element P?
53.06 amu
Radium-213 decays to produce radon-209 and a helium nucleus. What type of nuclear reaction or decay is this?
Alpha Decay
isotope: curium-245
total time: 59500 years
percentage remaining: 0.78%
wanted: length of half-life?
8500 years
Who discovered the Nuetron?
James Chadwick
Given the element neon with the atomic number 10,
and the mass number 22;
1• determine the # of protons, neutrons, & electrons.
2• write it in isotopic notation
1. 10 p+, 12 n0, 10 e-
2. 22/10 Ne
231.92 amu (17.19%)
232.92 amu (51.09%)
233.92 amu (?%)
234.94 amu (16.53%)
What is the average atomic mass of element H?
233.23 amu
If Thallium-215 undergoes beta decay, what will it become?
Lead-215
A radioactive sample of Iodine-131 has a half-life of 8 days. If a 200-gram sample decays until only 12.5 grams are left, how much time has passed?
32 days