Honors Chemistry Chapter 4 and 16
66 min (to two sig figs)
A radioactive isotope decayed to 17/32 of its original mass after 60 minutes. Find the half-life of this radioisotope.
came up with the atomic theory
Dalton
1803 AD
Dalton creates atomic theory
460 BC
Democritus develops the idea of atoms
3.34 seconds
Fermium-253 has a half-life of 0.334 seconds. A radioactive sample is considered to be completely decayed after 10 half-lives. How much time will elapse for this sample to be considered gone?
53.4 days
How long will it take for a 40.0 gram sample of I-131 (half-life = 8.040 days) to decay to 1/100 its original mass?
1872
Mendeleev creates periodic table
1.5:1
N:P ratio of larger atoms
1:1
N:P ratio of smaller atoms
8.75 g have decayed
Os-182 has a half-life of 21.5 hours. How many grams of a 10.0 gram sample would have decayed after exactly three half-lives?
1.28 x 1022 atoms remain
Pd-100 has a half-life of 3.6 days. If one had 6.02 x 1023 atoms at the start, how many atoms would be present after 20.0 days?
1912
Rutherford does gold foil experiment
12.5 g remaining
The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?
1897
Thomson discovers electrons
paper, clothes
alpha blocked by
beta particle
an electron emitted from the nucleus
isotope
atom of the same element with different number of neutrons
fusion
atoms come together to make something bigger
wood, metal, heavy clothes
beta is blocked by
radioactive element
element that emits particles
lead, concrete
gamma is blocked by
gamma ray
high energy electro-magnetic waves emitted from a nucleus
period
horizontal row of elements
fission
isotope breaks apart
Law of charges
like charges repel, unlike charges attract
1
mass of alpha
1/2000
mass of beta
0
mass of gamma
atomic number
number of protons
low
power of alpha
medium
power of beta
high
power of gamma
atom
smallest particle of an element
cathode ray
stream of small, negative particles
mass number
sum of the number of protons and neutrons
radiation
the emission of particles and/or energy from the nucleus
radioactive decay
the process of the spontaneous breakdown of radioisotopes
half-life
the time required for half of the atoms to decay
radioisotope
unstable isotope
group
vertical columns with similar properties aka families
gamma
waves of energy
atomic mass
weighted average of the naturally occurring isotopes
said everything must contain particles called atomos
what did Democritus do
created the periodic table of elements
what did Mendeleev do
gold foil experiment which showed the nucleus is the most dense and most of the volume of an atom is empty space
what did Rutherford do
discovered electrons via cathode ray
what did Thomson do
one more proton
what do you need to make a new element
strong nuclear force and neutrons
what holds the nucleus together
a nuclear reaction occurs in the nucleus and requires more energy
what is the difference between a nuclear reaction and a chemical reaction
strong nuclear force
what is the greatest force on earth
neutrons
what stabilizes the nucleus
all elements that are greater than 92
which elements are man-made
beta
0 -1. e
atomic mass unit
1/12 the mass of a carbon 12 atom (about the mass of a proton or neutron)
155.6 hours
100.0 grams of an isotope with a half-life of 36.0 hours is present at time zero. How much time will have elapsed when 5.00 grams remains?
117 58. Ce
121. 4 60 Nd ------> 2 He +
133 66 Dy
137. 4 68 Er ------>2 He +
154 73 Ta
154 0 72 -------->.-1 e- +
proton, neutron, electron
3 subatomic particles
alpha
4 2 He
46 24 Cr
46 0 23 V ------> -1 e- +
45 22. Ti
49. 4 24. Cr ------> 2 He +
68 34 Se
72. 4 36 Kr ------> 2 He+
77 39 Y
77 0 38 Sr ---------> -1 e- +