Honors Chemistry Chapter 4 and 16

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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- +


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