radioactivity and stuff

The discovery of radioactivity

French physicist Henri Becquerel was interested in the ability of certain substances to transform the UV light falling on them into visible light

Becquerel kept a set of minerals in a desk drawer along with a set of un-exposed photographic plates

One day, he takes these plates out to use. When he develops the plates, they are terribly blurred, as if previously exposed to light

Becquerel deduced that the presence of a piece of uranium ore in the same drawer as the photographic plates was sufficient to blur the them

Penetrating radiation

gamma ray and x-ray radiation have the ability to penetrate considerable thickness of a material. An individual photon may travel several cm or farther into tissue before it interacts.

Radiation

something being emitted during the decay of an unstable nucleus

What is radioactive decay?

Radioactive decay is the process by which unstable atomic nuclei break down into smaller fragments.

What causes natural radioactive decay?

Natural radioactive decay is attributed to the intrinsic instability of nuclei of certain elements.

What particles are ejected during radioactive decay?

Radioactive decay causes the ejection of energetic alpha and beta particles.

What type of radiation is emitted during radioactive decay?

High-energy electromagnetic radiation, known as gamma rays, is emitted during radioactive decay.

alpha radiation

A stream of high energy α particles

helium nucleus consisting of 2 protons & 2 neutrons

Most damaging in its path- Least penetrating can be stopped by a sheet of paper

beta radiation

A stream of β particles-

A β particle is an electron

Intermediate in its effects- Can be stopped by clothing or a thin sheet of aluminum foil

gamma radiation

high energy electromagnetic radiation

it is not a stream of particles

most penetrating - can be stopped by several inches of lead or several feet of concrete

What is the effect of ionizing radiation on cells?

Cells can be damaged, leading to radiation burns.

How does ionizing radiation affect DNA?

It can damage DNA, which may lead to mutations such as cancer.

What factors influence the damage caused by ionizing radiation?

The damage depends on the type of radiation absorbed.

what may happen when ionizing radiation comes in contact with a cell

pass through without damage

damage the cell but the cell fixes itself

damage the dna causing a mutation

kill the cell

natural nuclear reaction

sun

background radiation

human caused

artifical sources

cosmic radiation

radon gas

Radioactive material that comes up from the ground and can penatrate basements, causing indoor pollution

rads

absorbed radiation is measured in rads

rads = roentgen absorbed dose

carbon 14 decay

Method to date fossils based on radioactive decay.

formation of carbon 14

produced in upper layers of the atmosphere

carbon dating

a scientific method used to determine the age of an artifact

radiometric dating

length of half lives determines their utility

useful for dating materials very very olddd

tritium dating

Tritium is a radioactive isotope of hydrogen. It has a half-life of 12.26 years and can be used for dating objects up to 100 years old.

u-238 dating

abundant isotope of uranium

can be used to measure age of rock

half life

length of time required for half of the radioactive atoms in a sample to decay

linear growth/decay

quantity increases decrease by the same absolute amount in each unit of time

exponential growth/decay

quantity increases/decreases by the same relative amount in each unit of time

exponential decay equation

q = q0(0.5)^t/T

doubling is same js with a 2

formula for time in decay

T*log(q/q0)/log(0.5) = t

doubling is same js with a 2

formula for half life in decay

T = t*log(0.5)/log(q/q0)

doubing is same js with a 2