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Inside the Atom - lesson 1- 2

Terms in this set (25)

elements
An element is matter made of atoms of only one kind.
Ex: Iron is an element made up of iron atoms.
atom
basic unit of matter, You could take a piece of matter , cut it in half, cut the half piece in half again. and continue to cut again and again. Eventually you wouldn't be able to cut any more . You would have only one particle left. They named these particles as atoms.,a term that means "can not be divided".
Dalton
believed the atom was a hard sphere that was the same throughout
J.J. Thompson
used the cathode-ray tube experiment to show that atoms could be divided into smaller particles
electrons
particles in the atom that have a negative charge
Rutherford experiment
showed that alpha particles could pass through foil because most of the atom is empty space
protons
particles that have a positive charge
neutrons
particles in an atom's nucleus that do not have an electrical charge
Isotopes
Isotopes are atoms of the same element that have different numbers of neutrons. Ex: he isotopes of carbon called carbon-12, carbon-13 and carbon-14. All isotopes has 6 protons but different number of neutrons
atomic mass
the mass of the protons and neutrons
Atomic number
The atomic number of an element is the number of protons in the nucleus of an atom of an element.
electron cloud
region surrounding nucleus where electrons are most likely to be found
mass number of an isotope
the number of protons plus the number of neutrons
isotopes
atoms of the same element that have a different number of neutrons
number of neutrons
subtract the number of protons (atomic number) from the mass number
stable isostope
has the same number of protons as neutrons
strong nuclear force
holds the protons together
radioactive decay
the release of nuclear particles and energy
alpha particle
contains 2 protons and 2 neutrons
transmutation
the changing of one element into another through radioactive decay
beta particle
high energy electron released from the nucleus
tracer elements
have short half lives - used to diagnose disease
carbon-14 Carbon Dating
cannot be replaced when an organism dies,Carbon dating is only used for things that have been alive. It is useful in determining the age of artifacts and fossils.
americium-241
used in smoke detectors
Half-life
The half-life of a radioactive isotope is the amount of time it takes for half of a sample of the element to decay.
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