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Chapter 4: The Atom
Terms in this set (53)
the smallest unit of an element that contains all of the properties of that element (2 regions)
Atoms have what type of charge
How can atoms been seen
the ability to create atom-sized electronic devices (circuits;chips); future communications and medical applications
(early 1800s) used experimentation to relate Democritus's ideas unto scientific theory
Dalton's Atomic Theory
(e-) (1897) the negativity charged particle in the atom; extremely tiny, not considered in the mass of the elements; determines the chemical stability of the atom; large charge, tiny mass (attracted to + plate)
Who founded the electron?
determined the charge on an electron and used Thomson's experiment to determine the mass of an electron
Robert Millikan's Oil Drop Experiment
dense central region in an atom contains the protons and the neutron; positively charged; contains the majority of the mass in the element
Which scientists worked with the nucleus?
Rutherford, Marsden, Geiger
positively charged particle located in the nucleus; determines the chemical identity of the element
What has the perfect arrangement of electrons?
Who founded the proton?
Which was found first and why?
Electron because it has the most charge
neutrally charged particle located in the nucleus; composed of a proton and an electron fused together; slightly larger than a proton; determines the stability of the nucleus
Who founded the neutron?
James Chadwick (1932)
contains the electrons which orbit around the nucleus at relatively high speeds; contains the majority volume of the atom, neg. charged
Rutherford (1911) the atom is mostly empty space (FOUNDED THE AVERAGE ATOMIC MASS)
Gold Foil Experiment
(Z) the number of protons in the nucleus; each element has a different atomic number. (Henry Mosely)
Since atoms are neutral, they have the same number of what?
electrons and protons
total number of protons and neutrons in the atom; round off the average atomic mass to the nearest whole number
average of all the masses of all the isotopes of an element
Average Atomic Mass
Groups three through twelve do what
Elements to the left side of the green line do what
Elements to the right side of the green line do what
all matter is composed of atoms; atoms of any one element differ in properties from atom of another element (Uranium to Lead achieving stability)
Modern Atomic Theory
short-range forces the hold nuclear particles together despite same charges (why nucleus is so small)
The spontaneous emission of radiation (can be by an unstable atomic nucleus)
the rays and/or particles emitted by the radioactive material
a reaction that involves change in the nucleus of the atom that alters the chemical identity of the substance
occurs when unstable nuclei lose energy and change their identity by emitting radiation (particles and energy) until they achieve stability
occurs when a nucleus emits a particle that contains 2 protons and 2 neutrons; slow moving and large, very little penetrating power; should not be ingested
What happens to the atomic number in alpha decay/beta decay?
alpha- drops by two
beta- increases by one
What happens to the mass number in alpha/beta decay?
alpha- drops by four
two protons and two neutrons with a 2+ charge; a helium nucleus
Chemical reactions involve what two things?
the electron cloud and the nucleus
atoms of the same element that has a different number of neutrons; same number of protons. chemically alike
amu. mass of the atom; based on (-12, based on number of protons and neutrons and their relative abundance)
high energy radiation that possesses no mass, no charge; usually (not always) accompanies alpha and beta decay; tremendous penetrating power; deadly
a neutron is split apart into a proton and electron. the proton is kept in the nucleus and the electron is ejected from the nucleus; has a lot more penetrating power due to the speed of the particle, very small
(1895) discovered x-rays
(1896) first person to discover evidence of radiation using the mineral pictchblend
(1898) discovered the elements that produce the radiation in pictchblend
Marie and Pierre Curie
a nuclear reaction in which an element's atomic number is altered; one element changes into another
Nuclear stability is related to the
the time required for one half-life of radioactive sample to decay into its products
the splitting of the nucleus of an atom into fragments; releases tremendous amounts of energy; occurs at nuclear power plants; produces radioactive waste (absorbs neutrons, boiling water, any temp.)
occurs when two low mass nuclei are fused together; releases lots of energy; occurs on the sun; requires extremely high temps; (5,000,000 K); usually results in stable atoms (not controllable)
Methods of electricity
COAL, wind, water, solar panels
Problems with methods
coal- digging and mining; dangerous
wind- people at beach
water- restraining water; flood areas
solar panels- cloudy
How to detect radioactivity?
What experiment did JJ Thomson conduct
Cathode Ray Tube Experiment-charge to mass ratio
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