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Who thought matter was sformed of air, eath, fire, and water? Greek philosophers
it was commonly accepted that ______ could be endlessly divided into smaller and smaller pieces matter
___________was the first person to propose matter was _________________ Democritus; not infinitely divisible
Democritus believed that matter was made up of tiny particles called? atomos
________ revised and revived Democtitus's ideas. JOhn Dalton
Daltons ________ included: all matter is composed of extremely small particles called ________ Atomic theory; atoms
All atoms have the same size, mass, and chemical properties. True
Atoms of a specific element are the same from those of any other element False; different
Atoms cannot be_________ or ________ created or destroyed
In a ___________________ atoms are seperated,________ or reorganized Chemical reaction; combined
The smallest particle of an element that retains the properties of the element is called an atom
______ are so small that they can only be seen by using a ____________________ atoms; scanning tunneling microscope
negatively charge particles that are part of all forms of matter are called? electrons
the electron was discovered by _____________ j.j thomson
_________ proposed the ____________ atomic model thomson; plum pudding
___________ determined the mass of an electron to be 9.1 X 10 (-28) g Robert Millikan
Ernest ________ performed ________ experiment. he discovered that atoms had a small dense center region called a _________ Rutherford; gold foil; nucleus
Rutherford also concluded that the nucleus of an atom conains ________ charged particles called protons positive
subatomic particle that carries a charge equal to but opposite than that of an electro proton
________ showed that the nucleus also contained a neutral particle called the ________ James chadwick; neutron
A neutron has a mass nearly equal to that of a ____________ but carries no ___________ charge Proton; electrical
number of protons in an atom is atomic number
___________ determines an elements position on the ____________ atomic number; periodic table
Atomic Number= number of protons= number of electrons true
atoms with the same number of protons but different number of ____________ are called _________ neutrons; isotopes
represents the sum of the number of protons and neutrons in the nucleus mass number
= atomic number from the mass number number of neutrons
mass of subatomic particles is measured int atomic mass units
atomic mass unit is defined as 1/2 the mass of a carbon-12 atom
weighted average mass of the isotopes of that element atomic mass
_____________ involve an atom of one element changing into an atom of another element nuclear reactions
substances that emit radiation radiactive
the ____ and ________ emitted by a radioactive material is called radiation rays and particles
radioactive atoms emit radiation because their _______ are unstable Nuclei
made up of alpha particles alpha radiation
consists of fast moving electrons called beta particles beta radiation
consists of gamma rays ( high energy radiation that possess no mass) gamma radiation
a ________equation show the atomic number and mass number of the particles involved nuclear
Created by: Tonya#33



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