midterm review. chem.

Who was the first person to propose the idea that matter was not infinitely divisible.
Democritus
Democritus believed matter was made up of tiny individual particles called, _, from which the English word atom is derived.
atomos
Democritus believed that atoms could be created, destroyed, or further divided. true or false.
false. he believed that they couldn’t be.
Democritus received much criticism for his ideas from other scientists, one of them being _. Why were these criticisms received?
Aristotle; They would ask what holds the atoms together, and he could not answer the question.
Aristotle rejected Democritus’ theory entirely. true or false.
true
Aristotles ideas were..
he denied the existence of atoms.
John Dalton came up with..
Dalton’s Atomic Theory
All matter is composed of extremely small particles called atoms, atoms cannot be created divided or destroyed, and that in a chemical reaction atoms are separated, combined, or rearranged are all parts of..
Dalton’s Atomic Theory
Was all of Dalton’s theory accurate?
no
Wad Dalton’s atomic theory a huge step toward our current atomic model of matter?
yes
What was Dalton wrong about?
He was wrong about atoms being indivisible, (they are now divisible into several subatomic particles) and about all atoms of a given element having identical properties (atoms of an element mayy have slightly different masses)
Do all atoms of a given element have identical properties?
no
Are atoms indivisible?
no
_ is the smallest particle of an element that retains the properties of the element.
an atom
What does the scanning tunneling microscope allow you to do?
see individual atoms
Why was the accidental discovery of the cathode ray so significant?
it led to the development of the television
Negatively charged particles that are part of all forms of matter are now known as _
electrons
Who began a series of cathode ray tube experiments to determine the ratio of its charge to its mass?
J.J. Thomson
Thomson concluded that the mass of the charged particle was much less than that of a _ atom, the lightest known atom.
hydrogen
Who was the person that identified the first electron/ discovered it?
J.J Thomson
How did Thomson prove that Dalton was wrong?
He proved that atoms were divisible into smaller subatomic particles.
Who determined the charge of an electron?
Robert Millikan
A single electron carries a charge of _
-1
J.J Thomson proposed a model of the atom that became known as the …
plum pudding model
Did the plum pudding model of the atom last long?
no
Who conducted the gold foil experiment?
Ernest Rutherford
Rutherford concluded by his experiment that the _ was incorrect because it could not explain the results of the gold foil experiment.
plum pudding model
Rutherford calculated that an atom is..
consisted mostly of empty space through which the electrons move
Rutherford also concluded that there was a tiny, dense region, called the _, centrally located within the atom that contained all of an atom’s positive charge and virtually all its masss.
nucleus
Rutherford concluded that the nucleus contained positively charged particles called
protons
A _ is a subatomic particle carrying a charge equal to but opposite that of an electron; that is, a _ has a positive charge of _
proton, proton, +1
James Chadwick showed that the nucleus also contained another subatomic particle, a neutral particle called the _
neutron
Who discovered the neutron?
James Chadwick
A _ has a mass nearly equal to that of a proton, but it carries no electrical charge.
neutron
Three subatomic particles that are the fundamental building blocks from which all atoms are made from are _, _, and _.
electron, proton, neutron
Where is the electron located?
in the space surrounding the nucleus
Where are the protons and neutrons located?
in the nucleus
Electron are held within the atom by their attraction to the _ _ _.
positively charged nucleus
Who discovered that atoms of each element contain a unique positive charge in their nuclei.
Henry Moseley
The number of protons in an atom is referred to as the element’s ….
atomic number.
True or false; The period table is organized left to right and top to bottom by decreasing atomic number.
false; it’s organized by increasing atomic number.
true or false ;
Atomic # = # of protons = # of electrons
TRUE (p. 98 )
Atoms with the same number of protons but different numbers of neutrons are called _
isotopes
true or false. Isotopes do not differ in mass.
false; they do differ
The number added after the element’s name to help make it easy to identify each isotope of an element is the _
mass number
True or false; Number of neutrons = mass number – atomic number.
true.
amu stands for..
atomic mass number
What is the weighted averaged mass of the isotopes of an element..?
atomic mass
What do you need to calculate the atomic mass of an element?
number of naturally occurring isotopes, their masses, and their percent abundances
A nuclear reaction involves a change in an atom’s _
nucleus
_ is a process in which some substances spontaneously emit radiation.
radioactivity.
The rays and particles emitted by the radioactive material is called _
radiation
Unstable nuclei lose energy by emitting radiation in a spontaneous process ( a process that does not require energy) called .. ?
radioactive decay
Scientists named the radiation that was deflected toward the negatively charged plate .. ?
alpha radiation
Alpha radiation is made up of.. ?
alpha particles
Each alpha particle contains _ protons and _ neutrons, and thus has a _ charge.
2, 2, +2
Since opposite electrical charges, attract, it explains why the _ particles are attracted to the negatively charged plate.
alpha
An alpha particle is equivalent to a helium-4 nucleus, which is represented by
4He
2

and it’s also represented by the fish thing that represents jesus!

The radiation that was deflected toward the positively charged plate is called
beta radiation
beta radiation consists of fast moving electrons called
beta particles
Beta particles are represented by
0B( fancy looking B)
-1
What is the charge for Beta?
-1
Whats the charge for Gamma?
What are high-energy radiation that posses no mass and are denoted by the symbol 0/0y
gamma rays
Because they possess no electrical charge, _ are not deflected by electric or magnetic fields.
gamma rays
x

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