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Chapter 2
Atoms and Elements (Test 1)
Question | Answer |
---|---|
scientific model | an oversimplified conceptual picture to explain some aspect of nature |
John Dalton | developed the atomic theory; "billiard ball" model |
J.J. Thomson | cathode ray tube experiment; determined the charge to mass ratio of electrons; "plum pudding" model |
Robert Millikan | oil drop experiment; determined the charge of an electron (and thus the mass of an electron) |
Ernest Rutherford | gold foil experiment; showed that most of the mass of an atom lies in the nucleus (which is extremely tiny); destroyed the "plum pudding" model by establishing the "nuclear" model |
James Chadwick | discovered the neutron |
What are some characteristics of protons? | mass of about 1 amu; middle in mass between the other two subatomic particles; charge of +1 |
What are some characteristics of neutrons? | mass of about 1 amu; largest of the subatomic particles; charge of 0 |
What are some characteristics of electrons? | mass of about one two-thousandth amu; smallest of the subatomic particles; charge of -1 |
atom | a neutral particle |
ion | a charged particle |
cation | a positively charged particle |
anion | a negatively charged particle |
atomic number | the number of protons; this defines the element |
mass number | the number of protons plus the number of neutrons |
isotopes | atoms of the same element that differ from each other only by the number of neutrons. That is, they have the same atomic number but different mass numbers. |
atomic weight | a weighted average of isotopic masses |
The mass of one carbon-12 atom is exactly how many atomic mass units? | 12 amu |
Elements in a given what have similar chemical and physical properties? | vertical column or group |
group | vertical columns; sometimes called "families" |
period | horizontal rows |
metals | found on the left side of the periodic table; good conductors of heat and electricity; ductile, malleable, lustrous, tend to lose electrons and become cations |
metalloids or semi-metals | found on the stair step of the periodic table; properties of both metals and nonmetals |
nonmetals | found on the right side of the periodic table; insulators, brittle, dull, tend to gain electrons and become anions |
Group 1 | alkali metals |
Group 2 | alkaline earth metals |
Group 16 | chalcogens, "the oxygen family" |
Group 17 | halogens; very reactive |
Group 18 | noble gases; mostly nonreactive |
main group elements | groups: 1, 2, 13, 14, 15, 16, 17, 18 |
transition metals | groups: 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 |
inner transition metals | lanthanides and actinides |