Term
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Definition
| extremely small particle of matter that retains its identity during a chemical reaction |
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Term
Dalton's atomic theory (1803)
part 1
true/false |
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Definition
"all matter is composed of indivisible atoms"
false, atoms can be subdivided into electron, protons, neutrons |
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Term
Dalton's atomic theory (1803)
part 2
true/false |
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Definition
"an element is a type of matter composed of only one kind of atom, each atom of which has the same properties"
false: isotopes of an element have different properties |
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Term
Dalton's atomic theory (1803)
part 3
true/false |
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Definition
"a compound is a type of matter composed of atoms of two or more elements and chemically combined in fixed proportions"
true |
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Term
Dalton's atomic theory (1803)
part 4
true/false |
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Definition
atoms are not created, destroyed, or broken into smaller particles by any chemical rxn
true |
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Term
Applications of Dalton's atomic theory:
Law of conservation of mass |
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Definition
| total mass doesn't change during a chemical rxn |
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Term
Deductions from Dalton's atomic theory:
Law of multiple proportions |
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Definition
when 2 elements can form more than one compound, the masses of one element in these compounds (for a fixed mass of the other element) are in small whole number ratios
ex: carbon monoxide has 1.3321g O for 1g C
carbon dioxide has 2.6642g O for 1g C |
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Term
discovery of the electron (1897)
by whom? how?
significance? |
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Definition
JJ Thompson with the cathode ray tube;
-cathode rays composed of negatively charged particles (deflected toward positive plate)
-cathode rays are independent of the gas and material of electrodes
-determined mass-to-charge ration, Me/e=5.6x10^-12 kg/C; called particle electron |
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Term
Oil drop experiment (1909)
who? significance? |
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Definition
-Robert Millikan
-determined value of charge of electron: e=1.602x10^-19 C
-w/ Thomson's data, mass of electron is determined to be approximately 1/1800 other mass of the lightest atom (H, a proton) mH = 1.674x10^-27 kg |
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Term
nuclear model of the atom:
rocks and photographic plates (1896);
who? significance? |
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Definition
Henri Bequerel
rocks overexposed his photographic plates, therefore the rocks were producing light, therefore were radioactive |
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Term
nuclear model of the atom:
Marie Curie said? |
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Definition
| "radioactivity" shows that atoms are made of smaller particles |
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Term
nuclear model of the atom:
splitting radiation (1903)
who?
significance? |
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Definition
Rutherford; showed alpha particles were He2+ ions and B-rays were electrons
-alpha radiation showed nucleus changing, therefore atoms are not unchangeable atoms |
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Term
nuclear model of the atom:
Gold foil experiment (1909)
who? sig? |
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Definition
| hans geiger and ernest marsden; found approx. 1 in 8,000 a-particles scattered. this was used for the basis of Rutherford's nuclear model |
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Term
| Rutherford's nuclear model (1911) |
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Definition
-nucleus is positively charged
-nucleus is small compared to the atomic diameter (10^-10 m versus 10^-15m) |
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Term
Rutherford (1911):
when a-particles collide w nitrogen and other gases, ______ form? |
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Definition
| hydrogen nuclei (protons) |
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Term
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Definition
| when a-particles struck beryllium target, strongly penetrating radiation was produced |
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Term
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Definition
| showed that some radiation consistes of a neutral particle with a mass approx. that of a proton (neutrons) |
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Term
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Definition
core of atom
comprises most of the mass of atom, along w one or more units of positive charge |
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Term
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Definition
neg charge particle
very light
exists in region around positive nucleus |
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Term
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Definition
positively charged particle
equal in magnitude but opposite charge of electron
mass is 1836 times that of electron, nearly the same as neutron's |
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Term
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Definition
no charge
mass nearly identical to proton's |
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Term
atomic number:
symbol, definition |
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Definition
Z
number of protons in nucleus
(determines chemical identity of the atom) |
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Term
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Definition
A
number of protons + neutrons
(protons and neutrons give particle its mass) |
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Term
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Definition
| atoms of a element with same number of protons but differing number of neutrons |
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Term
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Definition
distinguishes isotopes of an element
A/Z X
X= element symbol |
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Term
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Definition
can separate different isotopes of an element;
one can obtain percent abundance of isotopes by calculating the relative peak areas |
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Term
| C-12 = X atomic mass units? |
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Definition
| c-12 has a mass of exactly 12 amu |
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Term
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Definition
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Term
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Definition
| the weighted average of the isotopic weights of an element, based on the isotope's relative natural abundance |
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Term
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Definition
number of C-12 atoms in exactly 12g of C-12;
6.022x10^23 |
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Term
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Definition
mass of one mol of a substance;
is mass is in grams, MM is numerically equal to atomic weight in amu's. |
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Term
types of decay:
alpha emission (a)
symbol?
changes in A or Z? |
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Definition
4/2 He,
2 protons, 2 neutrons
daughter has 2 less protons (Z parent-2), and 2 less neutrons (A parent -4) |
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Term
beta emission (B)
equivalent to?
change in A or Z? |
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Definition
0/-1 e,
one electron,
equivalent to the conversion of a neutron to a proton
(therefore, atomic number goes up one (Z parent +1); mass number does not change, A parent= A daughter) |
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Term
positron emission (B+)
equivalent to?
change in A or Z? |
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Definition
0/1 e
a positively charged electron,
equivalent to the conversion of a proton to a neutron;
daughter has one less proton (therefore Z parent-1 = Z daughter), and A doesn't change (A parent = A daughter) |
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Term
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Definition
1/1 P + 0/-1 e --> 1/0 n
occurs when a nucleus captures an inner orbital e-
equivalent to proton and electron combining to make a neutron;
A parent = A daughter; Z daughter = Z parent-1;
will see emission of X ray photon |
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Term
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Definition
0/0 Y (a photon)
radioactive decay may result in a daughter nucleus in an excited state (metastable nucleus); nucleus relaxes to a lower energy state by emission of a Y-photon; |
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Term
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Definition
| nucleus with an excited state lifetime less than or equal to 10^-9s |
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Term
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Definition
cannot use physical means to separate a substance into other kinds of matter;
possess definite intensive physical and chemical properties |
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Term
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Definition
| cannot be decomposed by any chemical means into simpler substances |
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Term
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Definition
composed of more than one element, chemically combined;
law of definite proportions: a pure compound, no matter its source always contains definite, constant proportions of the elements by mass
ex: NaCl from china is the same as NaCl from clinton |
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Term
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Definition
| can be separated with psychical means into two or more substances |
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Term
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Definition
a mixture consisting of physically distinct parts (phases)
ex: oil and vinegar |
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Term
| homogenous mixture (SOLUTION) |
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Definition
a mixture that is uniform throughout
ex: salt water |
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Term
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Definition
notation for chemical compounds based on atomic symbols with subscripts indicating the relative proportions of the atoms in the substance;
recall law of definite proportions;
ex: Fe2O3 = 2Fe: 3O; H2O = 2H: 1O; NaCl= 1Na:1Cl |
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Term
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Definition
a definite group of atoms that are chemically bonded together;
covalent bond (2/more atoms sharing electrons, usually a pair);
can be notated by molecular formulas, structural formulas, molecular models |
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Term
| some elements are molecular substances; list them. |
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Definition
H. Bronclif;
H2, Br2, O2, N2, Cl2, I2, F2 |
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Term
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Definition
composed of ions held together in a regular arrangement in space by the attraction of their opposing charges (Ionic bond)
ex: NaCl crystal |
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Term
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Definition
| electrically charged particle obtained by adding or removing electrons from an atom or chemically bonded group of atoms |
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Term
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Definition
| positively charged ion formed by the loss of electrons from neutral atoms |
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Term
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Definition
| negatively charged ion formed by the gain of electron by a neutral atom |
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Term
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Definition
expressed in terms of smallest unit (formula unit);
given that all substances are electrically neutral, we can deduce the formula for an ionic compound;
ex: Cl- ions + Ba2+ ions formula unit = BaCl2 |
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