1 Negative particles Positive particles Neutral particles.
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Transcript of 1 Negative particles Positive particles Neutral particles.
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Negative particles
Positive particles
Neutral particles
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Why do most of the alpha particles pass through?
31 angstrom = 1 x 10-10 m
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nucleus
Protoncharge = +, mass = 1.0073 amuatomic mass units: 1amu = 1.6605402 x 10-24 g
Neutroncharge = neutral, mass = 1.0087
Electroncharge = 1-, mass = 5.4586 x 10-4 amu
Almost all the mass is in the nucleus,and
almost all the volume is due to the electrons!
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Almost all the mass is in the nucleus,and
almost all the volume is due to the electrons!
One penny If this penny consisted of just nuclearmaterial it would weigh……...
190,000,000 TONS!!!
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In a neutral atom, the number of (+) protons = the number of (-) electrons
And.. The number of protons is equal to the atomic number of the element.
Since the mass of an atom is almost entirely located in the nucleus, the mass number is equal to:the number of protons PLUS the number of neutrons
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The lower numbers found on most periodictables are the ATOMIC MASSES (WEIGHTS)NOT the ATOMIC MASS NUMBER!
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Isotopes: same element, different atomic mass.
How can this be?
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Isotopes: same element, different atomic mass.
How can this be?
If it’s the same element ,the number of protons
can’t change. So what must change?
Isotopes: same element, different number of neutrons.
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11C 12C 13C 14C
ISOTOPES
No. protons:
No. Electrons:
No. neutrons:
6 6 6 6
6 6 6 6
5 6 7 8
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N147
N157
99.63%14.0031 amu
0.37%15.0001 amu
ISOTOPES OF NITROGEN
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C126
C136
C-12 basis for the atomic mass scale
C146
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Atomic mass or weight: the weighted average of the atomic masses of all naturally occurring isotopes present.
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35.45Cl
Atomic #
Atomic mass or weight
Cl3517 75.53%
Cl3717
24.47%
Naturally occurring ISOTOPES:
34.9689 amu
36.9659 amu
x 0.7553 = 26.412
x 0.2447 = 9.045
35.45Atomic mass onperiodic table
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“Losers”Metals lose e-’s in chemical reactions
Boy there area lot oflosers!
15non-metals: gain electrons (or share)
metalloids:
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Why is O a non metal and Po a metal?
Nucleus
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1
234
56
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periods
periods
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1
234
56
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Groups or families
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Molecular Compounds: (molecules)
CO2
CO
H2O2
O3
H2O
O2
CH4
C2H4
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7 diatomic elements
6 + 1 = 7
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Molecular structures:
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Molecular and Empirical Formulas:
Simplest Form
Actual formula
butene: C4H8 molecular or empirical?
What is the empirical formula? CH2
Carbon dioxide: CO2 empirical or molecular?
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Ions and ionic compounds:
cation: positive charge (lost e-’s)
Na+ 11 protons and only 10 electrons
anion: negative charge (extra e-’s)
Cl -17 protons and 18 electrons
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