Transcript Subatomic Particles - Ciencias Esmeralda

HOMEWORK:
For next Monday Sept 9th
CONSTRUCT BY HAND
PERIODIC TABLE
ON CARTULINAOF 21.5 x 28 cms
And Write about ANY of the families of
the ELEMENTS
Only Symbols, Atomic number and
atomic weight
Bohr model
In atomic physics, the Bohr model, introduced by Niels Bohr in 1913,
depicts the atom as small, positively charged nucleus surrounded by
electrons that travel in circular orbits around the nucleus—similar in
structure to the solar system, but with attraction provided by electrostatic
forces rather than gravity. After the cubic model (1902), the plumpudding model (1904), the Saturnian model (1904), and the Rutherford
model (1911) came the Rutherford–Bohr model or just Bohr model for
short (1913). The improvement to the Rutherford model is mostly a
quantum physical interpretation of it. The Bohr model has been
superseded, but the quantum theory remains sound
Amu: Atomic mass unit
U:1 g /60..22x10(22) mol(-1)
Avogadro=Number of atoms or molecules in one mole
1. Subatomic Particles
Particle
Electrons
Symbol
(table O)
e
0e
-1
0β
-1
Protons
Neutrons
Charge
Mass
(amu)
Location
Within atom
structure
Negative
(-1)
1/Avogardos
0 amu
Outside
nucleus
( in various
energy levels)
p
1p
1
1H
1
Positive (+1) 1 amu
Nucleus
n
Neutral
(0)
Nucleus
1n
0
1 amu
Special notes on subatomic particles
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In a neutral atom # of protons=#of electrons.
Atoms are electrically neutral.
If the number of protons does not equal the number
of electrons you have a charged atom known as an
ion.
# protons > # electrons forms a + ion (cation)
# electrons > # protons forms a – ion (anion)
The charge on the nucleus is positive.
Most of the mass of an atom is in nucleus.
1. Atomic Number (z)
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1913—Henry Mosley (Untroduced the
concept)
Is used to identify an atom
Indicates the number of protons
In a neutral atoms also gives the number of
electrons
Also called the Nuclear Charge
3. Mass Number (A)
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Total number of protons and neutrons in
the nucleus of an atom. (nucleons)
Notation: AXZ
Mass # = #protons + # neutrons
# neutrons = Mass # - # protons
36=p+ and e
no=48
Exercise:
*Mass # = #protons + # neutrons * protons= Num. Electrons
*# neutrons = Mass # - # protons
Sample Atom
Notation
Protons
(atomic #)
Neutrons
(mass #atomic #)
Electrons(s
ame as
atomic#)
Carbon-12
C-12
12C
6
6
12-6=6
6
Chlorine-35
Cl-35
35Cl
17
17
35-17=18
17
Chlorine-37
Cl-37
37Cl
17
17
37-17=20
17
Neon-20 Ne20
20Ne
10
10
20-10=10
10
*ATOMIC MASS
Oxygen Atom Structure
Determine the # of protons, neutrons,
and electrons for these added
examples:
 19F9
 9 protons
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19-9=10 neutrons
9 electrons
 19F9-1 -1 Negatively charged
 9 protons
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10 neutrons
10 electrons
 24Mg12
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12 protons
24-12=12 neutrons
12 electrons
 24Mg12+2
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Positively Charged
12 protons
12 neutrons
10 electrons
1. Isotopes
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Thomson (1912) found 2 types of neon atoms and
Soddy (1910) found 2 types of uranium atoms.
2 elements that have the same atomic number but
different mass numbers
Based on atomic structure: 2 elements that have
the same number of protons but different number
of neutrons.
For example: Cl-35 and Cl-37
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Isotopes are not random. Isotopes are formed
based on their stability. The more chemically stable
an isotope is the higher abundance it will have.
Some isotopes are radioactive and are therefore
described as radioisotopes
For example 14Carbon is a radioactive isotope of
carbon whereas 13Carbon are stable isotopes
therefore is in abundance over 14Carbon.
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Carbon Atom
Used for radiocarbon dating
Carbon 14 Isotope
5. Atomic Mass (Different than Mass NUMBER?)
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Decimal number (Explain)
Average of all the naturally occurring
isotopes for a particular element
If you round the atomic mass it gives you the
mass number for the most common isotope.
Unit is amu (atomic mass unit)
1 amu is 1/12 the mass of C-12
Gram atomic mass= amu but in grams
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IF HYDROGEN ATOM STRUCTURE IS
Neutron?:
Try the following:
1.
Determine the number of protons, neutrons,
and electrons for the following isotopes of
hydrogen: H2;H3
Solution:
Hydrogen-2 (deuterium) 2H1
Hydrogen-3 (tritium) 3H1
1p,1n,1e
1p,2n,1e
1.
Naturally occurring chlorine consists of
75% Cl-35 and 25% Cl-37. Find the
average atomic mass.
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.75(35) + .25(37)= 35.50 amu or
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75(35) + 25(37) =35.50 amu
100
3. Calculate the atomic mass of an element with isotope A
occurring 70.0% of the time with a mass of 13.0 amu and
isotope B occurring 30.0% of the time with a mass of 15.0 amu.
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.70 (13.0) +.30 (15.0) =13.6 amu
1.
An element X has three isotopes
X-30 has a 50.0% abundance, X-28 has a 30.0%
abundance and X-31 has a 20.0% abundance.
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.500(30) + .300(28) + .200 (31) = 29.6 amu
5. There are two isotopes of element Z, 60.0% of the
atoms have a mass of 58.0 amu and 40.0% have a
mass of 57.0 amu. Calculate theatomic mass of
element Z.
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.600(58.0) + .400(57) = 57.6 amu