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from- http://learning.mgccc.cc.ms.us/pk/sciencedocs/subatomicparticles.htm
Proton (p+) is positively
charged particle of the atomic nucleus. The atomic number
of an element represents the number of protons in the
nucleus.
Electron (e-) is negatively
charged particle that can occupy a volume of space (orbital)
around an atomic nucleus. All atoms of an element
have the same number of electrons (i.e. any Chlorine atom is
going to have 17 electrons). Electrons can be shared or
transferred among atoms.
Atoms have an equal number of
protons and electrons; therefore, they have a no net charge.
Ion is an atom that has gained
or lost one or more electrons, thus becoming positively or
negatively charged.
Neutron is an uncharged
particle of the nucleus of all atoms EXCEPT hydrogen. For a
given element, the mass number is the number of
protons and neutrons (nucleons) in the nucleus.
Isotope is one of two or more
forms of atoms of an element that differ in their number of
neutrons. They have the same atomic number (same number of
protons and electrons), but a different mass number due to more
or fewer neutrons.
| Particle |
Charge |
Relative Charge** |
Mass |
Relative mass** |
Location |
| Proton |
+1.60 x 10-19 C |
+1 |
1.672 x 10-24 g |
1 amu |
nucleus |
| Electron |
-1.60 x 10-19 C |
-1 |
9.05 x 10-28 g |
0 amu ~(1/1840
amu) |
electron cloud
(orbital) |
| Neutron |
neutral |
0 |
1.674 x 10-24 g |
1 amu |
nucleus |
**Using relative charges and masses are used
to keep calculations simple.
Atomic Number
The atomic number is the number of protons in
the nucleus of an atom. It is listed on the periodic table for
each element. No two elements have the same atomic number (or
the same number of protons), so the atomic number identifies
the element.
: (symbol: Z)
Mass Number
Mass number: (symbol: A) total number of
protons and neutrons in the nucleus (not listed on the
periodic table, since it varies). NOTE
this number is a whole number. Atomic
Mass is different.
Atoms of the same element have the same atomic number,
but may have different mass numbers.
Isotopic notation for a particular atom (also called
nuclide symbol notation):
(E
= element's symbol; A = mass number; Z = atomic number)
For example:
Represents a sodium atom which always has 11
protons and in this case has a mass number of 23.
(Note: This means that there are 12 neutrons. 23 - 11 = 12)
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Mass number - atomic
number = # neutrons
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Determining the
number of electrons-
The number of electrons in an element can
change. For a neutral atom, the number of protons is exactly equal
to the number of electrons. So the number of electrons is the same
as the atomic number. However, it is possible to remove electrons
and not change the identity of an element. These are called ions.
The charge on the ion tells you the number of electrons.
If the charge is positive,
subtract that number from the atomic number to get the number of
electrons. You have more protons.
If the charge is negative,
add the amount of charge to the atomic number to get the number of
electrons.You have more electrons.
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Determine
the number of protons, neutrons, and electrons present
in each of the following atoms.
(mass
# = top number, atomic # = bottom number)
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|
|
a)
28 |
Si |
a
protons = 14, electrons = 14,
neutrons = 14 |
| 14 |
|
b) 197 |
Au |
b
p = 79, e = 79, n = 118 |
|
79 |
|
c)
40 |
Ar |
c
p = 18, e = 18, n = 22 |
|
18 |
|
d)
64 |
Cu |
d
p = 29, e = 29, n = 35 |
|
29 |
|
e)
39 |
K |
e
p = 19, e = 19, n = 20 |
|
19 |
|
f)
133 |
Cs |
f
p
= 55, e = 55, n = 78
|
| 55 |
| Identify
atoms that are isotopes in each of the following sets of
four atoms.
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|
|
A)
80 |
X |
82 |
X |
81 |
X |
A
80
|
X |
82 |
X |
|
35 |
35 |
36 |
35 |
35 |
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B)
19 |
X |
19 |
X |
17 |
X |
20 |
X |
B
19
|
X |
17 |
X |
| 9 |
10 |
9 |
8 |
9 |
9 |
|
C)
23 |
X |
24 |
X |
25 |
X |
C all |
|
11 |
11 |
11 |
|
D)
70 |
X |
70 |
X |
70 |
X |
70 |
X |
D none |
| 33 |
34 |
31 |
32 |
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W
tThe symbol, atomic number and atomic mass for the atoms
with the following characteristics. |
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|
| 1.
Contains
15 neutrons and 13 protons. |
1.
28 |
Al |
| 13 |
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b) 2.
Atomic
number is 41.
Neutrons 52.
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2. 93
|
Nb |
|
41 |
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c) 3.
Contains
33 electrons and 42 neutrons.
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3.
75
|
As |
| 33 |
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d) 4.
Iron
contains 84 subatomic particles.
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4. 58 |
Fe |
|
26 |
| 5. Rubidium that contains 87 nucleons. |
5.
87
|
Rb |
| 37 |
| 6. An ion with 17 protons, 18 neutrons and
18 electrons? |
6. 35 |
Cl |
1- |
| 17 |
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| 7. An ion with atomic number 16, mass number
of 32 and 18 electrons? |
7. 32 |
S |
2- |
| 16 |
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| 8. An atom with number of neutrons 15
and mass number 33? |
8. 33 |
Ar |
|
| 18 |
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| 9. Copper that lost 2 electrons and has 30
neutrons. |
9. 59 |
Cu |
2+ |
| 29 |
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| 10. Hydrogen that has 2 neutrons and
no electrons. |
10. 3 |
H |
+ |
| 1 |
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Complete the
Table Highlight to Reveal Answers
|
isotopes |
# protrons |
# neutrons |
# electrons |
| 85 |
Rb+ |
37 |
48 |
36 |
| 37 |
| 119 |
Sn4+ |
50 |
69 |
46 |
| 50 |
| 13 |
C4- |
6 |
7 |
10 |
| 6 |
| 235 |
U |
92 |
143 |
92 |
| 92 |
| 24 |
Na+ |
11 |
13 |
10 |
| 11 |
| 223 |
Fr+ |
87 |
136 |
86 |
| 87 |
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