Chemical Ideas 2.1. A simple model of the atom.. What’s inside? In the nucleus? Protons And around...
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Transcript of Chemical Ideas 2.1. A simple model of the atom.. What’s inside? In the nucleus? Protons And around...
Chemical Ideas 2.1.
A simple model of the atom.
What’s inside?In the
nucleus?
ProtonsAnd around the nucleus?
ElectronsNeutrons
How are they
different?Mass
Charge
Location
Mass on Ar scale
Charge
p 1 +1
n 1 0
e- 0.00055 -1
Nuclear symbols
Na23
11
Mass number =?
Atomic number =?
p + n
p ( = e-)p?
e-?
n?
•11
•11
•12
What are isotopes?
Cl35
17Cl
37
17
p?
e-?
n?
p?
e-?
n?
17
17
18 20
17
17
•Atoms of the same element with:
•The same atomic number but different mass numbers
•Same number of protons but different numbers of neutrons
Why is 35Cl O.K.?
Cl35
17Cl
37
17
Relative isotopic mass
Cl-35 Cl-37
Chlorine always has an atomic number of 17!
So what is relative atomic mass?
Cl-35
Cl-37
75%
25%
Relative atomic mass is the average of the relative isotopic
masses
Cl-35
Cl-37
75%
25%
How do we get a relative atomic mass of 35.5?
What 2 things did we need to know?
Relative isotopic masses.
The relative abundances.
How do we find them out?
Use a mass spectromete
r
Mass spectrometry
Ionisation andfragmentation
Sample in here
Magnetic fieldElectric field
Mg
e-
e-
Mg+
Ionisation andfragmentation
Sample in here
Magnetic fieldElectric field
Cl-35
Cl-37
A mass spectrum …
35 3736
20
40
60
80
100
%
mass
A mass spectrum …
24 2625
20
40
60
80
100
%
mass
Try W and Y!