#### Transcript Atomic Structure - What you should already know

```Atomic Structure
The atom as we understand it
today
Atomic Structure
The atom consists of 3 subatomic particles?
Do you know what they are?
Proton
Electron
Neutron
Atomic Structure
The following notation is used:
A
X
Z
A = Mass Number
Z = Atomic Number
Atomic Structure
Atomic Number (Z) – this is unique to each atom.
The atomic number is equal to the number of
protons.
Mass Number (A) – this is the total mass of each
atom. Remember, each P and N has a mass of
amu = 1/12 the mass of a C-12 atom
Therefore, the mass number = #P + #N
Atomic Structure
The atom written as 3617Cl can also be
expressed as Cl-36.
The 17 is understood, because we are
referring to the chlorine atom.
The 36 refers to the Mass Number.
Atomic Structure
Element
C-12
F-14
N-14
Na-25
Li-8
Atomic #
Make the following grid
Mass #
#P
#N
#e
Atomic Structure
Element
Protons
119
Make the following grid
238
50Sn
92U
17
85
Neutrons
92
Electrons
82
Atomic Number
Mass Number
36
92
92
235
Atomic Structure
Can we have both U-235 and U-238?
Yes! They are referred to as Isotopes.
Isotopes are atoms of the same element
(they have the same number of P) but they contain
a different number of Neutrons. (This is what
changes the mass number)
Atomic Structure
Now what do we do when we are given:
60 Co2+
27
We now have:
P: 27
N:33
e-: 25 (We have two fewer electrons than P)
Atomic Structure
***WARNING***
Never change the number of protons when a
charge is present, ALWAYS change the
number of e-.
A positive charge (More P than e-)
A negative charge (More e- than P)
Atomic Structure
Element
Protons
25
Make the following grid
2+
126
12Mg
85
18
26
28
Atomic Number
Mass Number
3+
17
Neutrons
Electrons
51Sb
36
10
51
13
27
```