Download Atomic Structure Notes

Unit 2: Atoms and Elements
AP Chemistry
Atomic Structure Notes
Parts of Atoms:
Most people already know that the atom is made up of
three main parts, the ___protons__________ and
__neutrons__________ in the nucleus and the
______electrons______ somewhere outside of
the nucleus.
Any atom that has 23 protons is __Vanadium_______.
Any atom that has 92 protons is ___Uranium_______.
Let’s summarize:
symbol
charge
location
proton
p+
+1
Nucleus
neutron
n0
0
Nucleus
mass
size (see below)
1836
10-15 m
1839
10-15 m
electron
e-1
Outside
nucleus
1
-18
10 m
Let’s make this more visual using information from
the Chart of Fundamental Particles.
If the proton were 10 cm in diameter… or the size of
an orange, how big would everything be?
object
proton
neutron
electron
atom
How Many Particles in Each Atom?
The particle that defines the identity of an atom is the
___proton______. (shown on the periodic table)
Every hydrogen atom has _1_ proton.
Every magnesium atom has _12_ protons.
actual size
10-15 m
10-15 m
10-18 m
10-10 m
model size
10 cm
10 cm
7 cm
18 cm
model
orange
orange
plum
melon
The atom is often represented as a miniature
__electron______ ____cloud______. Draw it:
The mass of the atom is due to the
_____protons and neutrons_____
The size of the atom is due to the
___electrons____________
The mass of an atom is mostly from the __protons___
and ____neutrons________.
Find O on the periodic table. It’s mass is _16.00___
amu.
It has _8_ protons. It must have _8_ neutrons.
Electrically neutral atoms (as opposed to ions) have
one electron for every proton.
Fill in this chart for these neutral atoms:
Atom
Mass
protons
neutrons
electrons
He
4.003
2
2
2
Si
28.09
14
14
14
Be
9.012
4
5
4
H
1.008
1
0
1
Rn
(222)
86
136
86
Ar
39.95
18
21
18
F
19.00
9
10
9
Pb
207.2
82
125
82
If the mass is not close to a whole number, it is
because the atom has several ___isotopes______.
These are atoms with the same number of
__protons_________ but different numbers of
___neutrons__________.
Chlorine has two isotopes: Cl-35 ( _17_ p+ & _18 n)
and Cl-37 ( _17_ p+ & _20_ n).