Atomic Structure-Nucleus
1
Anatomy of the Periodic Table
2
Building Blocks of Matter
•
– smallest unit of matter,
composed of p+, e-, no.
• ELEMENT – pure substance composed of a
single type of atom.
•
– multiple atom compounds
with covalent bonds, usually made up of only
non-metals.
• IONIC COMPOUNDS – multiple atom
compounds (not molecules), containing ionic
bonds, usually made up of a metal and a
non-metal.
3
Subatomic
particles
Name
Symbol
Relative
Charge mass
Actual
mass (g)
Electron
e-
-1
1/1840
9.11 x 10-28
Proton
p+
+1
1
1.67 x 10-24
Neutron
no
0
1
1.67 x 10-24
4
Structure of the Atom
There are two regions
The nucleus (not a particle)
• With protons and neutrons
– Positive charge
– Almost all the mass
Electron cloud (mostly empty space)
– Most of the volume of an atom
– The region where the electron(s) can be
found
Football Field Analogy
5
Size of an atom
• Atoms are incredibly tiny.
• Measured in picometers (10-12 meters).
– Hydrogen atom, 32 pm radius.
• Nucleus tiny compared to atom.
– Radius of the nucleus near 10-15 m.
– Density near 1014 g/cm3.
6
Counting the Pieces
= number of protons
# of protons determines kind of atom
Atomic Number = number of electrons in a
NEUTRAL atom
= the number of protons +
neutrons
7
Symbols
Contain the symbol of the element, the
mass number and the atomic
number
# protons
+ # neutrons
mass number
# protons
Mass
number
Atomic
number
X
8
Symbols
• Find the
– number of protons =
– number of neutrons =
– number of electrons =
– Atomic number =
– Mass number =
19
9
F
9
Symbols
Find the
– number of protons =
– number of neutrons =
– number of electrons =
– Atomic number =
– Mass number =
80
35
Br
10
Symbols
If an element has an atomic number of
23 and a mass number of 51 what is
the
– number of protons =
– number of neutrons =
– number of electrons =
– Complete symbol
51
23
V
11
What happens if…
• … the # of p+ changes?
– ex. Helium “gets” 1 more proton
• … the # of e- changes?
– ex. Chlorine “gets” 1 more electron
• … the # of no changes?
- you get a new isotope of that same
atom. Still the type of atom but reacts
a little slower or faster.
12
Isotopes
• Atoms of the same element with
different mass numbers.
• Nuclear symbol:
Mass #
12
Atomic #
6
• Hyphen notation: carbon-12
C
13
Isotopes
Neutron
+
Electrons
Nucleus
+
+
+
+
+
Nucleus
Proton
Proton
Nucleus
Carbon-12
Neutrons 6
Protons
6
Electrons 6
+
+
+
+
Neutron
Electrons
+
+
Carbon-14
Neutrons 8
Protons
6
Electrons 6
Nucleus
14
17
Cl
Isotopes
• Chlorine-37
– atomic #:
– mass #:
– # of protons:
– # of electrons:
– # of neutrons:
37
17
Cl
15
Using a periodic table and what you know about atomic
number, mass, isotopes, and electrons, fill in the chart:
Element
Symbol
Atomic
Number
Mass
Number
# of
protons
# of
neutron
# of
electron
8
8
8
39
Potassium
+1
Br
45
30
charge
65
-1
30
Atomic Number = Number of Protons
Number of Protons + Number of Neutrons = Mass Number
Atom (no charge) : Protons = Electrons
Ion (cation) : Protons > Electrons
Ion (anion) : Electrons > Protons
16
Using a periodic table and what you know about atomic
number, mass, isotopes, and electrons, fill in the chart:
ANSWER KEY
Element
Symbol
Atomic
Number
Mass
Number
# of
protons
# of
neutron
# of
electron
charge
Oxygen
O
8
16
8
8
8
0
Potassium
K
19
39
19
20
18
+1
Bromine
Br
35
80
35
45
36
-1
Zinc
Zn
30
65
30
35
30
0
Atomic Number = Number of Protons
Number of Protons + Number of Neutrons = Mass Number
Atom (no charge) : Protons = Electrons
Ion (cation) : Protons > Electrons
Ion (anion) : Electrons > Protons
17