Transcript protons and neutrons

Atomic Structure
Atomic Structure:
• Location: Where it is on the atom
• Charge: Electric charge (positive, negative or
neutral)
• Mass: how big or small it is
Parts of the Atom:
NUCLEUS
• The small center part of the atom that
contains the neutrons and protons
• from Greek “karyon”, meaning kernel
• Protons and neutron are
packed very tightly!
• The density is the same
as having the entire
mass of the sun
squeezed into Chicago!
Parts of the Atom:
ELECTRON CLOUD
• The large region around the nucleus that
contain the traveling electrons
• 100,000 times larger in
diameter than the
nucleus!
• Impossible to determine
the exact location of an
electron within the
cloud.
Parts of the Atom:
PROTON
• Location: the center of the atom
• Charge: positive
• Mass: About 1 a.m.u, almost 2000 times
larger than the electron, slightly smaller
than the neutron
PROTON
From Greek From suffix “ion”
meaning
“Protos”
meaning first subatomic particle
Parts of the Atom:
NEUTRON
• Location: the center of the atom
• Charge: neutral
• Mass: about 1 a.m.u., almost 2000 times
larger than the electron, slightly larger than
the proton
NEUTRON
From the
noun
“neutral”
From suffix “ion”
meaning
subatomic particle
Parts of the Atom:
ELECTRON
• Location: the outer part of the atom,
surrounding the nucleus
• Charge: negative
• Mass: almost 0 a.m.u., almost 2000 times
smaller than the proton and neutron.
ELECTRON
From the
word
“electric”
From suffix “ion”
meaning
subatomic particle
Comparing Locations:
 Electrons are on the outside of the
atom. They spin around the nucleus in
an electron cloud.
 The protons and neutrons are packed
tightly together in the center of the
atom.
 The space between the electron cloud
and nucleus is huge!
 If the nucleus was the size of a golf
ball, the electron cloud would be 1.5
miles away!
Comparing Charges:
 Electrons have a negative charge, protons have a
positive charge and neutrons have no charge.
Comparing Mass:
 Protons and Nuetrons are almost 2000 times larger than
electrons
Electron (so tiny,
you can’t see it)
If a proton was the size of the blue sphere on the left, then the
electron would be one pixel of the screen—so small, that you
can’t see it! Click here to see website showing this.
Getting Smaller….
 We now know that matter is made up of even smaller matter:
Particles in various combinations
Quarks
up
Leptons
charm
electron
muon
electron
neutrino
muon
neutrino
tau
top
down
strange
bottom
tau neutrino
Up and Down Quarks
3 quarks (up + up + down) make up a proton
3 quarks (down + down + up) make up a neutron
electron
proton
neutron
Bohr Model of a HELIUM ATOM
Shell
proton
+
electron
N
N
+
-
neutron
Question: What are some limitations of this model?
Answer: Electrons are too large and not in an electron
cloud, electrons are too close to the nucleus.
ATOMIC STRUCTURE
Particle
Charge
Mass
Location
proton
+ ve charge
1
nucleus
neutron
No charge
1
nucleus
electron
-ve charge
nil
shell
ATOMIC STRUCTURE
Electrons are arranged in Energy Levels or
Shells around the nucleus of an atom.
•
first shell
a maximum of 2 electrons
•
second shell
a maximum of 8 electrons
•
third shell
a maximum of 8 electrons
Nucleus
Contains protons and neutrons
1st shell
Can hold up to 2 electrons
2nd shell
Can hold up to 8 electrons
3rd shell
Can hold up to 8 electrons
Adapted from http://www.sciencespot.net/Media/atomsfam.pdf
Analyzing Elements on the Periodic Table
4
Be
9.012
Beryllium
Atomic number
the number of protons in an atom
Element Symbol
1, 2 or 3 letters. First letter always
capitalized, second always lower case.
Atomic Mass
the number of protons and
neutrons in an atom
Element Name
*
*
Number of electrons = number of protons
Number of neutrons = Atomic Mass (rounded to nearest) – Atomic Number
So let’s try it….
 How to draw a Lithium atom
 First, look at the Periodic Table
 Second, determine the number of protons
(Look at the atomic number)
 Then determine the number of neutrons
(Atomic mass – atomic number)
 Then determine the number of electrons
(Look at the atomic number)
3
Li
Lithium
7
Created by G.Baker www.thesciencequeen.net
Protons = 3
3
-
Li
+
+
+
-
Lithium
-
7
Electrons = 3
Neutrons = 4
2 in the 1st shell, 1 in the
2nd shell
(7-3=4)
Created by G.Baker www.thesciencequeen.net