Download + Atomic

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Atomic Structure
Ms. Nail: 7th and 8th Grade Science
WHAT is an Matter?
MATTER is: Anything that has mass and takes up space. Matter is
every thing around you.
What are the 3 States of Matter?
1. SOLID: Matter with a definite shape and volume. The particles are
close together and vibrate.
2. LIQUID: Matter that has definite volume but no definite shape.
The particles are further apart , and can move freely.
3. Gas: Matter that does not have a definite shape or volume. The
particles are spread apart and move at high speeds in all
directions.
So….What is an ATOM anyway?
An ATOM is a small particle that is a building block of all matter.
What are the 3 particles that an atom is made of?
1. PROTONS
2. NEUTRONS
3. ELECTRONS
1. Protons (+)
 Positively
particles
charged
 Heavy
particles, makes
up half the mass in an
atom.
 Found
in the nucleus of
the atom
to the atomic
number of the atom
++ +
+++
+ +
-
-
 Equal
 Equal
to the number of
electrons
-
+
-
2. Neutrons (-)
-
-
 Neutral
++ +
+++
+ +
-
-
-
particles;
have no electric
charge
 Heavy
particle,
makes up half the
mass in an atom.
 Found
in the
nucleus of the atom
A NEUTRON WALKS INTO A
RESTAURANT AND ASKS, HOW
MUCH FOR A COKE?
THE WAITRESS REPLIES,
FOR YOU, NO CHARGE!!
GET IT?
NO
CHARGE?
The POSITIVE charge on PROTONS (+) and NEGATIVE charge on
ELECTRONS (-) cause the two to be ATTRACTED to each other and
CANCEL each other out.
This attraction is what holds an atom TOGETHER (similar to a magnet).
3. Electrons (-)


-
Negatively charged particles
Found outside the nucleus of
the atom, in the electron
orbits/energy levels

Move so rapidly around the
nucleus that they create an
electron cloud

Very light and adds almost no
mass to the atom but is
responsible for the volume in
an atom.

Equal to the number of protons
++
+ ++
+
+ +
-
-
-
-
-
-
Valence Electrons
What is a VALENCE ELECTRON?
An electron that is found on the OUTERMOST energy level/shell. Valence
electrons are responsible for BONDING.
The number of valence electrons can range anywhere from 1 to 8 on the
OUTERMOST energy level, depending on what PERIOD they are found
on, on the PTE.
Valence electrons can be SHARED or GIVEN AWAY.
Orbitals/Energy
Levels/Shells
ELECTRONS are found in areas called SHELLS. A shell is
sometimes called an ENERGY LEVEL OR ORBITAL.
Shells are RINGS that surround the CENTER of an atom.
ENERGY LEVELS
+
Atomic Number
 The
number of protons in the nucleus of an atom
-
-
+
++
What would be the
atomic number of
this atom?
-
+
ATOMIC MASS

The total number of protons and neutrons in an atom’s nucleus

Expressed in Atomic Mass Units (amu)
 Each proton or neutron has a mass of 1 amu
What would be the mass
number of this atom?
+
-
 3
+
++
 4
3 protons + 4 neutrons =
a mass number of 7 amu
Why did we not account for the
electrons when calculating the
mass number?
-
-
+
When trying to remember all of those
rules when calculating the
Atomic Structure of an Atom, just
remember THIS:
Atomic Number
is the same # of
Protons
is the same # of
Electrons
Mass Number
minus -
Atomic Number
=‘s # of
Neutrons