Download - MrKowalik.com

Atoms
Review:
• Matter is anything that takes up space (has
volume) and has weight (has mass).
What is most matter made of?
• Most matter is made up of molecules.
What are molecules made of?
• Molecules are made of ATOMS.
So what’s an atom??
• An atom is the smallest unit that all matter is
made up of.
• Atoms are the building blocks of matter, sort of
how bricks are the building blocks of houses.
A closer look at an atom
• An atom has three parts:
Protons
= positive charge (+)
Neutrons = neutral (no) charge (+/-)
Electrons = negative charge (-)
The protons & neutrons are found in the
center of the atom, a place called the
nucleus.
The electrons orbit the nucleus
Atomic Fact # 1:
• No matter is made up of protons alone.
• No matter is made up of neutrons alone.
• No matter is made up of electrons alone.
• In other words…..no matter is made unless
these parts are joined together to make up an
atom. It’s the atoms that build matter, not the
atom’s parts alone.
Atomic Fact # 2:
• The number of protons ALWAYS equals the
number of electrons..
So what does that mean about
the charges?
• The number of positive charges ALWAYS
equals the number of negative charges in an
atom.
So then what kind of charge do
atoms have?
• Atoms have a neutral charge (no charge) since
they have equal amounts of positive and
negative charges.
Atom Models
There are two models of the atoms:
• Bohr Model
• Electron Cloud Model
Although the Electron Cloud Model is the most
recent model, in class we will be using the Bohr
model since it shows important information about
the electrons.
Bohr Model
• The Bohr Model shows
all of the particles in the
atom.
• In the center are circles.
Each circle represents a
single neutron or proton.
Protons should have a
plus written on them.
Neutrons should be
blank.
• In a circle around the
nucleus are the
electrons. Electrons
should have a minus
sign.
-
+
+
-
Electrons have special rules….
• You can’t just shove all of the electrons into the
first orbit of an electron.
• Electrons live in something called shells or
energy levels.
• Only so many electrons can be in any certain
shell.
• The outer most shell is called the valance
shell.
• The electrons in the outer most shell of any
element are called valance electrons.
Nucleus
1st shell
2nd shell
3rd shell
So let’s draw this in our
notebooks….
Since atoms are so small, is it
easy to break them apart?
• No. The forces holding atoms together are
extremely strong (which is good because if they
were weak then everything we know that’s
matter could fall apart easily).
• Breaking open an atom’s nucleus releases
energy from that nucleus called nuclear energy.
• Nuclear energy is extremely powerful and is
used in making nuclear weapons.