Download What is Matter?

Structure of Matter
8th Grade Science
Vocabulary Terms
Atom
 Electron
 Law of Conservation of Matter
 Matter
 Neutron
 Nucleus
 Proton

WHAT IS MATTER?
Is this glass half empty or half full?
Neither is
CORRECT!
WHAT IS MATTER?
The glass is FULL!
•Half of the glass is full of water
•The other half is full of air
•What is air?
•Air is a mixture of several
gases
•Mostly made up of
Nitrogen and Oxygen
What is Matter?

Nitrogen and Oxygen are kinds of matter.
◦ Matter is anything that has mass and takes up
space.
 You cannot hold or see air, but it is still
matter.
 We know air is not there when we cannot
breathe.
Matter

Water is also matter
◦ Most of the things you can see, taste, smell,
and touch are made of matter.
◦ Name other things that are matter:
What is NOT matter?

You could not see what was going on
around you without light.
◦ Light has no mass and does not take up space.
 So light is NOT matter.

Is heat matter?
◦ Heat also has no mass and does not take up
space.
 So heat is not matter.

Your thoughts, feelings, and ideas are not
matter
What makes up matter?

I take wood from a tree and run it
through a saw.
◦ Is it still wood?

I take the sawed piece of wood and put it
into a chipper.
◦ Are the chips still wood?

I take the wood chips and grind them into
saw dust.
◦ Is the saw dust still wood?
Matter
How far can I break down saw dust
before it is no longer smaller versions of
wood?
 All matter eventually breaks down to
their atomic structure.

◦ No atom can be broken down into something
smaller.
In your Science
Notebook…Answer the
following:
List 3 things that
are NOT matter.
List 3 things that
are matter.
Use Your Noodle Time!
Time: 5 Minutes
Ideas of matter.

Greek philosopher – Democritus
◦ (460 B.C. to 370 B.C.)
◦ Thought the universe was made of empty space
and tiny bits of stuff called atoms.
◦ Atom comes from the Greek word that means
“cannot be divided”.
 Believed atoms couldn’t be broken down into smaller
pieces.
 Definition of atom: An atom is the basic unit of an element. An
atom is a form of matter which may not be further broken
down using any chemical means. A typical atom consists of protons,
neutrons and electrons.
Democritus’s Ideas About Atoms
1.
2.
3.
4.
5.
All matter is made of atoms.
There are empty spaces between atoms
Atoms are complete solids
Atoms do not have anything inside them
Atoms are different in size, shape and
weight.
Democritus’s Ideas About Atoms
Thought that different types of atoms
existed for every type of matter.
 Thought the different atoms explained
the different characteristics of each type
of matter.

Gold
Silver
Iron
In your Science
Notebook…Answer the
following:
Summarize:
What is an atom?
Use Your Noodle Time!
Time: 5 Minutes
Can matter be made or destroyed?
People thought matter disappeared when
it burned or rusted.
 Seeing objects grow, like trees, also made
people think that matter could be made.

Lavoisier

French Chemist
◦ Lived about 2,000 years after Democritus
◦ Lavoisier studied wood fires.
 He showed that the wood and oxygen it combines with
during the fire have the same mass as the ash, gases,
and water vapor that are produced by the fire.
 Matter is not destroyed when wood burns.
 It just changes into a different form.
Law of Conservation of Matter

Lavoisier’s work created this law
◦ This law states that matter is not created or
destroyed – matter only changes form.
◦ Example
Total mass of
Wood + Oxygen
=
Total mass of
Ash + Gases + Water Vapor
In your Science
Notebook…Answer the
following:
Use Your Noodle Time!
Apply:
Suppose you
increase the mass
of wood you are
burning in a
fireplace. What
will happen to the
total mass of ash,
gases and water
vapor?
Time: 3 Minutes
Models of the Atom
Models often are
used for things that
are too small or too
large to be observed.
 Models also are used
for things that are
difficult to
understand.

Dalton’s Model
John Dalton was an
English chemist
during the 1800’s.
 His atomic model
was a set of ideas
instead of an object.

◦ Believed matter was
made of atoms that
were too small to see.
Dalton’s Atomic Theory of Matter

He thought that each type of matter was
made of only one kind of atom.
◦ Example:
 Gold bars are made of gold atoms
 Iron rods are made of iron atoms
 The different type of atoms explains why gold and
iron are different.
 Scientists studied Dalton’s model and it became
known as the Atomic Theory of Matter.
In your Science
Notebook…Answer the
following:
Use Your Noodle Time!
Explain:
Dalton’s atomic
model was not an
object.
What was it?
Time: 3 Minutes
How small is an atom?

Atoms are so small that it would take
about 1 million of them lined up in a row
to be about as thick as one human hair.
What is an electron?
An English scientist
named J.J. Thomson
discovered the
electron in the early
1900s.
 He experimented
using a glass tube
with a metal plate at
each end.

Thomson Cathode Ray
Thomson connected
the metal plates to
electricity.
 One plate called the
anode, had a positive
charge.
 The other plate, called
the cathode, had a
negative charge.

Thomson’s Cathode Ray
During his
experiments,
Thomson watched
rays travel from the
cathode to the
anode.
 Then he used a
magnet to bend the
rays.

Thomson’s Cathode Ray
Since the rays could be bent, they were
made of particles that had mass and
charge.
 He knew that like charges repel and
opposite charges attract.
 Since the rays were traveling to the
positive plate, Thomson decided the rays
must be made of particles with a negative
charge.

Thomson’s Cathode Ray
These invisible particles with negative
charges are electrons.
 Thomson showed that atoms can be
divided into smaller particles.

In your Science
Notebook…Answer the
following:
Use Your Noodle Time!
Explain:
Why was
Thomson’s
discovery
important?
Time: 3 Minutes
What was Thomson’s model of the
atom?
Matter that has an equal amount of
positive and negative charge is neutral
 Most matter is neutral
 So, Thomson thought an atom was made
of a ball of positive charge with negatively
charged electrons in it.

Thomson’s model
His model of an atom was like a ball of
chocolate chip cookie dough.
 The dough was positively charged.
 The chocolate chips were the negatively
charged electrons.

In your Science
Notebook…Answer the
following:
Use Your Noodle Time!
Explain:
What did
Thomson think
an atom was
made of?
Time: 3 Minutes
WHAT WAS
RUTHERFORD’S MODEL
OF THE ATOM?
Scientists still had questions about how the
atom was arranged and about particles with
positive charge.
 Around 1910, English scientist named Earnest
Rutherford and his team tried to answer
these questions.

Rutherford’s Experiment

Rutherford’s team shot tiny, high-energy,
positively charged particles (aka Alpha
Particles) at a very thin piece of gold foil.
◦ They thought the alpha particles would pass
easily through the foil
◦ Most did pass straight through
◦ But, other alpha particles changed direction.
 A few of them even bounced back.
Gold Foil Experiment
Rutherford’s Experiment
Since most particles passed straight
through the gold, he thought that the gold
atoms must be made of mostly empty
space.
 But, because a few particles bounced off
something, the gold atoms must have
some positively charged object within the
empty space.

Rutherford’s Experiment

He called this positively charged object
the nucleus.
◦ The nucleus is the positively charged, central
part of an atom.
◦ Rutherford named the positively charged
particles in the nucleus of the atom protons.
◦ He also suggested that negatively charged
electrons were scattered in the empty space
around the nucleus.
Bonus Points!!
There are 3 parts of
an atom…
Rutherford was able
to explain the
Protons and
Electrons.
You have ONE Minute!!
Do you know what
part of the atom
Rutherford did not
find?
How was the neutron discovered?

Rutherford was puzzled by one
observation in his experiment with alpha
particles.
◦ The nucleus of an atom seemed to be heavier
after the experiment.
◦ He did not know where this extra mass came
from.
Neutron
James Chadwick, one of Rutherford’s students,
answered the question: the nuclei were not
getting heavier.
 But, the atoms had given off new particles.



He found that the path of the new particles was not
affected an electric field.
This meant that new particles were neutral – had no
charge.
Neutron

Chadwick called these new particles
neutrons.
◦ A neutron is a neutral particle in the nucleus
of an atom
◦ This proton-neutron model of the nucleus of
an atom is still accepted today.
Question your Science
Notebook…Answer the following:
Explain:
Question #1:
In Rutherford’s
model, what is an
atom mostly
made of?
Use Your Noodle Time!
Question #2
What type of
charge do
neutrons have?
Time: 5 Minutes
Improving the Atomic Model

A scientist named Niels Bohr found that
electrons are arranged in energy levels in
an atom.
◦ He found that there is a maximum number of
electrons that can be held in layers around
the atom.
 Example
 1st layer can hold no more than 2 electrons
 2nd layer can hold no more than 8 electrons
 3rd layer can hold no more than 18 electrons
What is the modern atomic model?
Today, scientists realize that electrons
have characteristics similar to both waves
and particles.
 So, electrons do not orbit the nucleus of
an atom in paths.

◦ Instead, electrons move in a cloud around the
nucleus.
Electron Cloud
Best song in the world!
Question your Science
Notebook…Answer the following:
Compare and
Contrast:
How is Bohr’s
atomic model
different from the
modern atomic
model?
Use Your Noodle Time!
Time: 5 Minutes
REVIEW!
Answer the following in your Science Notebook.
1.
Explain the law of conservation of matter.
2.
How could you explain the modern atomic
model to another student?
You have 6 Minutes!
FILL IN EACH BLANK IN THE CONCEPT MAP.
Matter is made of
that have a
Nucleus
that has
and