Lesson teaches students about Matter (grades 6-8) & talks about the atomic models & the history behind the way it has been established through physics.
This Lesson Also Includes:
1. Physical & Chemical Changes
2. States of Matter & Phase Changes in Matter
3. Molecular Movements in a Solid, Liquid, & Vapor
2. Matter
Matter describes everything that we can see, touch, smell, or feel. In other
words, matter is anything that has mass & takes up space (including air &
almost everything else).
matter: anything that has
mass & takes up space
3. Atoms
The smallest unit of matter is called an atom. If you chop a piece of
metal into a bajillion pieces, the smallest bit you are left with that
still has the properties of the metal is called an atom.
atom: the smallest unit of
matter
The word atom is
derived from a Greek
word that means
¨cannot be divided¨.
4. Atomic Models
Atoms are made of smaller particles:
Protons (positively charged particles)
Neutrons (electrically neutral particles, which means they have
no change)
Electrons (negatively charged particles with almost no mass)
5.
6. Nucleus (In Atoms)
Protons & neutrons stick together to form the center of an atom, called the
nucleus, which has a net positive charge. Electrons orbit, or circle around,
the nucleus, but too quickly to pinpoint their exact locations.
nucleus: the center of an atom,
formed by protons & neutrons
7. Modern Atomic Model & Electron Cloud
The Modern Atomic Model shows an Electron Cloud rather than
individual electrons like the model below. It demonstrates where
you´re most likely to find an orbiting electron. Denser areas of the
cloud means a high probability of electrons.
8. Brief History of the Atomic Models: John
Dalton
John Dalton was the first scientist to propose that elements are
composed of indestructible atoms. He thought that there were particles
so small that we could not see them. He called these particles atoms, &
his theory of matter was known as the Atomic Theory of Matter.
9. Sir Joseph John (J.J.) Thomson
Sir Joseph John (J.J.) Thomson discovered the prescene of negatively
charged particles (electrons) in atoms & pictured them embedded
with positively charged particles, kind of like raisins in oatmeal-raisin
cookies.
10. Ernest Rutherford & Sir James Chadwick
Ernest Rutherford worked out that each atom had a small & heavy
positively charged center, which he called a nucleus. He figured out
that electrons were orbiting the nucleus in mostly empty space. He
called the positive particles in the nucleus protons. Rutherford´s
student Sir James Chadwick proposed the existence of uncharged
particles in the nucleus, which he called neutrons.
11. Physical & Chemical Properties & Changes
The way something feels, looks, smells, & tastes are all physical
properties. It´s easy to classify matter by these characteristics.
Some common physical properties used to differentiate matter
are:
12. Color, SIZE, DENSITY
malleability: (how easily something can be flattened, shaped, or
pressed)
magnetism: (whether or not something is magnetic)
Boiling Point & Melting Point (the temperature at which
something boils or melts)
solubility: (how easily something dissolves in another substance)
13. Physical Changes
A physical change is any change to the physical properties of matter
such as its size, shape or state (solid, liquid, or gas/vapor). The final
product of any physical change is still composed of the same matter.
For example, you can revert ice, snow, & vapor back to water by either
heating or cooling it. Ice, vapor, & water are all the same matter - just
in different states.
15. Examples of Chemical Properties:
flammability (how easily something lights on fire)
reactivity (how reactive something is to oxygen, water, light,
etc.)
16. Chemical Change
When any of those chemical properties changes, the matter has
gone through a chemical change. Rust on an iron gate or a log
burning & producing ashes are both examples of chemical
changes. Some signs of chemical change may include:
17. Examples of Chemical Changes
Change in Color - This is like when you leave a sliced apple out & it
turns brown
Change in Energy - The chemicals react, releasing energy in the form of
bright lights & heat
Change in Odor - This is like when food becomes rotten.
18. Examples of Chemical Properties
Formation of a Gas or Solid - When you add 2 substances together, such
as vinegar & baking soda, you frequently see bubbles. Bubbles, or gas
formation, are a sign that the ingredients have undergone a chemical
change.
19. Chemical Properties (continued)
Chemical changes are often much harder to reverse than physical
ones - just imagine trying to turn ashes back into a log of wood.
20. Synthetic Materials
Synthetic Materials are materials that don´t occur to nature, but are
instead made from natural resources that undergo a chemical change.
For example, polyester is a synthetic fiber made from air, water, coal,
& petroleum. Acid & alcohol are used to create a chemical reaction,
which results in polyester fibers.
21. Conservation of Mass
While things may change appearance or composition during physical &
chemical changes, 1 thing remains consistent: the amount of matter
present. This concept is called the conservation of mass. So mass doesn´t
just dissapear - it still exists, but it may be in a different form, like in the
surrounding gases. The atoms have just rearranged to form different
substances.
conservation of mass: the amount of
mass at the start of a reaction will equal
the amount of mass after the reaction
22. States of Matter
Matter is usually found in three states (or phases): solid, liquid, & vapor (or
gas). The arrangement & behavior of particles is what determines the state
of matter. The attraction between particles keeps particles close together, &
the energy of their movement allows particles to overcome these attractive
forces.
23. Solids
A solid, like ice, wood, or metal, is matter that has a defined shape &
volume. The particles in matter are packed closely together, & they don´t
move around freely, which is why a solid has a defined shape & volume. Still,
particles in a solid vibrate back & forth, but not enough to overcome the
attractive force between particles.
24. Liquids
Liquids are free-flowing & assume the shape of the container that holds
them. Liquids, however, do have a fixed volume. Particles in liquid move
around fast enough to overcome attractive forces. While the liquid particles
do move freely, they still stick together. The speed at which a liquid flows
depends on its viscosity. Viscosity is the resistance to flow.
25. Vapors
Vapors (or Gases) don´t have fixed volume or shape. The shape & volume of
a gas depends on its container, & unlike liquids, it will fill any container you
place it in. The molecules in gases spread really far apart & move at high
speeds. Gas molecules move so quickly that they are able to overcome
attractive forces between particles, which allows the molecules to seperate
on their own. If you spilled the gas from a balloon into the air, it would
disperse evenly into the air.
26. State Features Movement of Particles
Solid Fixed shape &
volume
Vibrate, but have fixed
positions
Liquid
Shape can change,
volume is fixed. Can
flow.
Free-moving; no fixed
positions
Gas
Shape & volume not
fixed & depends on
container. Can flow.
Particles move quickly
& are far apart
27. Phase Changes
A state isn´t permanent. Changes in pressure & temperature alter
matter - these are described as phase changes.
28. Melting
Melting is when matter changes from solid to liquid. The melting point is
the temperature at which a solid melts. Heat causes solids to melt by
increasing the movement of particles. As the particles gain more & more
energy from the heat, they move more & more until they are no longer
fixed in place.
29. Remember!
Above 100 Celsius, water is a vapor.
Between 0 Celsius & 100 Celsius, water is a liquid.
Below 0 Celsius, water is a solid.
30. Freezing
Freezing is when matter changes from liquid to solid. As liquids cool down,
the particles move less and less. At some point, the motion of particles can't
overcome the attractive forces between particles, and the liquid turns to
solid. The temperature at which a liquid freezes is called the freezing point.
31. Vaporization
Vaporization is when liquid turns to vapor. When sweat disappears and
dries up, it has vaporized or evaporated. Evaporation happen slowly &
only at the surface (individual molecules get out into the air). When water
boils, it has reached the temperature at which water turn some liquid to
vapor. Heat causes liquid particles to move around quickly. When the
particles are moving around fast enough to overcome all attractive forces
between particles, the liquid turns to vapor.
32. Condensation
Condensation is when vapor turns to liquid. When you get a really
cold drink, the air around the glass condenses and form little
water droplets on the surface of the glass. When water vapor in
the air cools down and loses energy, the park will start to slow
down. When the particles slow down enough, the attractive
forces between particles cause the molecules in the vapor to stick
together, forming a liquid.
33. Sublimation & Deposition
Sometimes, under extreme conditions, solids can change directly
to vapors, which is called sublimation. Dry ice, for example,
sublimates when the CO2 turns directly into solids, which is called
deposition, like when frost appears on grass overnight.
Notes de l'éditeur
Melting is when matter changes from solid to liquid. The melting point is the temperature at which a solid melts. Heat causes solids to melt by increasing the movement of particles. As the particles gain more & more energy from the heat, they move more & more until they are no longer fixed in place.
Vaporization is when liquid turns to vapor. When sweat disappears and dries up, it has vaporized or evaporated. Evaporation happen slowly & only at the surface (individual molecules get out into the air). When water boils, it has reached the temperature at which water turn some liquid to vapor. Heat causes liquid particles to move around quickly. When the particles are moving around fast enough to overcome all attractive forces between particles, the liquid turns to vapor.
Condensation is when vapor turns to liquid. When you get a really cold drink, the air around the glass condenses and form little water droplets on the surface of the glass. When water vapor in the air cools down and loses energy, the park will start to slow down. When the particles slow down enough, the attractive forces between particles cause the molecules in the vapor to stick together, forming a liquid.
Sometimes, under extreme conditions, solids can change directly to vapors, which is called sublimation. Dry ice, for example, sublimates when the CO2 turns directly into solids, which is called deposition, like when frost appears on grass overnight.
