This document provides an overview of 8th grade science concepts related to the structure of matter and states of matter. It explains that all matter is made of particles that vibrate with different amounts of energy depending on their state. Solids have particles with high attraction that vibrate in place, while liquids have less attraction allowing particles to slide past each other, and gases have particles moving independently with empty space between them. Phase changes between solid, liquid and gas are also summarized, including that they require gaining or losing energy and have specific melting, freezing, boiling, and evaporation points or conditions. The document concludes with summaries of atomic structure including electrons, protons, neutrons and energy levels, as well as ionic, covalent and

1. STAR Testing Review
8th Grade Science
Structure of Matter
Periodic Table

2. Solids, Liquids and Gases
STATES OF MATTER!!!

3.  All matter is made of atoms and
molecules, which we will call particles.
 All particles vibrate or move because they
have energy.
 The state of matter they are in depends on
how strongly they are attracted to each
other.

4.  Matter that has defined shape and volume
is considered to be solid.
 Particles in a solid have high attraction for
each other. The particles vibrate in place
and don’t have enough energy to get away
from each other
 Two types of solids:
 Crystalline – particles in a repeating formation
 Amorphous – randomly oriented particles

5.  A solid has defined space and volume. It
will not take the shape of the container
unless energy is expended to make it a
different shape.

6.  Liquids have defined volume but not defined
shape
 The particles in a liquid can slide past each
other, and are less attracted to each other than in
a solid.
 Two properties of a liquid:
 Surface tension – the liquids tend to ball up and stick
together
 Viscosity – a measure of how well the liquid flows.
Water is low viscosity, molasses is high viscosity.

7.  A liquid has defined volume but will take
the shape of the container.
 They have more energy than a solid

8.  Gases have no defined shape or volume.
They can be compressed by pressure and
change their volume and will fill all the
space they are given.
 The particles in a gas are moving fast
enough to break away from each other and
each particle moves independently.
 In a gas, there is empty space between
particles.
 Pressure can effect all gases. High pressure
means that you have forced a large amount of
gas particles in a small space – like inside a
tire or basketball.
Gases

9. Phase Change!!!!
Solid--> Liquid--> Gas-->and back!

10. What IS phase change??
 Phase change is the change of the state (solid, liquid, gas)
that the matter is in.
 This change begins by either taking away energy or adding
energy to the particles of matter.
 These changes can start at any state and end at any state.

11. Melting!
 Melting involves ANY solid becoming a
liquid.
 Melting is ENDOTHERMIC- energy in the
form of heat is ENTERING the reaction.
 The molecules are gaining enough energy
to break away from their rigid structure and
move among the group.

12. Melting!
 Every substance has a “melting point”.
 The melting point is the temperature at
which the substance begins to melt.
 The melting point of a substance is a
physical property.
 **ALL substances have DIFFERENT
melting points! It’s not all the same as
water!!!!!!!

13. Freezing
 Freezing involves ANY liquid becoming
a solid.
 Freezing is an EXOTHERMIC reaction-
energy is EXITING the reaction in the
form of heat (heat is leaving).
 The molecules are losing energy- and
forced to stay in a rigid structure.

14. Freezing
 Every Substance has a “freezing point”
 The freezing point is the temperature
where the substance begins to freeze or
solidify.
 The freezing point of a substance is a
physical property and varies for each
substance.

15. Condensation
 Condensation is when a gas becomes a
liquid.
 This is an EXOTHERMIC reaction-
energy LEAVING in the form of heat.
 The molecules are losing energy and
become a group again after being totally
independent.

16. Vaporization
 Evaporation is any liquid becoming a gas
 This reaction is ENDOTHERMIC-
energy is ENTERING in the form of
heat!
 The molecules are gaining SO much
energy that they are becoming totally
independent and fly away on their own!

17. Vaporization
 There are two types:
 Boiling
 Evaporation

18. Boiling
 Boiling is…
 a relatively quick change from a liquid to a gas
 Occurs by adding a lot of heat all at once
 Happens at a specific temperature
 The change happens within the ENTIRE fluid-
all molecules are being affected.

19. Evaporation
 Evaporation is…
 A relatively slow process
 Occurs overtime from gas particles crashing
onto the surface of the liquid and passing on
their energy to the liquid molecules.
 No specific temperature associated with this
change (can happen at room temp!)
 Happens only on the surface of the liquid.

20.  Particles in a gas state are not bound to each
other and have the most energy.
Example of a Gas

21. The parts of an Atom

22. The atom
 An Atom: The most basic unit of matter.
 An atom has a dense nucleus and a cloud of
negatively charged electrons around it.
 If matter is what everything is made of, and
matter is made of atoms…
 Then, everything is really made of atoms!

23. The Parts:
 Electron: A subatomic particle with a negative
electrical charge. (no mass)
 Nucleus: The dense center of an atom
containing protons and neutrons.
 A Proton: A subatomic particle within the
nucleus of an atom that has a positive charge.
 A Neutron: A subatomic particle within the
nucleus of an atom that has a neutral charge.

24. Energy Level
 The energy level of an atom is as follows:
 2,8,8
 The first shell has two electrons
 The second shell has 8 electrons
 The third shell has 8 electrons
MEMORIZE: 2,8,8!!!!!!!!!!

25. Atomic Number
 The atomic number is the
number mainly associated
with the element and
represents the number of
protons present in the
atom.

26. Mass Number
 The total number of
protons and neutrons.
 The mass of an atom comes
from the protons and
neutrons.
 Therefore, the mass includes
the masses of each added
together.
 This number can be found at
the bottom, typically.
Mass Number

27. Element
 Each of these are ELEMENTS!!!
 When you put them together, they become
something different…

28. Compounds!
 Remember that compounds are merely the
result of combining two or more elements.
 H2O is a compound! NaCl is a compound!
 REMEMBER- compounds have different
properties than the elements they are made
of when alone.
 Hence why table salt (NaCl) doesn’t blow up

29. How can you identify Elements?
 What are the elements in the following
compounds?
 H2O
 NaCl
 CO2

30. Periodic Table!!
 Remember that beautiful display of
elements?
 It’s time to remember how to use it!

31. Time to test your knowledge!
 How many groups are there?
 Which group number are the noble (inert) gases?
 Why are the noble gases important?
 Where are the metals located?
 Where are the semi-metals?
 Where are the Alkali metals located?
 Where are the Alkaline Earth metals located?

33. Review of Chemical Bonding
Ionic, Covalent, Metallic

34. Ionic Bonds
 Ionic Bonds occur between metals and non-
metals.
 Metals always lose their extra valence
electrons and non-metals always try to gain
extra valence electrons.
 Metals become positive ions and non-
metals become negative ions.

35. Ionic Bonds
 Properties of Ionic Bonds:
 Brittle (breaks easily)
 Extremely high melting and boiling points
 Conduct electricity
 Form between ions (metals & non-metals)

36. Covalent Bonds
 Covalent bonds occur between non-metals
and non-metals
 Since non-metals are always trying to find
extra electrons rather than get rid of them,
Covalent bonds always share their electrons
(how nice of them!)

37. Covalent Bonds
 Properties of Covalent Bonds
 Malleable (can be formed/manipulated)
 Low melting and boiling points
 Do not conduct electricity or heat

38. Metallic Bonds
 Metallic bonds occur between metals and
metals.
 Remember that all metals are always trying
to lose their extra electrons to become
happy.
 In Metallic bonds metals “pool” their
electrons and all become ions while
“swimming” around in the pool of electrons
(AKA the “sea of negativity”)

39. Metallic Bonds
 Properties of Metallic Bonds:
 Malleable
 Ductile (can be stretched into wires)
 Conducts heat and electricity