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

Solids, Liquids and Gases STATES OF MATTER!!!

 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.

 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

 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.

 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.

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

 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

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

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.  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.

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.  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.

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!!!!!!!  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!!!!!!!

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.  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.

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.  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.

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.  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.

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!  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!

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

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.  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.

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.  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.

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

The parts of an Atom

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!  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!

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.  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.

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!!!!!!!!!!  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!!!!!!!!!!

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

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.  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

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

Compounds!  Remember that compounds are merely the result of combining two or more elements.  H 2 O 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  Remember that compounds are merely the result of combining two or more elements.  H 2 O 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

How can you identify Elements?  What are the elements in the following compounds?  H 2 O  NaCl  CO 2  What are the elements in the following compounds?  H 2 O  NaCl  CO 2

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

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?  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?

Review of Chemical Bonding Ionic, Covalent, Metallic

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.  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.

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

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!)  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!)

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