1. Atoms, Molecules and extended Structures
Physical Science
Atoms, Molecules and extended Structures

2. Atomic Structure Review: What is matter?
Anything that has mass and takes up space
Atom: smallest piece of matter than has the properties of an element
Element: substances that are made up entirely of one kind of atom, pure substances with distinct properties that DO NOT vary
Scale: size, extent or importance (magnitude) of something relative to something else
Just how small is the atom?
Lets talk about scale and the atom….
Think about the atoms that make up a grapefruit
If each atom were the size of a blueberry, the grapefruit would be the size of the EARTH!!!!!

3. Atomic Structure
Atoms are made up of smaller (subatomic) particles called
Protons- (+) charge, found in nucleus
Neutrons- no charge or neutral, found in nucleus
Nucleus: region at the center of the atom, positively charged, very dense
99.9% of the mass of the atom comes from the protons and neutrons
Electrons- (-) charge, found in electron cloud outside of nucleus
Much smaller than protons and neutrons, in constant motion
The subatomic particles are MUCH smaller than the atom itself, most of the atom is empty space
Back to our blueberry comparison….
If the atom was a blueberry and you opened it up, the nucleus (containing the protons and neutrons) would be too small to see
If you were to make the blueberry the size of a football field you would just be able to see the nucleus—it would be the size of a marble

4. Atomic Structure
Scientists never work with single or individual atoms because they are too SMALL
Instead they work with elements
The structure of the atom (#of protons, neutrons, or # and/or arrangement of electrons) gives the element its particular properties
Each element on the period table has a symbol
Atomic number = number of protons or the number of electrons, like the ID number for the atom. This defines the atom
Hydrogen will always only have atomic number 1, one proton
Helium (He) will always only have the atomic number 2, two protons
Atomic mass = protons plus neutrons

5. Atomic Structure
Bohr Diagram – a diagram that accounts for all of the electrons an atom has
How to draw a Bohr Diagram
Energy level – represents the space around the nucleus where the electrons are expected to be
1st energy level – can hold two electrons
2nd energy level – can hold 8 electrons
3rd energy level – can hold 8 electrons
Time to practice, lets draw a few Bohr Diagrams 
Valence Electrons – those electrons on the outer most energy level
Lewis Structure (AKA Electron Dot Diagram) – a diagram that accounts for only the VALENCE electrons
Time to practice, lets draw a few 

6. Atomic Structure The Periodic Table
Organized by atomic number
An element’s place on the periodic table indicates the following
Some of its properties
How reactive it is
If it’s a metal, non metal or, metalloids
Metal- shiny, malleable, good conductor
Non metal- brittle, dull, and poor conductors
Metalloids- have properties of both metals and non metals, semi conductors
Shiny and hard but brittle
Periods – rows in the periodic table
Group or Family – column in the periodic table
Those elements in a group/family have similar properties

7. Energy Changes and Matter
To understand how scientists create new materials with specific properties for specific purposes we must understand the relationship between matter and energy.
Matter can only change when enough energy is present
Two main types of energy
Kinetic energy- energy of motion
Potential energy – stored energy due to position or shape
Thermal Energy – a type of kinetic energy
Temperature is a measurement of thermal energy
The faster the atoms move, the more thermal energy they have, the greater the temperature
The amount of thermal energy present in a substance determines whether that substance is a solid, a liquid or a gas
Change of state is considered a physical change
Physical change - a change in one or more physical properties of matter without any change in chemical properties
Caused by cutting, bending, dissolving, freezing, boiling
States of Matter Video

8. Energy Changes and Matter
Chemical Energy – potential energy stored in the bonds that hold atoms
and molecules together; it allows new molecules and compounds to form
Compound – combination of two or more different kinds of atoms bonded together
Water (H2O), Carbon Dioxide (CO2)
Molecule – made up of two or more atoms bonded together, can be small or large
Water (H2O), Carbon Dioxide (CO2), Oxygen (O2)
All compounds are molecules, but not all molecules are compounds
Molecules vary in size, can be small can be large
Water (H2O), small only three atoms
Vitamin C = (C6H8O6) 20 atoms
Chemical reaction- atoms that make up
reactants (original substances) are rearranged
into products (new substances) that have
different properties from the original substances
Chemical reactions are based on chemical
changes
Evidence of a chemical change/reaction = bubbles
are released, there is a change of color, or an odor is
produced. Other clues include the release of heat, light,
or loud sounds

9. Energy Changes and Matter
Chemical Reactions (cont.)
When reactants come together, energy breaks the bonds that hold reactants together and rearranges the atoms and molecules to form new products
Chemical reactions obey the law of conservation of mass
Matter is never created or destroyed
The total number of atoms does not change in a chemical reaction
Mass of any one element at the beginning of the reaction will equal the mass of that element at the end of the reaction
Two types of chemical reactions
Endothermic – more energy is needed to break the bond of the reactants than is released when new bonds form
Ice Pack
Exothermic - more energy is released when new bonds form in the products than is needed to break bonds in the reactants
Striking a match, bioluminescence
Endothermic/Exothermic video
Exothermic Experiment video