Physical and Chemical Changes

The Three States of Matter


The three states of matter are: solid, liquid, and gas. Particles behave differently depending on what kind of matter it exists in. Solids are usually stable, with little less vibrations and energy than liquid and gas. Liquids are free-moving, and typically don't stay a certain shape unless within a container. Matter in the form of gas is pretty much everywhere, moving quickly at all times. These are the three main types of matter that makes up our world (well there's plasma but I guess we're not there yet).

Chemical Changes

Chemical changes occur at the molecular level. These changes always involve creating a new compound or substance from the original materials. These changes are difficult to reverse, or even impossible. Combustion is a type of chemical change, and you'd be hard pressed to "unburn" wood logs.

Physical Changes

Physical changes, in contrast with chemical changes, do NOT produce a new substance or compound. Typically, physical changes are changes in state (melting, freezing, etc) or shape (a bent spoon, for example). These changes are much easier to reverse than chemical changes.

What's the Matter?

Matter is everything that has MASS and takes up VOLUME (or space).
It is made up of atoms and molecules which contain mass.

The three units of mass:
gram                 g        
kilogram           kg
milligram          mg       

Example:
A small penny coin has a mass of 2.5g



However, the mass of the M87 black hole can be as much as 3.580056 × 10³¹ kg!



For a grain of sand, it is estimated to have a mass of 2.5mg.




Matter can be seperated into two categories: "Mixture" and "Pure Substance".

Mixture
- Made out of substances that CANNOT be united during any chemical processes
- Have more than one set of properties
- Example: salt water, alcohol
- Can be classified as "Homogeneous" or "Heterogeneous"
               Homogeneous
                  
              
                ↑ Sugar added in a glass of water
              ~Different components are NOT visible to naked eye after being mixed
              ~ The components are spreaded uniformly throughout mixing
             ~ They do not undergo any reactions
             ~ Examples: sugar in coffee, milk in tea

             Heterogeneous

           
             ↑  Oil floating on top of a glass of water
            ~ Different components can be visibly seen after mixed together
           ~ Components seem to have very different properties so they don't blend
           ~ Physical appearence of components will not be changed after mixed
           ~ Examples: oil with water, noodles with pork, sand in water

Pure Substance
- Cannot be physcially or chemically seperated
- Have the same taste, color, composition, and texture between the substances
- Have only one set of properties
- Examples: Gold, oxygen gas
- Can be classified into an "Element" or a "Compound"

          Element
          ~ Composed of atoms
          ~ The simplest form of matter
          ~ Cannot be decomposed or break down
          ~ There are 115 known elements
          ~ Example: hydrogen, nitrogen, silver
          ~ Can classified into "Metal", "Metalloid" and "Non-metal"

                 Metals

                
                ↑ A testube with mercury
              ‧Metal elements are great conductors of heat and electricity
              ‧High melting points
              ‧Solid at room temperature
              ‧Example: iron, copper, silver

                 Metalloid

               
                ↑ Boron, a metalloid
              ‧They have both metal and non-metal properties
              ‧They are like non-metals when they "meet with" metals
              ‧They are like metals when the "meet with" metals
              ‧Example: boron, silicon

                Non-metal

                
                 ↑ Neon is an example of a non-metal
              ‧Heat and electricity isulators
              ‧Gain electrons easily
              ‧Example: neon, chlorine

          Compound
          ~ They are made up of two or more elements
          ~ Compounds are combined chemically
          ~ Molecules such as oxygen gas should composed of 2 atoms
          ~ Example: Chlorine gas, sulfur dioxide       
 
               Ionic-acid
              ‧Has a pH <7
              ‧Corrosive
              ‧Taste sour
              ‧Always have a hydrogen atom
              ‧Example: acetic acid, hydrochloric acid

               Ionic-Base
              ‧Has a pH >7
              ‧Corrosive
              ‧Taste bitter
              ‧Always have a hydroxide atom
              ‧Example: ammonia, sodium hydroxide

              Ionic-Salt
              ‧The mixture of an acid and a base (neutralization)
              ‧Always have a salt product + H2O
              ‧Example: HCl + NaOH → NaCl + H2O

              Covalent-Organic compound

              
                ↑  The structure formula of Melamine
              ‧A compound with a carbon atom
              ‧Example: Aspartic acid, Hexafluoropropylene

The diagram of Matter and it's sub-categories:

Unit Conversions

For converting SI units, make sure to convert to the base units FIRST then you can start converting to the designated unit.

Unit Conversion Involving ONE Unit

E.g. Convert 8.6ns into ms

First, map out how you are planning to convert it: ns→s→ms

8.6ns   ×        1s               ×       10³ms    = 8.6× 10^-6ms
                   10⁹ns                        1s

Unit Conversion Involving TWO Units

E.g. Convert 90km/h to m/s

You can simply convert the top then the bottom or vice versa.
To convert the top: km→m
To convert the bottom: h →min →s

 90km     ×    10³m       ×     1h         ×     1min     =    9×10⁴m    =  25m/s
    h                1km             60min             60s              3600s             

NOTE: Make sure to write the final answer in scientific notation when coming across very SMALL or very LARGE numbers. You don't want to write 0.0000086 when you can simply just write 8.6 × 10^-6 right?

Measurements

Quantities and Measurements

• measurements are a multiple of some basic unit
• All measurements in Science come in 2 parts! It must have the number and the unit
• Both the number and the unit create a combination called a quantity
• SI(Système international d'unités) — the International System of Units — a french system using powers of 10

BASIC UNITS

Measurement             Unit              Abbreviation

length                        metre              m

time                          second             s

mass                         kilogram          kg

amount of subst.*      mole*             mol

luminous intensity       candela           cd

temperature               kelvin              K

eletric current             Ampere          A

SI PREFIXES

Lab Safety and WHMIS

Safety in the Classroom
In the below picture, you can see many of the common tools used for safety and accident handling procedures. Sinks are located throughout the classroom, and there is soap on the east counter.

Several rules are enforced for the safety of everyone during experiments, some are listed below:

• No Running
  
• No Open-toed Shoes
  
• No Eating or Drinking
  
• No Messing Around in General
  
• Do Nothing Involving Reactions Without Permission
  

Other ways to stay safe in the Chemistry classroom is knowing basic procedures. For example, if you're on fire, stop, drop, and roll! Common sense is also required to minimize bodily damage. If you're burning from acid on your skin, wash it off first, then tell the teacher.


W.H.M.I.S.

An acronym for "Workplace Hazardous Materials Information System". It is a system to help workers recognize safety and health hazards. Below is a chart identifying the hazards, along with their symbols.

  

Similarly, there are International Safety Symbols representing Poison, Flammable, Explosive, and Corrosive hazards, all having 3 degrees (Danger, Warning, and Caution).

Conclusion
The Chemistry classroom can quickly become a dangerous place to be, but this can be avoided given that everyone does their part to ensure their own and others' safety. Use your common sense and follow proper procedure. If everyone does this, it will be very unlikely someone loses an eye, a finger, a toe, or some other arbitrary body part.