Chem Reflection

This year in chemistry I have really pushed my limits and gone out of my way to do the best I can, I may not be the best listener in the class but I do my best to get all my work done. I don't mess around when it comes to labs, I just do my best and take my time. this year I have learned about how to read the Table of Elements.


Helium   Scientific name
2             Atomic number
He          Symbol
4.003     Atomic Mass


Skills Lab#1
I also enjoyed the lab where we watched Aluminum foil dissolve into a liquid. We had to watch closely with color and the phases it went through,


Precision and Accuracy
precision- a measurement of how closely individual measurements agree with the correct value
accuracy- refers to how closely individual measurements (#'s) agree with the correct or true value.

 

Equations

 D= M/V or Density= Mass/ Volume
M=D(V) or Mass=Density(Volume)
V=(D)M or (Density)Mass


(prefixes)  If you're going down your decimal is moving to the right
SI              If you're going up your decimal is moving to the left
K
   H
     DK
         BASE                  EX: (20cm = .20m) (.032L= 32mL)
                D
                   C
                      M


Percent Error
What you got - Actual answer  X 100
            Actual answer

 

ZEROS
Leading - never (024556)


Trapped- always (66043)


At the end of a # - 

• Number contains a decimal - always
•   Number does not have a decimal -never

LAW OF MULTIPLE PROPORTIONS

• some elements can be more than  one compound when they react together
• Radioactivity - spontaneous emission of radiation from an atom led to the discovery of  (OX B Y)
• discovery of  electrons 1897

# Of Protons = # Of Electrons