Safety, Matter, and Measurement
Lab Safety
Dress appropriately
Follow directions and act appropriately
Know where emergency equipment is
MSDS
Material Safety Data Sheets- contain safety information about chemicals
Converting metric units
Kilo Hecto Deca Base Deci Centi Milli
1000 100 10 1 1/10 1/100 1/1000
Significant Figures
NOT Significant Digits
“Placeholders”- Zeros before the decimal point and after the number - Zeros after the decimal point and before the number
Significant digits
All non-zero digits
“sandwiched” zeros
Zeros after decimal point and after number
Addition and Subtraction- round to the least # decimal places
Multiplication and Division- round to the least # significant digits
Accuracy and Precision
Precision- The specificity of the measurement (ie: 3.0000001 g)
Accuracy- The actuality if the measurement (ie: TRUE weight it 5.6 g)
Atoms, Isotopes, and Atom Theories
Using atomic number and mass # to count protons, electrons, and neutrons
Atomic number= # protons= # electrons
Mass number= protons+ neutrons (so: mass # - # protons= #neutrons)
Isotopes- variation of neutrons in an element(top left corner of atomic symbol)
H, H, H
Counting protons, electrons, and neutrons in IONS
Ion- # of electrons (top right # on atomic symbol) H, H, H
Cation(metal)- lost/less electrons(+)
Anion (non-metal)- gained/more electrons(-)
Calculating Average Atomic Mass from isotope masses and percentages
Average Atomic Mass=
(amu x .%)+ (amu x .%)= aam
Atomic Theories
Dalton
Thomson
Rutherford
Gold-Foil Experiment
Shot alpha particles at gold foil; the particles either went straight through, or bounced back at large angles
Atoms, Molecules, Formula Units, Mole, Mole Conversions, Percent Composition
Identifying atoms, molecules, and formula units
Atoms
Molecules
Formula units
Understanding one mole