Chem I Exam 1

• Solid to a gas is called sublimation
• Gas to solid is called deposition
• The solid/liquid transition is called the Melting point and includes melting and freezing.
• The liquid/gas transition is called the Boiling point and includes evaporation and condensation.
• Impossible changes are things that add and take away aspects. 
• Kinetic is motion-based.
• Potential is position-based.
• By measuring temperature you measure kinetic energy.
• Low Potential Energy means it's stable.
• High Potential Energy means it is not stable.
• Chemical systems will try to minimize their potential energy.
• Low Kinetic Energy = High Potential Energy
• Low Kinetic Energy = High Potential Energy
• Changes are impossible if they violate the Law of Conservation of Mass.
• Objects tend toward charge balance (the cancellation of charges)
• Accuracy refers to the closeness of a measurement to an accepted value.
• Error is the opposite of accuracy
• Random errors fluctuate around the accepted value with no real cause
• Systematic errors are consistently one-sided and have an attributable cause.
• Precision refers to the closeness of individual measurements to one another.
• Reproducibility is high precision.
• Uncertainty is the opposite of of precision. 
• Accuracy and Precision are independent of one another.
• The term Accuracy is related to the term error.
• The term Precision is related to the term reproducibility and uncertainty.
• The Symbol for Mega is M and the exponent is 10^6
• The Symbol for kilo is k and the exponent is 10^3
• The symbol for hecto is h and the exponent is 10^2
• The symbol for deca is da and the exponent is 10^1
• When adding/subtracting sigfigs, determine how many digits are after the decimal for each measurement, and round your answer so that it has the least number of digits after the decimal.
• K = ºC + 273.15.
• When multiplying/dividing units, determine how significant figures are in each measurement and Round your answer so that it has the least number of significant figures
• For Significant Figures, If there is a decimal, Start on the left hand side of the number. Start counting at first nonzero digit.
• For Signifiant Figures if there is NO decimal, Start on the right hand side of the number. Start counting at first nonzero digit.
• The number of protons is called the atomic number. It is located at the top center of the box.
• Electrons DO NOT orbit the nucleus like planets around the Sun! Instead, they follow pseudorandom paths.
• Subatomic particles are smaller than atoms. (Protons & Neutrons)
• The mass number of an atom is defined as protons + neutrons.
• Isotopes are versions of elements that have different masses which means they have same proton count but different neutron count. Their mass number is written at the top left (e.g., 14C, 13C, 12C).
• Any substance with a net charge is called an ion.