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Chem Ch. 2
Measurements & Units
Term | Definition |
---|---|
Scientific Notation | |
Measurements | quantitative observation number & unit involved |
Exact quantities | whole number quantity |
Inexact measurements | last digit is estimated |
Accuracy | how close measurements are to a true (known) value |
Precision | how close inexact measurements are to each other |
Significant Figures | precision of a measurement |
Sig figs - exact measurement | infinite sig figs |
Sig figs - non-zero digit | always significant |
Sig figs - leading zero (0 that's LEFT to first non-zero digit) | never significant |
Sig figs - captive zero (0 between non-zero digits) | always significant |
Sig figs - trailing zero (0 to RIGHT of last non-zero digit) AFTER DECIMAL | always significant |
Sig figs - trailing zero (0 to RIGHT of last non-zero digit) BEFORE DECIMAL | use scientific notation to figure it out |
Prefixes - kilo (k) | 1000 base unit |
Prefixes - Mega (M) | 10^6 base unit |
Prefixes - deci (d) | 10^-1 base unit |
Prefixes - centi (c) | 10^-2 base unit |
Prefixes - mili (m) | 10^-3 base unit |
Prefixes - micro () | 10^-6 base unit |
Prefixes - nano (n) | 10^-9 base unit |
Sig figs - Addition/Subtraction | least number of decimal places |
Sig figs - Multiplication/Division | least number of sig figs |
Conversion factors | units multiplied/divided to be canceled out |
Density | D = M/V |