Module 4 - Measurement Flashcards
week 4 (24 cards)
What are the three basic parts of a quantity?
Magnitude, unit, and uncertainty.
How are measurements expressed?
Using magnitudes and units.
What does a magnitude imply?
It contains implicit information about uncertainty.
What are the four main SI base units?
Meter (m), kilogram (kg), second (s), and kelvin (K).
What are derived SI units?
Units formed by combining base units.
How is scientific notation structured?
As a significand and an exponent (order of magnitude).
What are prefixes used for in scientific notation?
To express orders of magnitude.
What are exact numbers?
Defined values with infinite significant figures.
What are uncertain numbers?
The result of measurements and have a degree of uncertainty.
What indicates the number of significant figures in a quantity?
The number of digits in the significand.
Are all non-zero digits significant?
Yes.
Are zeros in decimal notation significant?
They may be, depending on their placement.
What is the rounding rule for digits greater than 5?
Round up.
What is the rounding rule for digits less than 5?
Round down.
What is the rounding rule for exactly 5?
Round to the nearest even digit.
What is accuracy?
Closeness of a measurement to an accepted standard.
What is precision?
How closely multiple measurements agree with one another.
What is the atomic mass unit (amu) based on?
The mass of a hydrogen atom (1.0 amu).
What is an amu?
A relative mass unit used to compare atomic masses.
Why was hydrogen chosen for the amu?
It is the lightest element.
What is a mole?
The number of hydrogen atoms in 1.0 g of hydrogen, 6.02 × 10^23 atoms.
What is molar mass?
The mass of one mole of a substance, in g/mol.
How are atomic masses in the Periodic Table related to molar mass?
They correspond directly in g/mol.
How do you calculate the number of moles in a sample?
Divide the mass by the molar mass.