ChemistryChapter 16: Empirical Data Collection and Analysis
SI Base and Derived Units
SI has seven base units.
Learning objectives
- State the main idea of si base and derived units in clear words.
- Explain why si base and derived units is useful in chemistry.
- Apply the correct method, observation, equation, or comparison.
- Avoid the common mistakes and write a complete exam answer.
What this grid covers
SI has seven base units. They are independent: none is made from the others. Derived units are made by combining base units. Lab work often prefers g and cm3, but the SI volume unit is m3.
Important terms
- seven base units
- SI has seven base units.
- Derived units
- SI has seven base units.
- combining
- SI has seven base units.
WHAT — Core idea
SI has seven base units. They are independent: none is made from the others. Derived units are made by combining base units. Lab work often prefers g and cm3, but the SI volume unit is m3.
WHY — Why it matters
Mass is kg, not gram. Temperature is K. Volume in SI is m3, but a measuring cylinder is marked in cm3. 1 dm3 = 1000 cm3, and 1 L = 1000 mL = 1 dm3. Also 1 mL = 1 cm3.
HOW — Method, evidence, or comparison
Mass → kilogram → kg; Length → metre → m; Time → second → s; Temperature → kelvin → K; Amount of substance → mole → mol; Electric current → ampere → A; Luminous intensity → candela → cd
HOW — Answer in an exam
Mass is kg, not gram. Temperature is K. Volume in SI is m3, but a measuring cylinder is marked in cm3. 1 dm3 = 1000 cm3, and 1 L = 1000 mL = 1 dm3. Also 1 mL = 1 cm3.
The seven SI base quantities:
| Quantity | Unit name | Symbol |
|---|---|---|
| 1. Mass | kilogram | kg |
| 2. Length | metre | m |
| 3. Time | second | s |
| 4. Temperature | kelvin | K |
| 5. Amount of substance | mole | mol |
| 6. Electric current | ampere | A |
| 7. Luminous intensity | candela | cd |
In simple words
Mass is kg, not gram. Temperature is K. Volume in SI is m3, but a measuring cylinder is marked in cm3. 1 dm3 = 1000 cm3, and 1 L = 1000 mL = 1 dm3. Also 1 mL = 1 cm3.
Key points
- seven base units
- Derived units
- combining
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.SI Base and Derived Units
Sticky Notes · Quick Revision
WHAT
- SI has seven base units.
Key Points
- seven base units
- Derived units
- combining
HOW
- Mass is kg, not gram.
- Temperature is K.
Example
- Mass — kilogram — kg
- Length — metre — m
- Time — second — s
Common Mistake
- The SI base unit of mass is kilogram, not gram.
Exam Tip
- Mass is kg, not gram.
- Temperature is K.
60-second revision
- SI has seven base units.
- They are independent: none is made from the others.
- Mass is kg, not gram.
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