Measurement & matter · Topic 1 of 15

Scientific Notation, SI Units & Temperature Scales

Tap any line to see why it matters

Chemistry · measurement

Write numbers as a × 10ⁿ, know SI units and prefixes, and convert: °C = (°F − 32) × 5/9, K = °C + 273.

01 · The forma × 10ⁿ, with 1 ≤ a < 10

02 · °F → °C°C = (°F − 32) × 5/9

03 · °C → KK = °C + 273

0 K = absolute zero (−273 °C); kelvin is never negative

Scientific notation = a × 10ⁿ, where 1 ≤ a < 10 must know

Exponent = places the decimal moves: ≥ 10 → +, below 1 → − (0.006 = 6 × 10⁻³) must know

Multiply: multiply the coefficients, add the exponents

Divide: divide the coefficients, subtract the exponents

To a smaller unit multiply, to a larger unit divide (by the 10ⁿ gap)

°C = (°F − 32) × 5/9 · °F = (°C × 9/5) + 32 must know

K = °C + 273 · °C = K − 273 (no degree sign on K) must know

kilo = 10³ · centi = 10⁻² · milli = 10⁻³ · micro (µ) = 10⁻⁶ must know

SI base units: meter, kilogram, second, kelvin, mole (+ ampere, candela)

1 mL = 1 cm³ (1 cc) · 1 L = 1,000 mL = 1 dm³

Water freezes 0 °C/32 °F/273 K, boils 100 °C/212 °F/373 K; body 37 °C/98.6 °F

(3.0 × 10⁴) × (2.5 × 10⁻⁷) = 7.5 × 10⁻³

59 °F → (59 − 32) × 5/9 = 15 °C → 15 + 273 = 288 K

0.0063 kg × 10⁶ mg/kg = 6.3 × 10³ mg (6,300 mg)

Commonly confused

Re-normalize the coefficient: 15 × 10⁴ = 1.5 × 10⁵

Trap: the SI mass unit is the kilogram; the SI temperature unit is the kelvin

Show 3 more facts

Add or subtract only after matching the powers of 10

Same-size steps: a 10 °C change = 10 K; a 1 °C change = 1.8 °F

mega 10⁶ · hecto 10² · deka 10¹ · deci 10⁻¹ · nano 10⁻⁹

Pearl

Big numbers get positive exponents; numbers smaller than 1 get negative exponents.

Practice this topic, then test the whole section.

HESI and HESI A2 are registered trademarks of Elsevier. NurseSavvy is not affiliated with or endorsed by Elsevier.