Question 1

What is an atomic mass unit?

Accepted Answer

An AMU (or Dalton) is 1.66 × 10⁻²⁷ kg. Defined as 1/12 the mass of carbon-12. Used for atomic and molecular masses.

Question 2

How heavy is a proton in kg?

Accepted Answer

A proton is 1.673 × 10⁻²⁷ kg or about 1.007 AMU. Neutrons are slightly heavier at 1.675 × 10⁻²⁷ kg.

Question 3

Is there a difference between mass and weight?

Accepted Answer

Yes! Mass (kg) is amount of matter, constant everywhere. Weight (newtons or pounds-force) is gravitational force on mass, varies by location.

Question 4

Why do jewelry and precious metals use different units?

Accepted Answer

Troy system (troy ounces, pennyweights) has been used for precious metals since the Middle Ages. 1 troy oz = 31.1g vs 1 regular oz = 28.35g.

Atomic Mass Units to Kilograms

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