Mass ratio determines how far you can go
The Tsiolkovsky rocket equation (deltav = exhaust velocity * ln(mass ratio)) relates the velocity change a rocket can achieve to its initial and final masses and the exhaust velocity of its propellant. The natural logarithm of the mass ratio is the key: doubling the mass ratio (e.g., from 10:1 to 20:1) increases deltav by only 70 percent, a consequence of carrying propellant mass that must itself be accelerated.
Chemical rockets (using hydrogen/oxygen or hydrazine propellants) have exhaust velocities around 4-5 kilometers per second. To reach orbital velocity (7.8 km/s from Earth's surface), a rocket must overcome gravity, atmosphere, and achieve the target velocity. The mass ratio required is roughly 15:1, meaning 93 percent of the rocket's initial mass is propellant and 7 percent is payload (fuel tanks, engines, structure, cargo).
Why staging and ion drives matter
A single-stage rocket cannot reach orbital velocity with realistic mass ratios. Staging (dropping spent engines and tanks) resets the mass calculation. Each stage starts with a new mass ratio, allowing the final stage to achieve much higher velocity than a single stage could. The Saturn V moon rocket achieved 11 kilometers per second (escape velocity) using three stages.
Ion drives achieve much higher exhaust velocities (20-50 km/s or more) by accelerating ions electrically rather than chemically. The trade-off is low thrust; ion drives take months to change spacecraft velocity, whereas chemical rockets provide rapid acceleration. For long-duration missions with modest velocity requirements, ion drives win on fuel efficiency.