thermo/nuclear chemistry

Thermochemistry

Study of heat and energy changes during reactions and physical changes.

Energy

Ability to do work or produce heat.

Kinetic Energy

Energy of motion.

Potential Energy

Stored energy.

Chemical Energy

Energy stored in chemical bonds.

Temperature

Average kinetic energy of particles.

Heat

Energy transferred from warmer objects to cooler objects.

Thermal Energy

Total energy of all particles in a substance.

Specific Heat

Amount of heat needed to raise 1 gram of a substance by 1°C.

Entropy

Measure of disorder/randomness.

Enthalpy

Total heat content of a system.

Conductors

Materials that transfer heat easily.

Insulators

Materials that resist heat transfer.

Triple Point

Point where solid, liquid, and gas all exist together.

Critical Point

Point where liquid and gas become indistinguishable.

Activation Energy

Minimum energy needed to start a reaction.

ΔH (Change in Enthalpy)

Heat lost or gained during a reaction.

Law of Conservation of Energy

Energy cannot be created or destroyed, only transferred.

Calorimeter

Device used to measure heat changes.

0th Law

If two objects are the same temperature as a third object, they are the same temperature as each other.

1st Law

Energy cannot be created or destroyed.

2nd Law

Entropy naturally increases.

3rd Law

At 0 Kelvin, a perfect crystal has zero entropy.

Conduction

Heat transfer through direct contact.

Convection

Heat transfer through liquids or gases.

Radiation

Heat transfer through waves.

Melting

Solid → Liquid

Freezing

Liquid → Solid

Vaporization

Liquid → Gas

Condensation

Gas → Liquid

Sublimation

Solid → Gas

Deposition

Gas → Solid

Endothermic Reactions

(Absorb heat, Surroundings feel cold, Example: cold packs)

Exothermic Reactions

(Release heat, Surroundings feel warm, Example: fire)

Nuclear Chemistry

Study of changes in the nucleus of atoms.

Atomic Number

Number of protons.

Mass Number

Protons + neutrons.

Isotopes

Atoms of the same element with different neutrons.

Radioactive Decay

Process where unstable nuclei release radiation.

Stable Nucleus

A nucleus that does not decay easily.

Unstable Nucleus

A nucleus that decays and releases radiation.

Critical Mass

Minimum amount needed for a nuclear chain reaction.

Fission

Large nucleus splits into smaller nuclei and releases energy.

Fusion

Small nuclei combine into a larger nucleus and release energy. Powers the Sun.

Chemical Reactions

(Involve electrons, Small energy changes, Elements stay the same)

Nuclear Reactions

(Involve the nucleus, Can change one element into another, Release huge amounts of energy)