Thermochemistry and Nuclear Chemistry Review

Flashcards covering thermochemistry and nuclear chemistry concepts.

Thermochemistry

The study of energy changes during chemical reactions and physical changes.

Energy

The ability to do work or produce heat, measured in Joules.

Temperature

The average kinetic energy of a substance (atoms), measured in Kelvin or Celsius.

Kinetic energy

Energy of matter in motion.

Potential energy

Ability to do work due to position, composition, or configuration (stored energy).

Chemical energy

Potential energy stored in chemical bonds of a substance.

Temperature

Measures the hotness or coldness of matter.

Heat

Energy transferred between matter due to temperature differences; moves from warmer to cooler object.

Thermal energy

Total potential and kinetic energy of molecules in a substance due to arrangement and motion.

Law of Energy Conservation

In an insulated system, heat lost by one quantity of matter is gained by another.

Entropy

Measure of the molecular disorder/randomness of a system, dependent on a system's state.

Enthalpy

Total heat content of a system.

Conduction

Transfer of energy through direct contact.

Convection

Transfer of energy through liquids or gas.

Radiation

Transfer of energy through waves.

Insulators

Prevent the transfer of thermal energy.

Conductors

Allow the transfer of thermal energy.

Freezing

Liquid to solid phase change.

Melting

Solid to liquid phase change.

Vaporization

Liquid to gas phase change.

Condensation

Gas to liquid phase change.

Sublimation

Solid to gas phase change.

Deposition

Gas to solid phase change.

Atomic Number

Identity of the element / number of protons.

Mass Number

Protons + neutrons.

Protons

Positive charge / inside nucleus.

Electrons

Negative charge / outside nucleus.

Neutrons

Neutral charge / inside nucleus.

Isotopes

Same element with different numbers of neutrons.

Technetium-99

Medical imaging of tumors.

Iodine-131

Thyroid disorders identification.

Cobalt-60

Radiation therapy, cancer treatment.

Carbon-14

Archaeological reserves.

Americium-241

Smoke detectors.

Plutonium-239/Uranium-235

Bombs.

Radioactive decay

Nuclei that are not stable, tend to undergo this.

Chemical Reactions

Involves valence electrons; elements rearranged to form new compounds; obeys the Law of Conservation of Mass; releases little energy.

Nuclear Reactions

Changes occur in the nucleus; transmutation occurs; the Law of Conservation of Mass is not always obeyed (mass is changed into energy); produces lots of energy.

Alpha Decay

Loses an alpha particle; atomic number decreases by 2; mass number decreases by 4; a new element is formed.

Beta Decay

Loses an electron from the nucleus; neutron splits into a proton and an electron; a new element is formed; atomic number increases by 1; mass number is unchanged.

Gamma Radiation

A nucleus in an excited state lowers its energy by emitting photons; no change in atomic number or mass number.

Positron Emission

Positron is emitted from the nucleus; a proton in the nucleus is converted into a neutron; atomic number decreases by 1; mass number is unchanged.

Neutron Bombardment

A neutron enters a nucleus creating a radioactive isotope.

Electron Capture

A low-energy electron in the atom is absorbed by the nucleus; converts a proton to a neutron; atomic number decreases by 1; mass number unchanged.

Fission

Occurs when a neutron hits a large, unstable nucleus and causes it to break into smaller nuclei.

Critical Mass

Amount of substance needed for a chain reaction to occur.

Fusion

The process by which small nuclei fuse together to form a heavier nucleus.

Half Life

Amount of time required for half of the nuclei of a radioactive element to undergo radioactive decay.