02/12/25 QUIZ ignore for exam

Chemistry

The science that deals with the composition, structure, properties, and transformation of substances.

Isotope

Atoms of the same element that have the same number of protons but different numbers of neutrons. This difference in neutron count gives isotopes different atomic masses.

Radioisotope

An isotope with an unstable nucleus that decays over time, emitting radiation.

Particle Theory of Matter

• Matter is made of particles

• Particles are in motion

• Particles attract each other

• Particles have spaces between them

• Particles move faster as temperature increases

Ions

Atoms that have gained or lost electrons.

Molecules

Two or more atoms bonded together, forming a distinct entity with specific chemical properties.

Difference Between Atomic Models

• Dalton's Solid Sphere Model: Atoms are indivisible solid spheres.

• Thomson's Plum Pudding Model: Atoms consist of a positively charged 'pudding' with negatively charged 'plums' (electrons) embedded in it.

• Rutherford's Nuclear Model: Atoms have a small, dense, positively charged nucleus, with electrons orbiting around it.

• Bohr's Planetary Model: Electrons orbit the nucleus in fixed energy levels or shells.

• Quantum Mechanical Model: Electrons exist in probability clouds.

atomic mass

a weighted average between all isotopes of an element. mass = protons + neutrons