Physical & Chemical Properties and Changes

• Physical properties are substance characteristics observed/measured without changing chemical composition.
• Examples of physical properties include color, odor, density, melting/boiling points, hardness, solubility, and electrical conductivity.
• Intensive properties, such as density and boiling point, are independent of the amount of substance.
• Extensive properties, like mass and volume, depend on the amount of substance.

Chemical Properties

• Chemical properties describe how a substance interacts to form new substances.
• Reactivity with water, flammability, acidity/basicity, oxidation states, toxicity, and corrosion are examples of chemical properties.

Physical Change

• Physical change alters appearance/state without changing chemical composition.
• Examples of physical change include melting ice, boiling water, breaking glass, dissolving sugar in water, or crushing a can.

Chemical Change

• Chemical change transforms a substance into a new one with different chemical properties.
• Indicators of chemical change include a color change, gas production (bubbling), precipitate formation, or heat/light release or absorption.
• Examples of chemical change: combustion, rusting, digestion, baking.

Kinetic Molecular Theory

• Kinetic Molecular Theory explains gas behavior based on molecule motion.
• Matter is composed of tiny particles (atoms or molecules) in constant motion.
• Temperature relates to the average kinetic energy of particles.
• Gas particles neither attract nor repel and are far apart.
• Collisions between gas particles are perfectly elastic.

Electrons

• Electrons are subatomic particles with a negative charge, orbiting the nucleus.
• Electrons have very small mass (approximately 1/1836th of a proton).
• They are located outside the nucleus in electron shells or orbitals.
• Electrons are responsible for chemical bonding and electrical conductivity.

Protons

• Protons are subatomic particles with a positive charge, found in the nucleus.
• Protons have a mass of approximately 1 atomic mass unit (amu).
• They have a positive charge (+1).
• The number of protons determines the atomic number/element.

Neutrons

• Neutrons are subatomic particles with no charge (neutral) in the nucleus.
• Neutrons have a mass of approximately 1 atomic mass unit (amu).
• Neutrons contribute to atomic mass and nuclear stability.
• The number of neutrons can vary within atoms of the same element (isotopes).

Nucleus

• The nucleus is the atom's central core, containing protons and neutrons.
• It contains most of the atom's mass.
• The nucleus is positively charged due to protons.
• Nucleus is small but dense.

Lepton

• Leptons are elementary particles that do not participate in strong interactions.
• Examples: electron (e⁻), muon (μ⁻), tau (τ⁻).
• Leptons have a half-integer spin (fermions).
• Electrons are fundamental in electricity and chemistry.

Quark

• Quarks are elementary particles that comprise protons and neutrons (baryons).
• Types of quarks: up (u), down (d), strange (s), charm (c), bottom (b), top (t).
• Up quarks have a positive charge (+2/3e).
• Down quarks have a negative charge (-1/3e).
• Protons consist of two up quarks and one down quark (uud).
• Neutrons consist of two down quarks and one up quark (udd).
• Quarks are held together by the strong nuclear force, mediated by gluons.