Matter: Chemical and Physical Properties Explained

• Matter can be defined by its properties, characteristics, and behavior.
• Properties of matter can be chemical, physical, intensive, or extensive.

Chemical Properties

• Chemical properties describe a substance's ability or inability to combine with or change into another substance, relating to chemical changes (chemical reactions).
• Reactivity indicates how a substance reacts.
• Instability describes the tendency of a substance to break down into different substances.
• Toxicity indicates how poisonous or toxic a substance is.
• pH describes how acidic or basic a substance is.
• Flammability defines the ease with which a substance will burn.
• Melting point is the temperature at which a substance melts.

Physical Properties

• Physical properties are characteristics that can be measured or observed without changing the composition of the substance.
• Mass measures the amount of matter; mass is constant, while weight measures gravitational force.
• Volume measures the amount of space occupied.
• Color is described using ROYGBIV (red, orange, yellow, green, blue, indigo, violet).
• Texture describes how a substance feels.
• Hardness is the quality of being firm or solid.
• Malleability is the ability to be hammered.
• Elasticity is the ability to return to an original position after being stretched.
• Ductility is the ability to be drawn into a wire.
• Conductivity is the ability to transfer heat, electricity, or sound.
• Solubility is the capacity to be dissolved.
• Boiling point is reached when vapor pressure equals external pressure.
• Freezing point is when a liquid solidifies.
• Density is mass per volume unit.

Properties of Matter

• Intensive properties do not change with the amount of substance and can be used for identification.
• Extensive properties change constantly and cannot be used for identification.
• Matter takes up space, has mass, and is made of atoms.

Atoms and Molecules

• Atoms are the building blocks of matter and are too small to be seen; an Angstrom is a unit of length equal to one ten-millionth of a millimeter.
• A molecule consists of two or more atoms combined in a specific arrangement.

States of Matter

• Gas particles move randomly and quickly in straight lines, taking the shape of their container.
• Liquid particles move and change locations but not as freely as gas.
• Solid particles are held together with definite shapes and volumes.

Phase Changes

• Evaporation is the change from liquid to gas and is a cooling process.
• Condensation is the change from gas to liquid.
• Melting is the change from solid to liquid.
• Freezing is the change from liquid to solid.
• Sublimation is the change from solid to gas.
• Deposition is the change from gas to solid.

Atomic Structure and Models

• Atoms are electrically neutral but contain electrically charged particles.
• Protons have a positive charge.
• Electrons have a negative charge and are the lightest subatomic particle.
• Neutrons are neutral and the heaviest subatomic particle.
• Democritus and Leucippus believed that nature consists of atoms and the void; "atomos" means indivisible particle.
• Democritus believed atoms were uniform, solid, hard, incompressible, and indestructible, though Aristotle thought the world was composed of air, fire, earth, and water.
• John Dalton (1803) envisioned atoms as solid, hard spheres, and used wooden balls to model them (Solid sphere/billiard ball/bowling ball model).
• JJ Thomson (1904) discovered the electron and proposed the plum pudding model.
• Ernest Rutherford (1911) discovered the proton while performing the Alpha Particle Scattering Experiment (Nuclear model).
• Neils Bohr (1913) proposed that electrons encircle the nucleus in specific paths called orbits (Planetary/Bohr model).
• Erwin Schrodinger (1926) used mathematical equations to describe the likelihood of finding electrons in certain positions (Quantum mechanical model).
• James Chadwick discovered the neutron.

Periodic Table Organization and Properties

• Elements in the periodic table are arranged based on atomic number, electronic configuration, and recurring chemical properties.
• Atomic number equals the number of protons.
• In a neutral atom, the number of protons equals the number of electrons.
• Charge is the number of protons minus the number of electrons; positive charge involves subtraction, and negative charge involves addition.
• Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
• Mass number distinguishes an isotope of a particular element from its other isotopes.
• Mass number is the sum of protons and neutrons.
• The number of neutrons is calculated as mass number minus atomic number (number of protons).
• Mass number is the sum of the number of protons and neutrons.
• Atomic mass/atomic weight is the weighted average mass of an atom.

Periodic Table History and Trends

• Johann Wolfgang Dobereiner (1829) identified groups of 3 elements with similar properties (triads).
• John Newlands (1863) arranged the periodic table by increasing atomic masses, noting that every 8th element had similar properties (Law of Octaves).
• Dmitri Mendeleev (1869), the "Father of the Periodic Table," created the periodic table's framework and believed atomic mass was the key property for classifying elements; Mendeleev predicted properties of undiscovered elements.
• Mendeleev’s Law states that the physical and chemical properties of elements are periodic functions of their atomic masses.
• Henry Moseley (1913) determined that atomic number, not atomic mass, is the fundamental property of an element.
• The Modern Periodic Law states that the chemical and physical properties of elements are periodic functions of their atomic number.

Periodic Table Trends

• Period refers to a horizontal row (1-7) in the periodic table.
• Groups/Families refer to vertical columns (1-18) in the periodic table.
• Atomic radius is the distance from an atom's nucleus to its outermost electron orbital (decreases left to right, increases top to bottom).
• Ionic radius is the distance from the nucleus of an ion to the point where it influences its electron cloud (decreases left to right, increases top to bottom).
• Ionization energy is the energy required to remove an electron from an atom; higher ionization energy means it is harder to lose an electron (increases left to right, decreases top to bottom).
• Electron affinity is the energy released when an atom gains an electron (increases left to right, decreases top to bottom).
• Electronegativity is an atom's tendency to attract electrons towards itself; higher electronegativity means a greater chance of attracting electrons.
• Metallic property is an atom's tendency to lose electrons; more metallic means it more easily loses electrons.
• Nonmetallic property indicates how easily an atom gains an electron.
• Metallic character decreases from left to right and increases from top to bottom.
• Nonmetallic character increases from left to right and decreases from top to bottom.
• Reactivity of a metal is its ability to ionize or share electrons; more reactive metals gain or lose electrons, while less reactive metals share electrons.
• Less reactive metals cannot replace more reactive metals (no reaction).
• More reactive metals can replace less reactive metals (produce a reaction).

Explore the characteristics of matter with a focus on chemical and physical properties. Understand reactivity, instability, toxicity, pH, and flammability. Learn how mass and volume define matter without altering its chemical composition.