The physical sciences study the makeup, interactions, and behaviors of matter. The main disciplines are physics and chemistry.
The properties of a substance are observable characteristics that can be measured. Some properties or combinations of properties are specific to a given substance and can be used to identify it. Other properties, such as temperature, are a result of external actions on a substance.
Important Terms and Ideas: physical property, chemical property, density
The study of moving objects provides an introduction to concepts that are encountered in many other areas of physics.
Laws of motion.
Newton formulated three laws of motion that form the basis of understanding how forces affect objects and cause them to move or change their motion. They can be summarized as follows:
Objects persist in their state of rest or constant motion unless and until acted on by an external force.
Force = mass x acceleration.
For every action there is an equal and opposite reaction.
Newton also established a law of gravitation that still forms the basis of spacecraft navigation today. He established that the force of gravity is proportional to the mass of the objects and inversely proportional to the square of their distance.
Important Terms and Ideas: momentum, kinetic energy, potential energy, velocity, acceleration, force, Inverse square law, conservation of momentum, conservation of energy, mass vs weight, Newtons, Joules (units of force and mass)
The other areas of study in physics draw heavily on the concepts introduced in the study of mechanical energy, especially unites of measurement, forces, and laws of conservation.
Light and Sound
Experiments have shown that light exhibits the characteristics of particles and waves. However, the wave properties of light are most important in understanding light. The speed of light is a fundamental physical constant represented by c. Wavelength x frequency = velocity. Sound is also a wave phenomenon.
Important Terms and Ideas: wavelength; frequency; velocity; diffraction; refraction; double slit experiments; radio, microwave, infrared, visible, ultraviolet, xray, gamma ray; Doppler effect
Heat is the motion of energy from one body to another. While energy is moving, it is experienced as heat. The study of the transfer of energy as heat is called thermodynamics.
Important Terms and Ideas: temperature versus heat; measurement of heat, calories; specific heat; thermal expansion; conduction, convection, radiation; three laws of Thermodynamics; adiabatic processes; entropy
Electricity is the result of an accumulation of charged particles. Static electricity, or electrostatics, is the study of charged particles at rest. Charged particles in motion form electric currents.
Important Terms and Ideas: charges; conservation of charge; coulomb’s law; conductors, insulators; current, amperes; voltage; resistance, ohms; Ohm’s law; AC, DC electricity; power, watts; circuits, series, parallel
Magnetic forces are related to electricity. Electric currents generate a magnetic field that can move a compass needle. Magnets can exert force on current-carrying wires, and the motion of wired through a magnetic field will induce an electric current in the wire.
Important Terms and Ideas: poles; attraction and repulsion; magnetic fields; magnetic field of Earth; magnets and electric current, motors, transformers; electromagnetic waves
Matter is composed of simple particles called atoms. The study of the particle nature of matter is important in understanding how matter changes with temperature and which substances will react with each other.
Atoms are the smallest particle of a pure substance. Atoms of different substances combine to form molecules. The behavior of substances—such as change of state from solid to liquid to gas—is understood as the motion of these particles at extremely small size scales.
Important Terms and Ideas: elements, compounds; phases of matter (solid, liquid, gas); evaporation, condensation, freezing, melting, latent heat; buoyancy; air pressure; gas laws
Atoms have a nucleus consisting of uncharged neutrons and positively charged protons. The nucleus is surrounded by electrons. Neutrons and proton are thousands of times more massive than electrons, yet the nucleus occupies a tiny fraction of the space of an atom.
Important Terms and Ideas: electron, proton, neutron; Rutherford gold foil experiment; atomic weight; atomic number; isotopes; periodic table of the elements
Atoms form bonds and enter into chemical reactions based primarily on their electron configurations. Understanding of chemical reactions will come in large part from learning these configurations and how they change during a reaction.
Chemical bonding is driven primarily by the tendency of atoms to gain stable outer electron shells, usually with eight electrons. This tendency will determine whether a given atom will react with another and how many of each atom will be in the resulting molecule.
Important Terms and Ideas: stable electron shells; ionic bonds, ions; covalent bonds; valence electrons, oxidation numbers; writing formulae of compounds and naming them; solutions and solubility; radioactivity
The important principle in chemical reactions is the conservation of matter. All chemical reactions must be balanced, showing the same number of each kind of atom entering and leaving the reaction. The mole, or gram molecular weight, is the unit used when calculating quantities in reactions, known as stoichiometry.
Important Terms and Ideas: balanced chemical reaction; mole; stoichiometric calculations; exothermic, endothermic reactions; activation energy; chemical equilibrium; catalysts
Acids and Bases
Acids and bases can be defined by the ions they produce in solution. Acids produce H+ ions and bases produce OH- ions. However, they can also be defined by whether they donate protons (acids) or accept protons (bases). Both definitions are useful in understanding different aspects of acid-base chemistry.
Important Terms and Ideas: Arrhenius theory; Bronsted–Lowry theory; strength of acids and bases; conjugate acids and bases; pH scale; Lewis theory; titration; oxidation and reduction
Gas Laws and Ideal Gases
The behavior of gasses follows from the kinetic theory of matter. This theory states that matter is made up of particles—atoms and molecules—that are in constant motion. There is a large amount of space (compared to the size of the particle) in between the particles.
Important Terms and Ideas: volume, pressure, temperature, how these interplay; Boyle’s law; Charles’ law; general gas equation; ideal gas