Substance
a type of matter with a fixed composition
Element
when all the atoms in a substance have the same identity
compound
when two or more substances combine
heterogeneous mixture
a mixture in which different materials can be distinguished easily
homogeneous mixture
contains two or more gaseous, liquid,, or solid substances blended evenly throughout
solution
a homogeneous mixture of particles so small they cannot be seen with a microscope
colloid
a type of mixture with particles that are larger than those in solutions but not heavy enough to settle out
Tyndall effect
the scattering of light by colloidal particles
suspension
a heterogeneous mixture containing a liquid in which visible particles settle
physical property
measurable or observable characteristics of matter that can be identified without altering the substance’s chemical identity
physical change
a alteration to the form, state, or appearance of matter without changing its chemical composition or creating a new substance
distillation
a widely used separation technique that purifies liquid mixtures or separates components based on differences in their boiling points
chemical property
a substance’s ability to undergo a specific chemical change or reaction, altering its identity
chemical change
occurs when one or more substances are transformed into new substances with different compositions and properties
law of conservation of mass
any closed system, matter is neither created nor destroyed by chemical reactions or physical transformations
kinetic theory
explains the physical behavior of matter—especially gases—by proposing it consists of tiny particles (atoms or molecules) in constant, random motion
melting point
the specific temperature at which a solid substance transitions into a liquid at standard atmospheric pressure
heat of fusion
the amount of energy (heat) required to change a substance from its solid state to its liquid state at a constant temperature and pressure, specifically at its melting point
boiling point
the temperature at which a liquid changes into a gas, occurring when its vapor pressure equals the surrounding atmospheric pressure
heat of vaporization
the energy required to convert one mole or unit mass of a substance from liquid to gas at constant pressure and temperature
diffusion
the spontaneous, passive movement of particles (atoms, ions, or molecules) from a region of higher concentration to a region of lower concentration, driven by kinetic energy
plasma
a state of matter and the liquid component of blood
thermal expansion
the tendency of matter to change its shape, area, and volume in response to a change in temperature
buoyancy
the upward force exerted by a fluid (liquid or gas) that opposes the weight of an immersed object
