🔬Unit 2: Matter + Phase Changes (Chemistry)

matter

anything that has mass and takes up space

pure substance

matter that has a fixed or definite composition

mixture

combination of two or more pure substances (substances retain their individual properties) (e.g. milk and salt)

element

pure substance that cannot be broken down and it’s composed of one kind of atom (e.g. iron and magnesium)

compound

pure substance made of two or more elements (e.g. salt and water)

homogeneous

looks the same everywhere, solid, liquid, or a gas (e.g. honey, steel, air)

heterogeneous

varied composition, wolid/solid, solid/liquid, solid/gas, (e.g. salad dressing, cookie dough)

solid

have a definite shape and volume, vibration is slow, arranged rigidly, close together

liquid

definite volume, but not shape, slow vibration, farther apart

gas

no definite shape, no definite volume, fast vibration, very far apart

physical property

characteristics observed and measured without affecting identity (e.g. shape, color, melting point)

chemical property

ability of a substance to change into a new substance

physical change

state, size, or appearance change

chemical change

substance is converted into one or more new substances

temperature

the speed at which molecules move

heat

the energy associated with the motion of particles in a substance

phase change

happens when subjects shift from one phase to another (e.g. melting, boiling, sublimation)

heating curve

a diagram that illustrates the temperature changes and changes of state of a substance as it is heated

cooling curve

a diagram that illustrates temperature changes and changes of a substance when heat is removed

melting

the process of shifting from a solid to a liquid (breaking intramolecular bonds)

freezing

the process of going from a liquid to a solid

boiling

the formation of bubbles of gas throughout a liquid

condensation

the process where a vapor becomes a liquid (intramolecular bonds are forming)