1.4: classification of matter

matter

• matter: anything that has mass and takes up space (has volume)

• states of matter (for most entry-level and honors chemistry courses)

  • solid (eg. ice)

  • liquid (eg. water)

  • gas (eg. water vapor)

• atoms are the building blocks of matter

• each element is made up of a unique type of atom

• a compound is made up of at least two different elements

• spheres of different colors are used to represent atoms of different elements

• attached spheres represent atoms that are connected (bonded) to each other

classifications of substances

• pure substance: a form of matter with only one kind of atom or molecule

• element: a pure stubsance with one type of atom

• compound: a pure substance with two or more types of atoms bonded together (molecules)

• mixture: a form of matter with more than one kind of atom or molecule

• homogeneous mixture: a mixture with a uniform composition

• heterogenous mixture: a mixture with a variable composition

• element: a pure substance that…

  • cannot be broken down into other substances by chemical means (by undergoing a chemical reaction)

  • is made from a unique type of atom

• atom: the smallest unit of an element that maintains all of the physical and chemical properties of the element

• diatomic element: an element which can form a molecule with another one of its atoms bonded together (they are more stable when they are paired up)

  • seven diatomic elements: H, N, O, F, Cl, Br, I

• compound: a pure substance that is composed of a combination of at least two different elements that…

  • are bonded together

  • can be broken down into the individual elements by chemical means (by undergoing a chemical reaction)

• molecules are the smallest units of a compound that maintain all of the physical and chemical properties of the compound

• compounds have a definite composition

• pure substances are forms of matter which have…

  • distinct properties

  • a composition that does not vary from sample to sample

• two types—elements cannot be physically broken down into simpler substances, and compounds can be physically broken down into simpler substances

• mixture: a combination of two or more elements and/or compounds that are not chemically bonded together

  • can be physically separated