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

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