Download CHAPTER 2: MATTER

 Does
matter matter?
 Of course it does –
 It’s all around, in and out,
 In fact, it’s what we’re all about!
 Anything
with mass and volume
 Composed of atoms
 All one type of atom = element
 More than one kind of atom bonded in a
specific ratio = compound
 Elements and compounds are pure
substances (in chemistry usually referred
to as just substances)
 Solid
– lowest energy , atoms/molecules
vibrate, but have a fixed position – definite
volume and definite shape
 Liquid – moderate energy – atoms/molecules
roll and tumble about each other, flow
definite volume and variable shape
 Gas – high energy, atoms/molecules are
moving rapidly and colliding with each other,
variable shape and volume
 Plasma – highest energy, ionized particles,
sun, stars, lightning
 Melting
– solid to liquid
 Freezing – liquid to solid
 Evaporation – liquid to gas at room temp.
 Vaporization – liquid to gas with heat added
 Condensation – gas to liquid
 Sublimation – solid to gas
 Deposition – gas to solid
 Phase
changes are physical changes
 Unique
characteristics of a substance that
can be observed without changing the
substance.
 Such as:odor, color, volume, state (phase),
density, melting point and boiling point
 Extensive
physical properties depend on
the quantity of the sample.
 Such as: mass, length, volume
 Intensive physical properties do not vary
with the quantity of the sample.
 Such as: density, color, boiling point
 Properties
of a substance that can only be
observed by actually changing the
substance into something else. New
substances are formed during a chemical
reaction.
 Such as: flammability (burning), rusting or
tarnishing
 Changes
that do not affect the composition
of the substance.
 A change in one or more physical
properties.
 Such as: size (tearing a sheet of paper into
small pieces), phase change (solid to liquid)
 Changes
that involve a change in the
fundamental components of a substance.
One or more substances change into one or
more new substances through a chemical
reaction.
 Such as: hydrogen combining with oxygen to
form water
 Reactant + reactant  Product
 Reactant  product + product
 What might indicate a chemical change has
occurred?
 Dramatic
change of color
 Production of a gas
 Production of a new and different odor
 Production of a precipitate (solid)
 Change in energy (change in temperature,
sound, light)
 Pure
substances – elements and compounds
– definite composition
 Mixtures – things with variable composition
such as salt water or wood. May be
homogeneous or heterogeneous.
 Homogeneous mixture– same throughout –
aka solution – ex. Kool-Aid, alloys, air
 Heterogeneous mixture – regions with
different properties –ex. Italian salad
dressing, muddy water
 Alloy – homogeneous mixture (solution) of
metallic elements –ex. Sterling silver
 Mixtures
can be separated by physical
means such as:
 Filtration – particle size
 Distillation/evaporation – boiling points
 Extraction – solubility
 (Re)Crystallization –
evaporation/vaporization
 Decanting – pouring to leave sediment
 Chromatography – molecular weight
 Centrifuging – particle size, weight, state