Intro to Chemistry by DVfdoh

VIEWS: 0 PAGES: 20

									      States of Matter and
Physical and Chemical Changes




                                1
  Chemistry is the study of matter.
• What is matter?
• Matter: anything that takes
  up space (volume) and has
  a mass.




                                  2
           Properties of matter:
• Physical properties: are observable and do not
  change the chemical composition of the matter.
  Examples of physical properties: different densities,
  melting points, boiling points, freezing points, colour,
  odour (smell) and state of matter (solid, liquid or gas).


• Chemical properties: are only observable through a
  chemical reaction, and do change the chemical
  composition of the matter (new substance produced by
  destroying the original substances). Ex: burning, rusting,
  reactivity with water or acid.

                                                               3
• Chemical Properties:
  A good example of
  chemical properties is
  the way compounds
  or elements combine
  with each other during
  chemical reactions




                           4
              States of Matter
• Matter can be found in 3 states:

• 1. Solid
• 2. Liquid
• 3. Gas




                                     5
                States of Matter
• Solid: definite shape and
  volume, molecules close
  together, rigid formation,
  little molecular movement
  (vibration). Particles in a
  solid are held together by
  very strong attractive forces
  (like strong magnets next to
  one another). There is an
  extremely small change in
  the volume of solids with
  changes in temperature
  and pressure.                    6
• Liquid: indefinite shape and
  definite volume, molecules
  further apart than solids,
  more molecular movement.
  Forces of attraction are a
  little weaker and allow
  particles to flow by one
  another (think of tipping a
  box of marbles – they will
  flow).
• Temperature and pressure
  changes have a small affect
  on the volume of liquids.
                                 7
• Gas: indefinite shape and
  volume.
• Molecules are far apart (no
  attractive forces between
  the particles because of the
  distance – think of magnets
  far away from one another.
• The most molecular
  movement (particles are in
  constant motion).
• Gas volumes are greatly
  affected by temperature
  and pressure changes.

                                 8
           Kinds of Change:
    physical change: no new substance is
formed, properties such as size, shape, colour
or state may change (example: Boiling water
– have liquid water to start and water as a gas
at the end or the heating element on a stove –
black when off and red when on high and
back t black when off again). Easily reversed.
    chemical change: new substances (with
new properties) are formed from 2 or more
reacting substances. (example: rusting of iron
or burning paper) Not easily reversed.
                                             9
Examples:




            10
     Classify the following as a physical
            or chemical change:

•   A) freezing water          • E) rusting a nail
•   B) burning gas             • F) tearing a piece of
•   C) melting butter            paper
•   D) stretching an elastic   • G) rotting an apple
    band                       • H) water freezing




                                                         11
        Mixtures and Pure Substances:

• Matter can be broken down into two categories:

• 1. Pure substance: substances containing only one
  kind of matter (atoms or molecules). Examples: oxygen,
  water.

• 2. Mixtures: contains at least two kinds of matter that
  are physically mixed (blended) together (most things
  around us are mixtures). A mixture is a combination of
  pure substances. Ex: salt water, air, salt and pepper,
  dirt.
Classification of matter




                           13
                Glossary:
• Pure substance: contains one type of
  particle.
  – Elements: one kind of atom (Sulfur)
  – Compounds: contains at least two atoms of
    different elements bonded together (H2O)
• Mixture: contains two or more types of
  particles intermingling, no chemical
  bonding.
  – Homogeneous: uniform throughout only see
    one component (solution)
  – Heterogeneous: see the two components not
    uniform (salt and pepper mixed)
                                                14
• Composed of two or
  more different atoms
  (elements)
• Examples:
  water (H2O), 2 atoms
  of hydrogen, I atom of
  oxygen)
  salt (NaCl), 1 atom of
  sodium, 1 atom of
  chlorine
                           15
• An element is a
  substance made up of
  only one kind of atom.
  (Iron is made up of iron
  atoms)
• The periodic table
  arranges elements
  according to their
  properties

                             16
Heterogeneous

         • 2 or more parts
           can be seen
         • Different kinds of
           particles stay
           together.
         • Mechanical
           (physical) mixing
         • Ex: sand and
           salt, blood, milk

                            17
 Homogeneous

           • Appears to be one
             substance
           • Particles are intermingled
           • Are solutions (solute
             substance dissolved)
             (Solvent substance that is
Solution     doing the dissolving)
           • Ex: air, salt water (salt is
             the solute and water is the
             solvent)
                                      18
19
             Classification of matter




See two       See one      Contains at least   Only one kind
                           two elements (can   of atom (can
components    component    be broken down      not be broken
(parts)       (part)       into elements)      down) 20

								
To top