matter, change and energy. review physical change a change that does not change the chemical...
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Matter, Change and Energy
Review
Physical Change
• A change that DOES NOT change the chemical compostion of a substance.
• Examples: melting (and all phase changes), tearing or breaking.
States of Matter• Solid – slower moving particles, strong
attractions, definite volume and shape.
• Liquid – particles move faster than solids, moderate intermolecular attractions, definite volume, no definite shape.
• Gas – rapidly moving particles, almost no intermolecular attractions, no definite volume, no definite shape.
Changes of States of Matter
Enthalpy- total energy of a system (often mostly in the form of heat).
Remember: A change of state is a physical change.
Solid, liquid, or gas?
Solid Liquid Gas
Chemical Changes• Are also known as chemical reactions.• Involve energy.• Make a new substance by rearranging atoms.• Are not easily reversed.• Are expressed in a chemical equation:
Signs of Chemical Change• Uses or release heat or
light or other forms of energy
• Changes color• Effuses gas (bubbles)• Forms a precipitant (a not
soluble solid)• Odor changes
Classification of Matter
General
Specific Order ----------------------------------------------------Disorder
Matter
Homogeneous Heterogeneous
PureSubstance
Homogeneous Mixture
Heterogeneous Mixture
Elem
ent
Com
poun
d
Solution Mixture
Symbol
Elements• One kind of matter (one kind of atom).
Compounds• Two or more different elements chemically
combined in a fixed ratio.• Elements have different properties together,
than separate.
Compounds: The Laws of Definite and Multiple Proportions
• Law of Definite Proportions: The ratios of elements in compounds do not change.
• Law of Multiple Proportions: If you change the ratio of elements, it is no longer the same compound.
• Example: H2O is water
H2O2 is hydrogen peroxide
They are very different!
Allotropes• Allotrope: Compounds made of a single
element.
Allotropes:
Not Allotropes:
Carbon Allotropes:
Heterogeneous: Simple Mixtures• Any two things together with the parts visible.• Can be separated easily.
HomogeneousHeterogeneous
Separating Mixtures
• Filtering• Decanting• Boiling or Distilling• Magnets
Homogeneous Mixtures: Solutions• When one substance dissolves (disappears)
in another because the atoms or ions separate.
• Are transparent, but may be clear or colored.
• Two parts: Solute (disappears) and Solvent.
Heterogeneous mixtures: Suspensions
• Appears homogeneous, but eventually settles or separates.
• Are cloudy
Hetero- or Homogeneous mixture? Colloids
• A permanent suspension because the particles are so tiny.
• Are cloudy• Often have a Tyndall Effect.
Introduction to the Periodic Table
The End