Properties of Materials And Chemical Reactions

S Investigate the characteristic properties of metals, non-metals, and metalloids and classify elements according to these properties. S Differentiate between physical and chemical changes. Vocabulary & People State/PhaseMelting PointBoiling Point LustreMalleabilityDuctility SolubilityConductivityCombustion CorrosionOxidationHydration MetalloidsPrecipitate

Physical properties Used to describe and classify matter Traits that can be observed or measured without changing the composition of matter State/phase – solid, liquid or gas (normally) Hardness – how easy it is to scratch or dent Viscosity – how easy it flows Melting point – unique temperature needed to change from solid into liquid Boiling point – unique temperature needed to change from liquid into gas

Lustre – shiny or dull Malleability – how easy to bend or flatten (opposite – brittle) Ductility – how easy to pull into a wire Solubility – does it dissolve in water Conductivity – does it transfer heat/electricity Other examples of Physical Properties:

Chemical properties Describes how a substance will react chemically Cannot be observed without changing the original material Combustion – does it burn or ignite Corrosion – does it react with acids Oxidation – does it react with air Hydration – does it react with water Heating – does it react to heat Don’t confuse “melting” with reacting with heat – one is a phase change, the other is changing into a new compound

Metals Most common form of matter – 75% of elements Metals demonstrate similar (but NOT identical) physical and chemical properties Non-metals 15% of elements Non-metals demonstrate properties that are the opposite of metals

Metalloids: Elements on the staircase – 6% of elements Exhibit properties between metal and non-metals.

PropertyMetalNonmetalMetalloid Lustre Malleable Ductile State (Rm Tp) Conduct heat Conduct electricity (*) – there are exceptions to these properties shiny solid* dullshiny* solid / gas*solid semi * * *

Physical change Involves a change in shape or a change in state of a substance No evidence of a new material forming H H O H H O H H O Anything that changes what it “looks like” NOT “what it is”

Chemical change A new substance with new properties is formed – a chemical reaction has happened! Evidence of a chemical reaction (and chemical change) : 1.A change in colour 2.A change in smell 3. Fizzing or bubbling (new gas being made)

Testing for Gases Oxygen flame re-ignites or glows brighter Hydrogen gas explodes with a “pop”

4. A new solid forms from a mixture of liquids or the mixture goes cloudy This new solid is called a precipitate 5.A change in energy “Energy” could be light, heat, sound – think of the most obvious change in energy reaction – an EXPLOSION!

Chemical change Chemical properties Chemical Reaction Physical change Physical properties NO Reaction Test the material State or shape Δ colour Δ smell Δ energy Gas bubbles Precipitate New substance with new properties Same substance with same properties

CAN YOU ANSWER THESE QUESTIONS? S What properties classify elements as metals, nonmetals or metalloids? S How do you identify physical or chemical change and if a chemical reaction has taken place? Vocabulary & People State/PhaseMelting PointBoiling Point LustreMalleabilityDuctility SolubilityConductivityCombustion CorrosionOxidationHydration MetalloidsPrecipitate