All substances have properties… Including people! Example: People can be identified by their … Face (shape, expressions) Voice Height Finger prints Eye color Hair color Teeth DNA

Physical Properties Physical properties are physical characteristics that identify the element based on its nature such as: Melting point: the temperature at which the solid changes to liquid State at room temperature: solid, liquid or gas

Density: the mass per volume

Luster: the ability to reflect light in a metallic shine Boiling point: the temperature at which the liquid changes to a gas Viscosity: the ease with which a substance flows. This is a descriptor of liquids. Water flows more easily and is therefore, more viscous, than honey.

Colour Clarity or Transparency: the amount of light that can pass through a substance. Opaque: when no light passes through Translucent: when some light passes through Transparent: when all light passes through

Malleability: the ability to be hammered into thin sheets Ductility: the ability to be drawn into wire Conductivity: the ability to conduct heat or electricity Solubility: the ability to dissolve in water.

Physical Properties can be classified as Quantitative or Qualitative: physical state melting point colour boiling point odour density crystal shape solubility malleability   ductility hardness brittleness texture Qualitative properties describe matter using words. They cannot be measured or expressed numerically (no numbers involved). Quantitative properties can be measured and expressed numerically (numbers are involved)

Chemical Properties Chemical properties describe how a substance reacts with another substance to form a new substance Flammability Rusting Reactivity with metals Reactivity with oxygen Reactivity with water with acids

Physical and Chemical Changes PHYSICAL CHANGES: do not produce a new substance (it’s still the same substance with same properties) involve only one substance (except dissolving) are changes in form (powder, crystal, cubes, granular) or state (solid, liquid, or gas) most are easily reversible   Examples of physical changes… Cutting Tearing Grinding Change in State Dissolving Molding (shaping)

CHEMICAL CHANGES: always produce a new substance which has different properties from the starting substance(s) involve more than one substance many are not reversible Examples of chemical changes… Burning rusting eating (saliva action on food)

How can we tell if a chemical change has occurred? Look for clues that a new substance has formed

Clues that indicate that a new substance has formed in a chemical reaction are; colour change (not a blending of the initial colours) gas (bubbles) is produced (not from boiling) a solid (precipitate) is formed when two solutions are mixed together energy is released (usually heat or light) or absorbed (substance feels colder), but not because of heating with a burner or cooling with ice etc. odour change / new odour

Physical or Chemical Change?

Physical or Chemical Change?

Physical or Chemical Change?

Physical or Chemical Change?

Physical or Chemical Change?

Physical or Chemical Change?