Chapter 5

KEY WORDS

Scientific modelA way of picturing processes that can’t be seen

Ex. particle theory

Heterogeneous

Not uniformly mixed particles

Salad, smarties, homogenized milk, metal ores smog

Homogeneous

Describes pure substances and mixtures that are uniform throughout

Ex. Solutions, alloys , elements and compounds

Solution

• Homogeneous mixture of two or more pure substances

ex. Solution = Salt water Solute = salt (the substance dissolved) Solvent= water (the substance in which the solute is dissolved)

Mechanical mixture

• Made of more than one kind of particle, not uniformly distributed

Rice and beans, concrete (you can see the different parts)

DensityMass per unit volume

Combustibility

Ability to burn in air

ethanol

Physical property

• A characteristic that can be observed or measured

Chemical property

• How a substance reacts when forming a new substance

Alloys

• Homogeneous mixture of one or more metals

Wood’s metal

Suspension

• Particles in mixture may be seen with naked eye or light microscope. Left undisturbed, particles separate.

Colloid

• A mechanical mixture with particles small enough they will not separate.

Tyndall effect

• The scattering of light by colloid particles

Compounds and Elements

Compounds: Atoms of different elements bonded together.Elements: Pure substances made of only one type of particle.