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Science 9 Unit 2- Matter and Chemical Change Topic 1- Exploring Matter Chemistry • The study of the properties of matter and the changes matter undergoes • Much of what we know today was not discovered in fancy labs using expensive equipment • Many scientists were very poor and dedicated their lives to research without pay Safety in the Lab • Some scientists in the past routinely tasted and smelled chemicals which is extremely dangerous • some chemicals are caustic and can burn, corrode, or destroy organic tissues • The chemicals, equipment, and procedures used in the lab must always meet safety guidelines such as wearing the appropriate equipment Classifying Matter • The Particle Model of Matter: 1) All matter is made up of tiny particles 2) Each pure substance is its own particle, different from other particles of other substances 3) Particles attract each other 4) Particles are always moving 5) Particles at higher temperatures move faster than particles at low temperatures The Particle Model • Scientific models help us to visualize the processes that cannot be seen directly • Matter can be classified according to its state as a solid, liquid, or a gas Chemical Composition • Matter can be further classified according to its composition as a mixture or a pure substance. Mixtures contain at least 2 substances and a pure substance is its own kind of particle • Mixtures can be classified as homogenous (particles uniformly scattered) and heterogeneous (not uniformly scattered) Mixtures of Matter • Solutions are homogenous mixtures that are usually clear and can not be separated • Mechanical mixtures are heterogeneous mixtures where the parts are large enough to see • Suspension is a heterogeneous mixture made of large particles that are uniformly mixed but will settle if left undisturbed-ex. Flour in water • Colloids are composed of fine particles evenly distributed throughout a second substance- ex. Hair gel and clouds • Emulsions are colloids where liquid is mixed in liquid ex. Mixed up oil and vinegar salad dressing Spot the Mixture??