University:
Winston-Salem Forsyth County Schools
Course:
AP Physics I
Academic year:

2014
Views:

54

Pages:

25
Author:

Raelynn Roy

Classification of Matter Physical Science What is Matter????? ANYTHING, that has mass and volume (takes up space) HOW WOULD YOU CLASSIFY THESE TYPES OF MATTER?  How would you sort these: A bin of markers?  A deck of cards?  A lot filled with new cars? How Do We Classify Matter in Science?????     Scientists like to classify things. It wouldn’t help too much to just classify matter based on their color or smell…. One way that scientists classify matter is by its composition (what it is made of). Ultimately, all matter can be classified as Mixtures or Pure Substances. Classifying MATTER- we must start by knowing that ……. The building blocks of all matter are elements (like on the periodic table) Atoms are the smallest unit of an element that maintains the properties of that element For example, one atom of gold (Au) is still gold, but if you broke the atom into smaller pieces, it wouldn’t be gold Pure Substances An Element is a pure substances made of only one type of atom For example, O2 C Ca He 7 Pure Substances Compounds A compound is a substance that is made from the atoms of two or more elements that are chemically combined. Examples: NaCl (salt) H2O (water) Classification of Matter by Composition All matter can be classified into two categories: Pure Substances or Mixtures 9 Pure Substances ELEMENT 10 Classification of Pure Substances COMPOUND 11 Classifying Mixtures Mixtures Homogeneous (Solutions ) Heterogeneous Colloid Sus pens ion Classification of Mixtures homogeneous = mixture that has uniform composition throughout AKA: Solution Every piece of a sample has identical characteristics, though another sample with the same components may have different characteristics. atoms or molecules mixed uniformly 13 Page 450 Put the following definitions in your notebook from the book: Element Compound and give example Heterogeneous Mixture Colloid and give example Suspension and give example Homogeneous Mixture Then turn over the paper I gave you and complete Homogeneous Mixtures (Solutions) • Solutions – Appear Uniform – Mixed particles are dissolved and so small that they don’t reflect light (scattering). – Nothing settles out over time. – Nothing filters out. – Can be in solid, liquid, or gas form! Examples of homogeneous mixtures Milk, toothpaste, and mayonnaise are homogeneous mixtures. Classifying Mixtures Mixtures Homogeneous (Solutions ) Heterogeneous Colloid Sus pens ion Classification of Mixtures heterogeneous = mixture that does not have uniform composition throughout– you can see the different parts contains regions within the sample with different characteristics atoms or molecules not mixed uniformly 18 Heterogeneous mixtures You can see the particles that make it up.    Sand and pebbles Oil and water Cereal Heterogeneous Mixtures – 2 types Heterogeneous • Colloids – Looks uniform but particles aren’t really dissolved. Particles are still large enough to scatter light. Looks cloudy when light goes through it. • Suspensions – Don’t look uniform, filters, settles out over time, and particles scatter light. Heterogeneous Mixtures – 2 types Heterogeneous or solution (homogeneous)? • How can we tell if a mixture is truly homogeneous or heterogeneous? • SHINE A LIGHT THROUGH IT AND YOU WILL KNOW! Tyndall Effect This is the scattering of light reflecting off little particles. Solution: cannot see beam of light Heterogeneous: you can see beam of light (reflecting off litte particles) Density Density – More dense objects will sink when compared to less dense objects. What do you think has the highest density? WATER, OIL, MOLASSES? Density Density – How much matter is contained in a certain volume D=mass/volume What is more dense, a cup of unpopped popcorn kernels or a cup of popped popcorn? Bellringer 11-12-13 1. A lot of medicines are kept in dark brown bottles (not clear) What kind of change (do you think) is being prevented by keeping the sunlight out? Physical or Chemical 2. If you let saltwater evaporate, the salt is left behind. This is a method of making drinking water from sea-water called desalination. Is this a physical or chemical change?