Classifying Matter

Elements An element is… The simplest pure substance One kind of material Definite properties Found on the Periodic Table of Elements

Compounds and Molecules A compound is… A pure substance One kind of material Definite properties Two or more elements chemically combined A molecule is the smallest particle of a compound that has all the properties of that compound Water is a compound H 2 O is a water molecule

Mixtures A mixture is… Matter Two or more substances Physically combined NOT chemically combined

Types of Mixtures Heterogeneous Mixtures Does not appear the same throughout Least Mixed Particles are large and easily separated Homogeneous Mixtures Appears to be the same throughout Well mixed Particles are small and not easily recognized

Types of Mixtures (cont) Heterogeneous Mixtures Homogeneous Mixtures

Solutions A solution is… A mixture Homogeneous Two or more substances A single physical state

Solutions (cont) Solvent – That part of a solution which doing the dissolving Solute – That part of a solution which is dissolved SoluteSolventSolution Gas Air GasLiquidSoda Water GasSolidAir Filters Liquid Antifreeze LiquidSolidDental Filling SolidLiquidOcean Water Solid Gold Jewelery

Solutions (cont) Law of Conservation of Mass Atoms cannot be created nor destroyed Mass cannot be created nor destroyed Change results in arrangement of elements Mass will remain constant H = amuH 2 O = amu H = amu O = amu

Testing Solution Chemistry ObjectCalculated Mass Measured Mass Notes Discuss things like dissolved, in settled on bottom, cloudy, any other observations Cup Cup ml water 100 ml water 100 ml water + 10 g salt 100 ml water + 20 g salt 100 ml water + 30 g salt 100 ml water + 40 g salt 100 ml water + 50 g salt

Testing Solution Chemistry (cont) Questions 1.Did your calculated (predicted) results equal your measured results? 2.Can you explain any differences? 3.In which scenarios were you able to get the salt to dissolve and in which did you have salt remaining at the bottom of the cup? 4.Did the amount of salt dissolved have any affect on your Conservation of Mass results? Use the following data about a 2-L bottle of Mountain Dew to answer Questions 5 through 8. Mass of Bottle =55.6Mass of Bottle + Soda = 2194 g Volume of Soda = 2000 mlMass of 2000 ml of Soda = g Mass of Sodium = 360 mgMass of Sugar = 276 g 5.The density of water = 1 g/ml. How much should 591 ml of water weigh? 6.How much (in grams) “stuff” is dissolved in the water to make it soda? 7.How much should a bottle of soda weigh? 8.Can you explain your observations and calculations?

Alloys An alloy is… A mixture A solution Two metals or A metal and a nonmetal

Suspensions A suspension is… A mixture Heterogeneous NOT a solution Two or more substances Particles large enough to settle and form a sediment

Ingredients and Procedure 2 parts corn starch 1 part water 1 – 2 drops of food coloring 1.Put corn starch in the cup 2.Add the food coloring 3.Slowly add water a few drops at a time and stir

Now for the science… Our cornstarch goo (sometimes referred to as “oobleck” from the Dr. Suess book) is what scientists call a “Non-Newtonian” liquid. Basically, Sir Issac Newton stated individual liquids flow at consistent, predictable rates. As you likely discovered, cornstarch goo does NOT follow those rules – it can act almost like a solid, and them flow like a liquid. Technically speaking, the goo is a SUSPENSION, meaning that the grains of starch are not dissolved, they are just suspended and spread out in the water. If you let the goo sit for an while, the cornstarch would settle to the bottom of the bowl. So why does this concoction act the way it does? Most of it has to do with pressure. The size, shape, and makeup of the cornstarch grains causes the cornstarch to “lock-up” and hold its shape when pressure is applied to it. People have filled small pools with oobleck and they are able to walk across the surface of it (as long as they move quickly.) As soon as they stop walking, they begin to sink.