Eighth Grade Science Mrs.Nelson

STARTER 1/17 and 1/18 Welcome Back! Distinguish between an element and a compound. Explain two identifying characteristics of each. Dissect the term subscript. Examine the prefix and root word. Predict what the term represents. STANDARD FOCUS: SPI 0807.9.1 Recognize that all matter is made of atoms. SPI 0807.9.3 Classify common substances as elements or compounds based on their symbols or chemical formulas. SPI 0807.9.9 Use the periodic table to determine the properties of an element.

4 Corners Corners are: 1. Element 2. Compound 3. Heterogeneous mixture Take the card you have been given. Determine the type of matter represented on your card. Move to the location which matches your material. Discuss with your group whether you belong. Remain or move based on group input. Prepare to defend your judgment. Corners are: 1. Element 2. Compound 3. Heterogeneous mixture 4. Homogeneous mixture

Matter Types Foldable Fold paper as instructed. Cut flaps on both sides. Label Record the following for each of the four matter types: Definition Examples with formulas Distinguishing characteristics

Can it be separated by physical means? A. Matter Flowchart MATTER yes no Can it be separated by physical means? PURE SUBSTANCE MIXTURE Is the composition uniform? no yes Can it be decomposed by chemical means? no yes Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element

Pure Substances Element matter composed of identical atoms EX: copper, Au

Pure Substances Compound matter composed of 2 or more elements in a fixed ratio properties differ from those of individual elements EX: salt (NaCl)

Mixtures Homogeneous Mixture (Solution) Variable combination of 2 or more pure substances. Homogeneous Mixture (Solution) even distribution of components very small particles particles never settle EX: saline solution

Mixtures Heterogeneous Mixture uneven distribution of components Can see all components EX: trail mix

Chemical Formulas Shorthand method to name pure substances. Always show the fixed composition Never applied to mixtures- WHY?

What is it? Elements are simply represented by their symbol. When two different atoms bond they make a compound. A chemical formula names the new substance that is made. Ex: Na and Cl make Sodium Chloride New substances have new characteristics. Shorthand way to write names is used in science. NaCl is the chemical formula for sodium chloride.

NaF2 Parts and Pieces Element symbols represent the elements present Subscripts are those little numbers attached to symbols- they cannot ever change NaF2

Compound and molecule vs element You can read a chemical formula to determine the nature of a substance Compounds show more than one item by multiple symbols or subscripts CO2, H2O, HCl You can identify a single element by seeing just one symbol or lack of subscripts. Ag, N, Cu

STOP and THINK Remember: Elements are pure substances made of only one type of atom. Compounds are unique substances too, but with two or more atoms chemically bonded together. Mixtures have no real set composition, no bonds, and can be physically separated. Chemical formulas are like recipes to determine the composition of a compound.

SUMMARY Pt O O2 Water Air Salt water Identify the following in your journal as mixture, element, or compound. Pt O O2 Water Air Salt water