Elements, Compounds & Mixtures! Mr. Coffey

What are Elements? An element is a pure substance that cannot be separated or broken down into simpler substances by physical or chemical means. What are examples of elements? Anything that is on the Periodic Table of Elements. Examples: Gold (Au), Silicon (Si), Neon (Ne), Silver (Ag), sulfur (S) S Au Ag Fe

The Periodic Table of Elements Everything that is on this table is an element. If it isn’t on this table, it isn’t an element!

Pure Substances Pure substances are substances in which there is only one type of particle. These particles are called atoms. The only two things that are pure substances are: 1. Elements 2. Compounds

Identifying Elements Elements are categorized by unique properties on the Periodic Table. They are arranged in order by their number of protons. (More on this later!) Each element has unique properties like melting point, boiling point, and whether it is metal, nonmetal or metalloid.

What are compounds? A compound is a pure substance composed of two or more elements chemically combined. This means they were formed by a chemical reaction. Elements Compounds

Familiar Compounds Compound Elements Combined Formula Table salt Sodium and Chlorine NaCl Water Hydrogen and Oxygen H2O Vinegar Hydrogen, Carbon, and Oxygen C2H4O2 Carbon dioxide Carbon and Oxygen CO2 Baking soda Sodium, Hydrogen, Carbon and Oxygen NaCHO3

ELEMENTS MAKE COMPOUNDS!! Forming a Compound Compounds are formed by combining two or more elements. Elements are “stuck together” by chemical bonds When this happens, new properties are formed; the elements lose their original properties. You end up with one new thing! ELEMENTS MAKE COMPOUNDS!!

Example: Formation of NaCl + Sodium Chloride, or table salt, is a white solid. It dissolves easily in water and is safe to eat. Sodium is a soft, silvery white metal that reacts violently with water. Chlorine is a poisonous, greenish-yellow gas. **Compounds have properties that differ from those of the elements that form it!**

How are compounds separated? Compounds are broken apart by breaking chemical bonds. You separate them by forcing another chemical reaction to happen CHEMICAL CHANGE!!!! Add heat, electricity, another compound or element as a chemical reaction Remember compounds are specific recipes! They have a fixed ratio!

Breaking Chemical Bonds

What is a mixture? A mixture is when 2 or more substances are combined but do not chemically react. THE SUBSTANCES KEEP THEIR OWN PROPERITES!! We say that we MIX to form them.

Examples of Mixtures Iced tea powder and water Granite Milk Oil and vinegar

3 Properties of a Mixture It is NOT a chemical change It can be separated by physical means Ratio of each substance does NOT matter

Separation of a Mixture Pick apart or straining Evaporation Filter Centrifuge Distillation (boiling the solvent to separate it from the solute) Magnetism (like iron)

Separating a mixture is a PHYSICAL CHANGE because there are no chemical reactions or changes - parts keep their properties!!

Types of Mixtures Homogeneous (Homo = same) Heterogeneous (Hetero = different) The mixture appears to be the SAME throughout The mixture appears to be DIFFERENT throughout

Examples HOMOGENEOUS Milk Stainless steel Oil Brass (Cu + Zn) HETEROGENEOUS Oil & vinegar Concrete Soil Pizza, Cereal

YES NO YES: NO: YES: NO: All matter Can it be separated by physical means? Mixtures Pure substances Is the composition uniform? Can it be decomposed by ordinary chemical means? YES: NO: Homogeneous Mixtures (air, sugar in water, stainless steel) YES: NO: Heterogeneous Mixtures (granite, wood, blood) Compounds (water, sodium chloride, quartz) Elements (gold, aluminum, oxygen, chlorine) DIFFERENT THROUGHOUT SAME THROUGHOUT

How are Mixtures and Compounds Different Made of 2 or more substances physically combined Keep their own properties Can be separated by physical means Have no definite chemical composition Made of 2 or more substances chemically combined. Substances lose their own properties. Can be separated only by chemical means. Have a definite chemical composition.