Elements, Compounds, and Mixtures Now that we have learned about the development of the atom, the structure of the atom, and how elements are arranged on the periodic table. This chapter we are going to compare and contrast elements compounds, and mixtures. We are going to focus on the difference between pure substances and mixtures and what category does everything fall into.

Matter can be classified into elements compounds, and mixtures. SECTION 1: Elements Matter can be classified into elements compounds, and mixtures. Matter can be classified into elements, compounds, and mixtures. Tonight we will focus on the first type of particle…the element.

Elements, the Simplest Substances An element is defined as a pure substance that cannot be broken down into simpler substances by chemical or physical means. A pure substance is a substance that contains only one kind of particle. An element contains only one kind of particle (an atom).

Properties of Elements Each element can be identified by its unique properties. These properties are referred to as characteristic properties. (ex: magnetic, radioactivity, density, melting point, etc) Characteristic properties include BOTH physical and chemical properties.

Classifying Elements by Their Properties Elements are grouped into categories according to the properties that share. There are three major categories of elements. Metals-shiny, conducts heat and electricity, malleable, ductile (found on the left and in the center of the periodic table) Non-metals-dull, non-conductors, brittle (found on the right side of the periodic table) Metalloids-have properties of both metals and non-metals(located along the “staircase/zigzag between metal and non- metals.

SECTION 2: Compounds Because most elements easily change chemically, they are rarely found alone in nature.

Compounds: Made of Elements A compound is a pure substance that is made of 2 or more elements that have combined chemically. A particle of an element is an atom. A particle of a compound is a molecule. When elements join to form a compound, they do so in a specific ratio based on their masses (we are interested in the ratio of the number of atoms H2O is a ratio of 2 H to 1 O)

Properties of Compounds Compounds have physical and chemical properties. A compound’s properties are different than the properties of the elements that came together to make the compound.

Breaking Down Compounds Some compounds can be broken down by chemical changes into the elements that make them. Some compounds do not break down into their elements, but into other simpler compounds. Chemical changes are required to break down compounds. The addition of energy may be necessary to cause the chemical change. Energy can be added by applying heat or an electric charge.

A mixture can contain elements and compounds. SECTION 3: Mixtures A mixture can contain elements and compounds.

Properties of Mixtures A mixture is defined is a combination of 2 or more substances that are not chemically combined. No chemical change happens when a mixture forms. Each substance in a mixture keeps its identity. With a mixture, you may or may not be able to see the substance making it. Mixtures can be separated by physical means such as boiling or filtering. The components of a mixture are not necessarily in a specific ratio like a compound.

Solutions-Homogeneous Mixtures A solution is a mixture that appears to be made of just one substance, but in fact is composed of different substances. The substances making up a solution are evenly distributed among one another. The process by which substances evenly disperse is known as dissolving. The solute is the substance that is dissolved, or dispersed between the particles of the solvent. The solvent is the substance in which the solute dissolves.

Solutions-Homogeneous Mixtures A solute must be soluble to dissolve. If a substance is insoluble, it forms a heterogeneous mixture, not a solution. Solutions may be liquids, gases, or solids. With a solution, the particles of the solute are so small they never settle out of the solution and do not scatter light. Solutions will NOT separate into parts by filtering. Examples of Solutions: salt water, lemonade, sugar water, sweet tea, air, brass, and bronze.

Concentrations of Solutions Concentration is a measure of the amount of solute dissolved in a solvent. Solutions will either be concentrated or diluted. If a solution is concentrated, there is a lot of solute in the solvent. If the solution is diluted, there is not a lot of solute in the solvent. The solubility of a solute is the ability of the solute to dissolve in a solvent at a certain temperature. Most solutes dissolve more easily at higher temperatures. Heating, mixing, and crushing the solute will cause the solute to dissolve faster. You cannot change a substances solubility it is either soluble or not.

Concentrations of Solutions UnSaturated-there is way less solute than solvent Saturated-there is an equal amount of solute to solvent SuperSaturated-there is more solute than solvent

A mixture can contain elements and compounds. SECTION 3: Mixtures A mixture can contain elements and compounds.

Suspensions- Heterogeneous Mixtures A suspension is defined as a mixture is which particles of a material are more or less evenly dispersed throughout a liquid or gas. The particle in a suspension are large enough that they settle out and scatter light. The particles are so large that they suspension must be shaken or stirred to stay mixed. A suspension can easily be separated into the substance that makes it up by filtering. Examples include: Snow Globe, Italian Dressing, Dirty Water

Colloids- Heterogeneous (kind of) Mixtures A colloid is defined as a mixture in which the particles are smaller than a suspension and dispersed pretty evenly among each other. The particles in a colloid are so small that they take a long time to settle out. The particles in a colloid will scatter light. Filtration will not separate the particles of a colloid because the particles are too small to be caught in the filter. Examples include: Gelatin, Milk. Mayonaise

Next time in class… We will discuss the information presented tonight. We will work on flashcards during that discussion. We will also complete an activity on this content. Those who have not completed the notes will not be able to participate in the activity until they do.