Matter and Change

Matter Matter is anything that has mass and takes up space. Stuff! There are three basic states of matter: Solid (s) has definite shape and volume Liquid (l) shape can change, still has definite volume Gas (g) no definite shape or volume Draw a representation of the states of matter here.

Phase Changes Matter can change from one state (or “phase” to another) There are six possible phase changes. Energy is either absorbed or released. Freeze, sublimate, condensation melt evaporate, deposition . Deposition

Energy The universe consists of matter and energy. Energy does not have mass or take up space. Energy is involved when matter changes from one state to another. Solid + Energy  Liquid “Melting” Example: Ice (s) + heat energy  Water (l)

Energy Changes Endothermic- a process which requires, or absorbs energy. (Feels cold in chemical changes) Ex: H2O (s) + energy  H2O (l) Ex: Melting, evaporating, boiling Ex: baking soda reacts with acid Exothermic- a process which releases or gives off heat. (Feels hot in chemical reactions) Gasoline burns and releases heat Exercising muscles produces body heat Ex: freeze, condensation

Classification of Matter There are two kinds of matter: Pure Substances (elements and compounds) Mixtures Elements- are pure substances Can’t be broken down by ordinary means Are found on the Periodic Table Usually found as single atoms Some gaseous elements exist as two atoms bonded together (The HOFBrINCl gases) like O2

Compounds Compounds- are also pure substances Can be broken down by chemical reactions only Are made up of two or more elements chemically combined, or “bonded” Always have a chemical formula that doesn’t change The compound has new properties, not the same as the original elements. .

Examples of Pure Substances Elements: Carbon Oxygen Gold Neon About 100 more! (If you are not sure, check the periodic table.) Compounds: Water, H2O Sodium chloride, NaCl Hydrogen peroxide, H2O2 Methane, CH4 Baking Soda NaHCO3 Glucose C6H12O6 There thousands and thousands of known compounds! (If it has a chemical formula, it’s a compound.)

Compare: Element, compound or mixture?

ANSWERS: Element, compound or mixture?

Mixtures Mixture- a physical combination of two or more substances. A mixture can be separated by physical means The components of the mixture retain (keep) their original properties The composition can vary (for example. A mixture could be 50% A and 50% B, or it could be only 30% A and 70% B.)

Examples of Mixtures Salt water ( H2O and NaCl) Sugar water ( H2O and C12H22O11) Air ( Nitrogen, Oxygen, and trace elements) Brass ( copper and zinc combine to form an alloy)

Mixtures There are two kinds of mixtures. Homogeneous mixtures: Appear uniform, or the same, throughout Also known as solutions Heterogeneous mixtures: Not uniform in appearance or composition

Examples of Mixtures Heterogeneous: Soil Homogeneous: Sand and water mixture Sometimes you must look very closely, or even magnify to see the different parts. Homogeneous: Air Salt water Sugar water Brass Solutions

Separation of Mixtures Mixtures can be separated by physical means. Physical means include: Filtration separates components based on their size Distillation separates components based on their different boiling points Chromatography separates based on differences in solubility Pictures of these on the next few slides…..

Filtration Filtering apple cider

Distillation

Chromatography

Physical and Chemical Changes Physical Change- Is usually reversible (can be undone) All phase changes are physical changes List the six phase changes here: (s)  (l) melting and (l)  (s) freezing (l)  (g) evaporation (s) (g) Sublimation (g)  (l) Condensation (g)  (s) Deposition Dissolving is a physical change Shape changes are physical changes (such as: tearing, bending, etc.)

Physical and Chemical Changes Always produces a new substance The new substance will have different properties Evidence of Chemical Change Color change Bubbles of gas appear A new solid forms (a “precipitate) Temperature change

Chemical Changes Chemical Changes are also called chemical reactions. Chemical reactions always produce a new substance: Rusting Burning Cooking Digesting There are many more!

Chemical Reactions A + B ------------- > C reactants yields products Chemical reactions must obey the Law of Conservation of Mass: The mass of the products must equal the mass of the reactants. In other words, matter is neither created nor destroyed 5 grams of A + 5 grams of B yields 10 grams of C

Properties A property is something you can observe or measure. There are two types of properties, physical and chemical.

Physical Properties Physical properties can be measured or observed without changing or destroying the sample Examples of physical properties Mass Color Density Melting and boiling points Ductility (can make wire) and malleability (flexibility)

Physical Properties There are two types of physical properties Extensive- these depend on the amount of the substance. (Mass, length, and volume) Intensive- stay the same no matter what the amount of the substance is. (Color, density, conductivity, etc.)

Chemical Properties Chemical Properties- how a substance reacts with other substances Reacts with water Reacts with oxygen Reacts with whatever Even if it doesn’t react, that is also a chemcial property These are easy to recognize, always “React”

Chemical Properties Corrosive Flammability Oxidizes Solid Oxidizer Test : measures the potential of a solid substance to increase the burn rate or intensity of a combustible substance Nonflammable Clothing