Chapter 2 Matter & Change Standards: INQB, Matter consists of atoms that have internal structures that dictate their chemical and physical behavior. Targets: Distinguish between physical and chemical properties Distinguish between physical and chemical changes Distinguish between elements, compounds, and mixtures

Distinguish between physical and chemical properties Physical property A characteristic of a substance that can be measured or observed without changing the substance’s composition Chemical property The ability of a substance to undergo a chemical reaction to form new substances

Distinguish between physical and chemical properties Examples of Physical Properties Color Solubility (Dissolving) Odor Hardness Density Melting Point Boiling Point State of matter Thermal capacity Mass Examples of Chemical Properties Reactivity with oxygen Reactivity with acids Reactivity with bases Reactivity with other elements Sodium and Chlorine Reaction

Distinguish between physical and chemical properties Sodium is a silver metal at room conditions; combines with chlorine to make table salt; reacts with water to form hydrogen; has a density of 0.93 g/cm 3 ; oxidizes rapidly in air, melts at 97.8 o C. Using the above description, list the physical properties of sodium Using the above description, list the chemical properties of sodium

Distinguish between physical and chemical properties Sodium is a silver metal at room conditions; combines with chlorine to make table salt; reacts with water to form hydrogen; has a density of 0.93 g/cm 3 ; oxidizes rapidly in air, melts at 97.8 o C. Using the above description, list the physical properties of sodium Using the above description, list the chemical properties of sodium

Distinguish between physical and chemical changes Physical change An alteration of matter that does not change the chemical composition of the material. Chemical change Results in a change in the chemical composition of the substance(s). This is called a reaction.

Distinguish between physical and chemical changes Examples of Physical Changes Freezing or melting Boiling or condensing Cutting Grinding Bending Blending Dissolving Examples of Chemical Changes Combustion (burning) Reacts with an acid Reacts with a base Rusting Oxidizing Decomposing Digesting

Distinguish between physical and chemical changes Copy the statement on your paper and write P for physical or C for chemical 1.Bending of a piece of wire 2.Burning of coal 3.Cooking a steak 4.Cutting grass 5.Sodium reacts with water 6. Iron rusts 7. Silicon is insoluble in water 8. Ice melts 9. Neon boils at C 10. Nitric Acid reacts with Copper

States of Matter StateShapeVolume Expansion when heating Compressibility Solid (S) Definite Very slightly Almost incompressible Liquid (l) IndefiniteDefiniteModerate Almost Incompressible Gas or Vapor (g) Indefinite Great Readily compressible

Distinguish between elements, compounds, and mixtures Elements are composed of just one type of atom. They cannot be separated into simpler substances using chemical means. Compounds are substances composed of two or more different kinds of atoms that have combined chemically. They can be separated by chemical means. Mixtures are a physical blend of two or more substances. They can be separated by physical means.

Distinguish between elements, compounds, and mixtures Elements –Represented by a chemical symbol (see Periodic Table) –Gold (Au), Iron (Fe), Oxygen (O or O 2 )

Distinguish between elements, compounds, and mixtures Compounds –Represented by a chemical formula that shows the elements and relative number of atoms in the compound. –Examples: Water, H 2 O, contains 2 atoms of hydrogen (H) and one atom of oxygen(O). Salt, NaCl, contains one atom of sodium (Na) for each atom of chlorine (Cl).

Distinguish between elements, compounds, and mixtures Mixtures: Heterogeneous mixture – One that is not uniform in composition and appearance. –Ex: soup, concrete, granite Homogeneous mixture- One that is uniform in composition, also called solutions. –Ex: air, river water, syrup

Distinguish between elements, compounds, and mixtures Ways to separate mixtures: –Heterogeneous: sieving, tweezers, skimming –Homogeneous: distillation, ion exchange, reverse osmosis, evaporation

Distinguish between elements, compounds, and mixtures Copy the item and indicate if it is an element, compound or mixture 1.Blood 2.Hydrogen 3.Brass (copper and zinc) 4.Ice 5.Motor oil 6. Silver 7.Orange juice 8.Neon 9.Sugar 10. Lake water

Distinguish between physical and chemical changes In a chemical reaction, one or more substances change into new substances by rearranging the atoms Reactants  Products Copper+ nitric acid  copper(II) nitrate+ nitrogen dioxide+water

Distinguish between physical and chemical changes How to tell a chemical reaction has occurred: –Heat is absorbed or given off. –Change in color or odor. –Production of a gas or solid. –Not easily reversible.

Distinguish between physical and chemical changes Law of Conservation of Mass –During any chemical reaction, mass is neither created nor destroyed, it is conserved. –The mass of the products will always equal the mass of the reactants. –The mass of each element is also unchanged.

Distinguish between physical and chemical changes Law of Conservation of Mass In the reaction where hydrogen reacted with oxygen to produce water; if 4.5 grams of hydrogen and 34 grams of oxygen were used, how many grams of water was produced? Hydrogen + oxygen = water 4.5g + 34g = 38.5g water