Chapter 4 Science Test Review PDF

Chapter 4 Review MATTER: Matter: anything that occupies space, has mass, is made of particles, and is one of 3 or 4 forms (solid, liquid, gas, plasma). TYPES OF MATTER: Pure Substance: Matter that is composed of only one kind of particle. Mixture: Matter that is composed of many kinds of partic...

Chapter 4 Review MATTER: Matter: anything that occupies space, has mass, is made of particles, and is one of 3 or 4 forms (solid, liquid, gas, plasma). TYPES OF MATTER: Pure Substance: Matter that is composed of only one kind of particle. Mixture: Matter that is composed of many kinds of particles. TYPES OF PURE SUBSTANCES: Element: A pure substance that is composed of only the same kind of atom. It cannot be broken down further by chemical or physical methods. Ex. O2 (Oxygen), N2 (Nitrogen), H2 (Hydrogen), C (Carbon), Ca (Calcium), Fe (Iron), Mg (Magnesium) Compound: A pure substance that is composed of only the same kind of molecule. It can be broken down into its elements only by chemical methods. Ex. H2O (Water -- Hydrogen and Oxygen), C6H12O6 (Glucose - 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms for every molecule), Table Salt (NaCI - Sodium and Chloride) TYPES OF MIXTURES: Mechanical Mixture: A mixture that visibly has many kinds of particles. Ex. Salad, Toolbox Solution: A mixture where one substance is dissolved in another, and the different kinds of particles are not visible (typically types of liquids). Ex. Salt Water PHYSICAL PROPERTIES: Physical Property: a characteristic of a substance that you can observe and measure without changing the identity of the substance. TYPES OF PHYSICAL PROPERTIES: QUALITATIVE: a property that can be observed and described without detailed measurement. Colour -- colourless, red, black Odour -- sweet, pungent, mouldy State -- solid, liquid, gas, plasma Texture -- rough, smoot, bumpy Lustre -- shiny, dull Malleability -- soft, pliable, hard QUANTITATIVE: a property that can be measured and assigned a particular value. Viscosity -- resistance to flow (Ex. oil is more viscous than water) Melting Point -- temperature when a solid turns into a liquid (Ex. 0 degrees Celsius turns ice to water) Boiling Point -- temperature when a liquid turns into a gas (Ex. 100 degrees Celsius turns water to steam) Solubility -- how much mass dissolves in a solvent (Ex. 39.5 g/100 mL salt in water) Hardness -- ability to scratch (Ex. glass is harder than skin and a diamond is the hardest substance) Conductivity - ability to conduct electricity (Ex. copper has a high conductivity and wood has a low conductivity) Density -- the mass of a substance that occupies a certain volume (10.5g/cm3) CHEMICAL PROPERTIES: Chemical Property: the ability of a substance to react with another substance and form one or more new substances. TYPES OF CHEMICAL PROPERTIES: Combustibilty: the ability of some substances to burn in air. (Ex wood is combustible and concrete is not combustible) Stability: how easy or difficult it is to break down a substance. The more stable a substance is, the longer it will take to break down. (Ex. DDT is highly stable -- bioaccumulation) For scientists who focus on trying to synthesize new chemicals, stability is often an issue they must deal with. For a chemical to be useful, it must have enough stability to exist long enough to carry out its required function. Toxicity: the harm that exposure to a substance can cause to plants to animals. Almost all chemicals are poisonous at high enough concentrations. For example, you need oxygen to breathe but too much will kill you. Therefore, it is important to know how toxic a chemical is. For example, the toxic effects of DDT are made worse by its stability, If DDT easily broke down, then it would not bioaccumulate and biomagnify, and its toxic effects on animals and humans would be lower. CHANGES: Physical Change: the material involved in the change is structurally the same before and after the change. Types of some physical changes are texture, shape, temperature, and a change in the state of matter. Chemical Change: a change of materials into another where one or more new substances are formed. Difference: A physical change only alters the appearance or form of a substance, while a chemical change creates a new substance with different properties. TYPES OF CHEMICAL CHANGES: Reactivity with Water: Ex. Calcium Carbide reacts with water and produces acetylene, which is highly flammable. This is used in welding and was used in miner's lamps in the past. Reactivity with Oxygen (combustion): Ex. Propane burns in oxygen to produce water and carbon dioxide. This is used in BBQ grills and hot air balloons. Reactivity with Acids: Ex. Sodium Bicarbonate (baking soda) reacts with acetic acid (vinegar) to produce carbon dioxide. This is used in household cleaning. Reactivity with Other Substances: DENSITY: Density: the mass of a substance that occupies a certain volume. Problems on paper