Chemical Foundations Review – Day 1

What is Chemistry? Chemistry is the science that deals with the “properties” of matter. What are “chemicals”? Areas of chemistry: –Organic: all compounds that contain carbon –Inorganic: compounds with no carbon –Biochemistry: chemical reactions in living things (example?)

Classification of Matter MATTER (gas. Liquid, solid, plasma) PURE SUBSTANCES MIXTURES HETEROGENEOUS MIXTURE HOMOGENEOUS MIXTURES ELEMENTSCOMPOUNDS Separated by physical means into Separated by chemical means into Kotz & Treichel, Chemistry & Chemical Reactivity, 3 rd Edition, 1996, page 31

Matter Pure Substance Single composition Pure Substance Single composition Element [Periodic Table-One Type of atom] (Examples: iron, sulfur, carbon, hydrogen, oxygen, silver) Element [Periodic Table-One Type of atom] (Examples: iron, sulfur, carbon, hydrogen, oxygen, silver) Mixture of Substances Variable composition Mixture of Substances Variable composition Compound More than one type of atom (Examples: water. iron sulfide, methane, aluminum, silicate) Compound More than one type of atom (Examples: water. iron sulfide, methane, aluminum, silicate) Homogeneous mixture One Phase throughout, also called a solution (Examples: air, tap water, metal alloy) Homogeneous mixture One Phase throughout, also called a solution (Examples: air, tap water, metal alloy) Heterogeneous mixture More than One Phase distinct phases (Examples: soup, concrete, granite) Heterogeneous mixture More than One Phase distinct phases (Examples: soup, concrete, granite) Chemically separable Physically separable

Solid, Liquid, Gas (a) Particles in solid (b) Particles in liquid (c) Particles in gas

The Periodic Table

Elements, Compounds, and Mixtures (a) an element (hydrogen) (b) a compound (water) (c) Solution: a mixture (water and Salt ) (d) Mechanical: a mixture (water and Oil) Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 68

Diatomic Elements Have: H 2 No:N 2 Fear:F 2 Of:O 2 Ice:I 2 Cold:Cl 2 Beer:Br 2

All Matter can be further classified into their properties Physical Properties Properties that can observed or measured without any change to the substance State Colour Density Clarity Lustre Viscosity Malleability Chemical Properties Properties that describe an action while the substance changes Flammability Combustibility Corrosion Rusting Hardening

Identify the following as Physical or Chemical Properties The density of aluminum is 45g/cm 3 Milk is opaque The copper bucket turned green because Jamie left it outside. Laura’s solution was blue and very thick The temperature of the mixture rose 6 degrees The paint dried into a shiny surface.

Observations of Properties Qualitative An observation that uses one or more of the 5 senses (see, hear, touch) Eg: The solution turned blue Or: the mixture had a strong odour Quantitative An observation that relies on measurement or numerical values. Eg: The object weighed 3.6g. Or: The temperature of the water rose 4.6°C

CHANGES TO MATTER PHSYICAL CHANGE No New substance has been created! Example: evaporation of water, changes liquid into gas state…but it is still water! H 2 O (l) → H 2 O (g) CHEMICAL CHANGE A new substance has been created! Example: Iron metal reacts with Oxygen to produce “Rust” 2Fe (g) + 3O 2(g) → 2Fe 2 O 3(s)

Clues that a chemical reaction has occurred 1.A new colour appears 2.A new solid appears 3.A new gas appears 4.Heat and/or light is produced or absorbed 5.The change is irreversible.

Identify the following as a physical or chemical change… Condensation appeared on the glass The silver spoon tarnished I put Hersey’s syrup in my milk. The moth ball disappeared quickly The acid rain ate away at the metal parts I cut the carrots into slices Julie mixed the blue solution with the green solution and dark precipitate formed

Conservation of Matter Reactants yield Products

Balanced Equations in Chemistry sodium + water  hydrogen + sodium hydroxide 2 Na(s) + 2 H 2 O(l)  H 2 (g) + 2 NaOH(s) Let’s visualize what’s happening at the “particle level”… What happens to the particles during a chemical reaction? They are NOT created or destroyed; they are merely rearranged Is there a change in energy associated with a chemical change? Yes: heat, light, sound - perhaps not easily noticed