What is the difference between Elements, Compounds & Mixtures? Unit 3 Structure and Organization of Matter

What ISN’T an Element? Earth, wind, fire and water are NOT elements! –Earth - most all substances on the periodic table –Wind - air is made up of multiple gases –Fire - is plasma, anything burning –Water - Hydrogen & Oxygen

What ARE Elements? Pure substances Any substance with a single kind of particle Those particles ALL have the same kind of atoms The particles cannot be divided further. Diamond = pure carbon

How are Elements Identified? Physical Properties –Boiling point –Melting point –Density Chemical Properties –Reactivity with acid –Reactivity with oxygen

How are Elements Categorized? By their properties –Physical & Chemical Three major types of elements –Metals –Metalloids –Non-metals

Draw a table like the one below StateAppearanceConductivityMalleablitity & Ductility Metals Non- metals Metalloids

What are Metals? Shiny, good conductors of heat & electricity Malleable - can bend Ductile - pulled into wire 95% of all elements are metals

The Metals

StateAppearanceConductivityMalleability & Ductility Metals -Solid at room temperature except Mercury -Shiny luster- Good conductors of both heat & electricity -All metals are malleable & ductile Non- metals Metalloids

What are Non-metals? Dull, not too shiny Poor conductors of heat & electricity Solids are brittle and break easily Not many solid objects are made up of non- metals

The Non-metals

StateAppearanceConductivityMalleability & Ductility Metals -Solid at room temperature except Mercury -Shiny luster- Good conductors of both heat & electricity -All metals are malleable & ductile Non- metals -Some gases at room temperature -Some solids -One liquid (bromine) - Not very shiny at all - Poor conductors of heat and electricity -Brittle - Not ductile Metalloids

What are Metalloids? They are semi-conductors –Some conduct electricity –Electrical conductivity is not as good as metals Have some properties of both metals & nonmetals –Shiny, metallic appearance Some are malleable & ductile

The Metalloids

StateAppearanceConductivityMalleability & Ductility Metals -Solid at room temperature except Mercury -Shiny luster- Good conductors of both heat & electricity -All metals are malleable & ductile Non- metals -Some gases at room temperature -Some solids -One liquid (bromine) - Not very shiny at all - Poor conductors of heat and electricity -Brittle - Not ductile Metalloids -Solids at room temperature -Some are very shiny -Some may conduct electricity -Poor conductors of heat -Brittle - Not ductile

What are Compounds? A pure substance made of 2 or more elements.

What else can be said of Compounds? Elements combine through a chemical reaction Elements don’t randomly form compounds Elements combine in a very specific ratio - based on the element’s mass

What are the properties of Compounds? Physical properties are similar to Elements: –Melting point, density, etc… Chemical properties can include: –Reactivity to oxygen –Reactivity to acid –Reactivity to light Caffeine

Light can break this compound down Can Compounds be broken down? Through a chemical change Most time a lot of energy must be added to cause the change –Heat –Electricity –Light

What are common Compounds? Common organic compounds include carbon, nitrogen, hydrogen and oxygen Such as those found in caffeine Theobromine - the active ingredient in chocolate

What is a Mixture? A combination of 2 or more substances that are NOT chemically combined

What is a Mixture? (continued) Two or more substances will not react together No chemical change occurs Each substance has the same chemical makeup in the mixture –Salt water The salt (NaCl) is still there as well as the water (H 2 O)

Can Mixtures be separated? Yes, through…. Distillation –Uses boiling points Evaporation –Atmospheric pressure Magnet –Removing iron Centrifuge –Uses the densities

Mixtures vs. Compounds Made of elements, compounds, or both No charge in original properties of components - not electrical Separated by physical means Formed using ANY ratio of components Made of elements only Change in original properties of components Separated by chemical means Formed using a set ratio of components

What about the ratio of components in a Mixture? Do not have to be mixed in any particular ratio Granite is an excellent example of this quality to mixtures

What is a solution? A mixture that appears to be a single substance Composed of 2 or more substances that are distributed evenly among each other Have the same appearance & properties throughout

What are parts to a solution? The process of particles separating spreading through a mixture is called dissolving Solute - the substance that is dissolved Solvent - the substance in which the solute is dissolved

What are examples of different Solutions? Gas in gas - – dry air, O 2 In N 2 Gas in liquid - –soft drinks, CO 2 in H 2 O Liquid in liquid - –antifreeze, alcohol in H 2 O Solid in liquid - –Salt water, NaCl in H 2 O Solid in solid (Alloy)- –brass, zinc in copper

What is Solubility? The ability of a solute to dissolve in a solvent, like… Putting sugar in water –Only so much sugar (solute) will dissolve in water (solvent)

What is the difference between Dilute & Concentrated Dilute solution contains less solute Concentrated solutions contain more solute

Dissolving gases in Liquids As the solvent (water) becomes warmer the gas becomes less soluble This is why a warm can of Mountain Dew will go “flat” faster. Gas that is dissolved in the water can’t stay dissolved as the temperature rises.

On the other side, however…

Dissolving Solids in Liquids Three ways to speed up the dissolving 1.Mixing/stirring (agitating) the solute in the solvent 2.Heating the solvent 3.Crushing the solute before placing it in the solvent 1 23

What is a Suspension? A mixture in which the particles are dispersed throughout but are large enough to settle out Heterogeneous Must be shaken or stirred periodically to remain mixed The suspension can be separated by use of a filter

Other Suspensions…

What are Colloids? Mixtures with properties in between solutions & suspensions Homogeneous Particles are dispersed throughout but are not heavy enough to settle out

Other Colloids….

Our Atmosphere is a mixture

Next up ….. The Periodic Table of the Elements!