 Intro to Chemistry Chapter 1 and Chapter 2 A Preview of Coming Attractions

 ONLY INTENDED FOR MATURE STUDENTS! RIGOROUS

The Ancient Greeks ~ 400 BC  Aristotle suggested that everything was composed of 4 elements:  Water, Air, Earth and Fire  He later added a 5 th element which he called “aether” which the stars and the heavens were made from.  Aristotle also said that “cold” was a substance he called primum frigidum, and that “cold” came from water.  People actually believed this up until the middle ages (1500s at least).  Click on the next slide to see three of these “ancient elements.”

Earth Wind & Fire ( Yes, I’m “old school.” But I love these guys. And, I even saw them in concert once, back in the 80’s. OK, back to chemistry on the NEXT slide…If you don’t some Earth Wind and Fire on your “playlist,” get some. Tonight. Seriously.

Notes are not optional! CUES 1-2 words CUES Main part for Notes.. Use bullet points... Abbreviate.. Draw pictures to. help you... You do not have. to write in. complete. sentences. Main Part for Notes

The Law of Conservation of Mass  In any chemical reaction or physical change, matter can neither be created nor destroyed (page 50)  The amount of matter (mass) doesn’t change.  However, the identity of the matter (what type of substance it is) could change.  mass of the reactancts = mass of the products (this is a statement of the law in math form, using an equation)

Chapter 2. Big Idea = Chem as a Central Science  Back to matter…matter has mass and volume.  Intensive property—depends on the type of matter.  Extensive property—depends on the amount of matter.  Matter can be broken down into substances and mixtures.  Substances are pure.  Elements (smallest part of an element is an atom)  Compounds (smallest part of a compound is a molecule)  Mixtures of substances. NOT bonded together.  Mixtures are either homogeneous or heterogenous.

Physical Properties  Matter has both physical and chemical properties.  Physical properties can be observed without CHANGING the type of matter.  When solid water (ice) melts it becomes liquid water. A change of state is a physical change ( Δ or delta means change).  Physical changes are NOT permanent and are reversible.

Chemical Properties  Chemical properties can be ONLY be observed BY CHANGING the type of matter.  Chemical properties are permanent and not reversible.  When salt is dissolved in water, a solution is formed. That is a physical change. The salt is still salt and the water is still water. You can separate them easily by evaporating the water.

Chemical Properties  But when sodium oxide (Na 2 O) is dissolved in water it dissolves, but then a chemical reaction occurs. That is a chemical change.  Sodium oxide has different chemical properties compared to salt, and so it reacts differently.  We write the reaction as Na 2 O + H 2 O  2 NaOH  That’s your first chemical “sentence.” The reaction describes a chemical change. You need to be able to identify a property or change as being either chemical or physical for the first test!

States of Matter  Solid *  Liquid *  Gas *  A vapor is a substance that is generally solid or liquid at room temperature, but is in the gaseous state (like steam or water vapor).  You don’t need to know these, but they do exist:  Plasma  Only observed at extremely high temperatures (several thousand degrees)  Bose-Einstein condensates and Fermionic condensates  Only observed at extremely low temperatures (within a degree or less of absolute zero). Being investigated at University of Colorado.

Substances vs mixtures  Carbon is a substance.  Water is a substance.  Air is a mixture of substances (O 2, N 2, CO 2, etc)  It is a homogenous mixture.  What is the 3 rd most abundant component of the air you breathe?  A salad is a heterogeneous mixture.

Substances vs mixtures?  You try some  Methane (natural gas)  Coffee  Copper  Salt  Dirt  Sand

What are physical separation techniques? Techniques for separating mixtures.  Evaporation—can separate DISSOLVED solids from the liquid.  Filtration—can separate UNDISSOLVED solids from the liquid.  Decanting—can separate a dense solid from the liquid (because the solid is on the bottom and you can pour off the liquid).  Distillation—can separate a mixture of liquids by boiling them and condensing the vapors (check out the distillation apparatus at the bottom of pg 40).

A physical separation technique sometimes tested on the SOL.  Chromatography  Can be used to separate a mixture of solids dissolved in a liquid.  Ink  Natural dyes  Not in Chap 2, but you better know it!!

Substances: Elements  Elements are on the Periodic Table. 90 occur naturally (1-92 except for 43 Tc and 61 Pm). 118 elements exist (but 113 Uut, 115 Uup, 117 Uus, 118 Uuo have not been named yet).  Elements 93 and higher are man made (most of them by Dr. Glenn Seaborg and his team at U. Berkeley)  119 (Uue) and 120 (Ubn) are currently being worked on but have not been synthesized as of yet.   Do any still “undiscovered” elements exist anywhere in the Universe?

Substances: Compounds  Compounds are pure substances too. There are literally millions of chemical compounds. Some common compounds are:  Salt (sodium chloride or NaCl)  Sugar (sucrose or C 12 H 22 O 11 )  Baking Soda (sodium bicarbonate or NaHCO 3 )  Sand (silicon dioxide or SiO 2 )  Rubbing Alcohol (isopropanol or C 3 H 7 OH)  Carbon dioxide (CO 2 )  Ammonia (NH 3 )  Methane (CH 4 )

Distinguishing between: Elements, Compounds, and Mixtures?  How can you tell if it’s an element or a compound or mixture?  An element cannot be broken down into anything simpler.  A compound can be separated into smaller elements.  But, you must use a chemical reaction to break down a compound, because the elements in a compound are bonded together.  A mixture can be separated using physical separation techniques.  Check out the cool flowchart at the bottom of page 44.

Ionic Compounds vs Molecular Compounds  There are 2 types of compounds  Ionic compounds have ionic bonds and are composed of positive and negative ions.  Ions are formed when atoms lose or gain electrons.  Molecular compounds have covalent bonds.  Electrons are shared between atoms. There are no ions or charges.  We will study this more in Chapter 9.

Chemical Reactions  Reactants  Products  You need to start with 1 or more reactants and You will produce 1 or more products  How many you need and how much you produce is characteristic of the specific reaction.  We will study 5 major types of reactions starting in Chapter 11.  Chemical reactions are PERMANENT and NOT reversible.

That’s Chemistry…  That’s really all chemistry is…  Atoms either take electrons from other atoms or  Atoms lose electrons to other atoms or  Atoms share electrons with other atoms  Bonds are broken during that process and new bonds are formed.  Chemistry is the interaction of my electrons with your electrons to form a bond. Electrons are involved, not the protons or neutrons.

The End