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Parts of the Atom

Chemical Reaction Basics

What part of the atoms are affected? Electrons (valence electrons) are

affected in reactions because they decide how reactive is the atom.

An atom with one valence electron is more reactive than an atom with seven valence electrons (Figure)

Eight is the most valence electrons in an atom.

▪ These atoms are not reactive. Electrons are lost or gained in

chemical reactions. ▪ Oxidized: Atom loses electrons▪ Reduced: Atom gains electrons

Gray atom has 1 valence electronGreen atom has 7 valence electrons

Figure: Valence Electrons

http://www.visionlearning.com/library/module_viewer.php?mid=54Volume Library 1 Chapter 7 page 17 Oxidation-reduction reactions

Events during Chemical Rx

Chemical Reaction Basics

What is happening during a chemical reaction? Bonds between atoms or molecules have interactions among their

electrons breaking and/or forming new bonds.http://wiki.answers.com/Q/What_happens_when_a_chemical_reaction_occurs

Reactants & Products Application of Law of Conservation of Mass

Five Signs of a Chemical Rx

Description

Reactants which are the substances that go into the reaction come out as final substances called products

No matter what you do to the substance in chemical reactions it will still have the same mass.Actually law: Matter cannot be created nor destroyed only rearranged.

Five signs: Change of color Formation of gas Formation of precipitate

(solid separates for a solution)

Change of temperature Energy produced

Referencehttp://www.nelsonthornes.com/secondary/science/scinet/scinet/reaction/change/reactant.htm

http://en.wikipedia.org/wiki/Conservation_of_mass

http://wiki.answers.com/Q/What_are_the_5_signs_of_a_chemical_reaction

Role of Energy in Chemical Rx Forms of Energy

Potential Energy– substances have a energy due to electrons and bonds. This is the energy that bonds already have to start with for a reaction. Activation Energy– threshold energy needed to initiate a chemical Rx or energy requirement to have a chemical reactions. This is the hump

need to get over. (On next slide) Types of Energy Reactions (Table)

Exothermic Rx Endothermic Rx

DescriptionChemical reactions that release energy as part of their product

Chemical reactions that absorb energy to form the product

Basic Concept A + B AB + energy A + B + energy AB

ExampleCombustion of methane CH4 + 2O2 CO2 + 2H2O

Sports “Cold pack”2NH4NO3(5) + H2O(1) + heat NH4

+(aq) + NO3–(aq)

Graphic

1.http://www.kentchemistry.com/links/Kinetics/PEDiagrams.htm 2. http://genchem.chem.wisc.edu/demonstrations/Images/06thermo/methanebubbles.jpg 3. http://dopamine.chem.umn.edu/chempedia/index.php/Cold_Packs/Hot_Packs

Exothermic reaction Graphic illustrates that a

chemical reaction (x-axis) occurs when a threshold energy is achieved (“activation energy”) and a product is formed that generates heat (ΔH along y-axis)

Endothermic reaction Figure depicts much energy is

needed (y-axis) to “activate” the reaction (x-axis)

Products of this reaction make surrounding area colder due to higher energy needs to activate the reaction

http://www.kentchemistry.com/links/Kinetics/PEDiagrams.htm

Types of Chemical ReactionsSynthesis Decomposition Combustion Single

ReplacementDouble

Replacement

Description Two substances combine to make a single product

One substance is broken down into two substances

Oxygen is a reactant and products include carbon dioxide & water

One element replaces another as part of a compound

Two compounds “switch partners”

Basic Concept

A + B AB AB A + B CxHy + O2 CO2 + H20

A + BC AB + C AB + YZ AY + BZ

Example Iron and sulfur yields iron (II) sulfide

http://farm3.static.flickr.com/2110/1508159256_cde784b80b.jpg?v=0

Electrolysis of water to make oxygen and hydrogen gas

http://img.sparknotes.com/figures/0/02480ae8fc1a41b131a3fdb5a698e9a3/lyticcell.gif

Burning of naphthalene

http://www.separationsnow.com/FCKeditor/UserFiles/Image/sepNOW_ezines_2006/0601_sfcdetector1.jpg

Magnesium replaces hydrogen in water to yield magnesium hydroxide and hydrogen gas

http://chem200.tripod.com/flame2.gif

Lead (II) nitrate with potassium iodide forms lead (II) iodide and potassium nitrate

http://www.nitrogenorder.org/experiment/dblreplace.shtml

Chemical Formula

8 Fe + S8 8 FeS 2 H2O 2 H2 + O2 C10H8 + 12 O2 10 CO2 + 4 H20

Mg + 2 H20 Mg(OH) 2 + H2

Pb(NO3)2 + 2 KI PbI2 + 2 KNO3

http://misterguch.brinkster.net/6typesofchemicalrxn.htmlVideo on Chemical Reactions

Bibliography

Parts of the Atom http://www.visionlearning.com/library/module_viewer.php?mid=54 Volume Library 1 Chapter 7 page 17 Oxidation-reduction reactions

Events during chemical reaction wiki.answers.com/Q/What_happens_when_a_chemical_reaction_occurs http://www.nelsonthornes.com/secondary/science/scinet/scinet/reaction/change/reactant.htm http://en.wikipedia.org/wiki/Conservation_of_mass http://wiki.answers.com/Q/What_are_the_5_signs_of_a_chemical_reaction

Role of Energy in Chemical Reactions http://www.kentchemistry.com/links/Kinetics/PEDiagrams.htm http://genchem.chem.wisc.edu/demonstrations/Images/06thermo/methanebubbles.jpg http://dopamine.chem.umn.edu/chempedia/index.php/Cold_Packs/Hot_Packs

Energy and Chemical Reactions http://www.kentchemistry.com/links/Kinetics/PEDiagrams.htm

Types of Chemical Reactions http://misterguch.brinkster.net/6typesofchemicalrxn.html