1. Name one type of chemical bond and tell me how it bonds.

2. Draw a Lewis dot diagram of an atom of Oxygen which has an atomic number of 8 (also figure out how many valence electrons it has)

3. Which of the three bonds is the weakest?

4. Which chemical bond is formed when two atoms share electrons?

5. Why is water cohesive? (why does it stick together really strongly?)

Warm UP 9/8/11

Warm up 9/9/111. What are the four types of chemical reactions? 2. Which type takes two separate molecules and

combines them together?3. Which reaction type breaks molecules down? 4. Which type of reaction needs energy in to get

the reaction started? 5. Which reaction releases energy? 6. What is a covalent bond? Ionic bond?

Three folds or sections:

• 1. The type of bond• 2. Define the bond or how it forms. • 3. Give an example of something that bonds

like this. • 4. Draw a picture of this type of bond showing

either gaining or losing electrons, sharing electorons or the charges from Hydrogen bonds.

• Chemical Reaction – a process that changes one set of chemicals into another.– Involves the breaking and

forming of new bonds. Quantity remains the same.

• 1 + 1 = 2 1 + 1 2

• If this represented a chemical reaction, then 1=reactants and 2 = product

• The reactants “react” to form the product.

Synthesis/Anabolic Reaction: when two or more atoms bond to form a more complex structure.

Example: fixing worn or damaged tissues requires a build up of smaller molecules coming together to make a larger molecule.

A + B AB

Decomposition/catabolic reaction: When a bond holding atoms together breaks and produces a simpler molecule.

Example: Is needed for foods to be digested and energy to be released for organisms to use. AB A + B

Activation Energy

• All reactions need energy to occur.• Activation Energy Activation Energy – refers to the energy

needed to get the reaction startedFor example, you must apply force when

striking a match to get the fire to start.

Activation Energy

Example: photosynthesis – reactants of water and CO2 and energy from the sun (activation energy) creates products of Glucose and O2.

Endothermic reactionsEndothermic reactions – requires energy to be – requires energy to be absorbed to complete the reaction. Therefore absorbed to complete the reaction. Therefore there will be more energy in the products than there will be more energy in the products than in the reactantsin the reactants

Activation Energy

• Example: combustion reactions of fuels. Heat releasing reactions

Exothermic reaction- Exothermic reaction- Requires energy to be Requires energy to be released to complete the reaction. Therefore, released to complete the reaction. Therefore, there will be less energy in the products than in there will be less energy in the products than in the reactants. the reactants.

Catalysts Catalyst - a substance that lowers a

chemical reactions activation energy ◦In other words, speeds up the reaction.

Enzymes

•The names of enzymes typically end in “-ase”

•For example: protease splits proteins.

•What do you think carbohydrase does?

•Also used for: synthesis of RNA and DNA.

Biological Catalysts are called Enzymes. They speed up chemical reactions in the cells.

Endothermic Reactions

• http://www.plms.issaquah.wednet.edu/teachers/abraham/PDF's/Exothermic%20and%20Endothermic%20Reaction%20Lab%202009%20_with%20data_.pdf

Endothermic and exothermic Reactions Lab

Grab a pair of safety goggles and partner or group of 3 we’re going to do a lab

Oh no I messed up! Please write this in your notes • Exothermic: the temperature increases!! This is because energy is

being released So the yeast and H202 reaction where the temp increased is considered an exothermic reaction.

• Endothermic: the temperature decreases!! So the hot tap water and Epsom salt where temperature decreased is considered an endothermic reaction. This is because the energy from the hot water is being absorbed in the reaction causing the temp to go down.

• Please fix your answer in your labs.

• Because of the confusion the only thing I will ask you to know on a quiz or test is that exothermic reaction release energy and endothermic reactions absorb energy.

Chemistry Vocabulary review

• Matter Covalent bonds• Liquid Hydrogen bonds • Solid Chemical reaction• Gas Reactants• Neutrons Products• Electrons Synthesis/Anabolic Reactions• Protons Decomposition/catabolic

reactions• Nucleus Activation Energy • Atomic number Endothermic reactions • Valance electrons Exothermic reactions • Ions Catalyst• Ionic bonds Enzymes