Energy and Reactions
matter and energy matter: anything that has mass and takes up space energy: ability to do work or cause change energy is used anytime a change in matter occurs
Nature of Energy Energy is all around you! You can hear energy as sound. You can see energy as light. And you can feel it as wind.
You use energy when you: hit a softball. lift your book bag. compress a spring.
Nature of Energy Living organisms need energy for growth and movement.
Nature of Energy Energy is involved when: a bird flies. a bomb explodes. rain falls from the sky. electricity flows in a wire.
energy Energy is the ability or the potential to make something happen (do work); that is to move or to change a condition many forms mechanical thermal electromagnetic electrical chemical
Heat Energy The internal motion of the atoms is called heat energy, because moving particles produce heat. Heat energy can be produced by friction. Heat energy causes changes in temperature and phase of any form of matter.
Chemical Energy Chemical Energy is required to bond atoms together. And when bonds are broken, energy is released.
Chemical Energy Fuel and food are forms of stored chemical energy.
Electromagnetic Energy Light is a form of electromagnetic energy. Each color of light (Roy G Bv) represents a different amount of electromagnetic energy. Electromagnetic Energy is also carried by X-rays, radio waves, and laser light.
Energy Conversion Energy can be changed from one form to another. Changes in the form of energy are called energy conversions.
Energy conversions All forms of energy can be converted into other forms. The sun’s energy through solar cells can be converted directly into electricity. Green plants convert the sun’s energy (electromagnetic) into starches and sugars (chemical energy).
changes in matter Energy is used anytime a change in matter occurs two kinds changes in matter physical changes chemical changes
physical change alters form or appearance of material, but does not change material into brand new substance examples chopping wood bending wire molding clay
chemical change produces new substances examples wood burning sour milk
Chemical reactions occur when bonds between the outermost (valence) electrons are formed or broken Chemical Reactions
Chemical reactions involve changes in matter, the making of new materials with new properties, and energy changes. Chemical Reactions
The charcoal used in a grill is basically carbon. The carbon reacts with oxygen to yield carbon dioxide. The chemical equation for this reaction, C + O 2 CO 2, contains the same information as a sentence but has quantitative meaning as well.
Chemical Reaction Equations H 2 + Cl 2 --> 2 HCl Symbols represent elements, formulas describe compounds, chemical equations describe a chemical reaction
Chemical Reaction Equations H 2 + Cl 2 --> 2 HCl
– Chemical equations show what enters the reaction - reactants (the molecules shown on the left of the arrow) and what comes out of the reaction - products (the molecules shown on the right of the arrow). Chemical Reaction Equations
H 2 + Cl 2 --> 2 HCl reactants --> products
Subscripts vs. Coefficients The subscripts tell you how many atoms of a particular element are in a compound. The coefficient tells you about the quantity, or number, of molecules of the compound.
4 Al + 3 O 2 ---> 2 Al 2 O 3 This equation means 4 Al atoms + 3 O 2 molecules ---produces---> ---produces---> 2 molecules of Al 2 O 3 2 molecules of Al 2 O 3 Chemical Equations
Endergonic & Exergonic reactions Endergonic Energy IN Putting together bonds Exergonic Energy OUT Breaking bonds apart
Endergonic or Exergonic reactions? What types of energy?
Endergonic & Exergonic reactions vs. Endothermic & Exothermic reactions Therm – heat Ergon – any type of energy so Endothermic reaction is a type of endergonic reaction
Endergonic reaction – any type of energy taken in Endothermic reaction – only heat energy taken in Exergonic reaction – any type of energy given off Exothermic reaction – only heat energy given off