1. Chemical Energy Fuel for Life

2. What is Chemical Energy? Chemical energyis the energy that is stored in the chemical composition of matter.Chemical energy is the energy that is stored in the chemical composition of matter. An example is the energy used by cells in your body come from the chemical energy in the food you eat.An example is the energy used by cells in your body come from the chemical energy in the food you eat. –Energy is released as the chemical compounds are broken apart. Chemical Energy Compounds E E E

3. What is a Chemical Element? chemical elementA chemical element is the simplest form of a substance (matter). chemical element –If a chemical element is broken down it becomes protons, neutrons and electrons (an atom). Chemical elementsChemical elements make up all the things in the physical world around us. Chemical elementsChemical elements are listed in the Periodic Table of the Elements Chemical elements moleculescompounds.Chemical elements combine to form molecules and compounds.

5. What is an Atom? Atoms are collections of tiny bits of electricity, which we call protons, neutrons and electrons. When atoms come together to form larger clumps they are known as molecules. A molecule is a group of two or more atoms that stick together. Example: O 2, which is an oxygen molecule made from two atoms of oxygen.

6. What is a Chemical Compound? chemical compoundA chemical compound is the combination of one or more elements. –Example: H 2 O, which is water made from two atoms of hydrogen and one atom of oxygen. –Chemical compounds –Chemical compounds can not easily be separated.

8. Mixtures and Solutions mixture not chemically combinedA mixture is the combination of substances that are not chemically combined. mixture –A mixture can easily be separated (taken apart) using physical means. –Example: Sand and iron mixture. solution solutionmixtureA solution is the combination of substances in liquid form. A solution is like a liquid mixture. –Solutions –Solutions are not chemically combined so they can easily be separated. –Example: Salt dissolved in water. SolutionsSolutions can be acidic, or basic, or neutral. This characteristic of solutions is called pH.

9. What is pH? Every liquid you see will probably have either acidic or basic traits. Scientists use something called the pH scale to measure how acidic or basic a liquid is. pHpH stands for potential Hydrogen. pH0 to 14.The pH of solutions are measured on a scale of 0 to 14. 0 being the most acidic 14 being the most basic A value of 7 is considered neutral and is neither acidic or basic. Examples: pH stomach acid = pH of 2.5 distilled water= pH of 7 pH Soda ash = pH of 11

10. pH Scale Distilled Water

11. What is a Physical Change? A physical change is a change in a substance where nothing new is created, (it does not change the chemical make up of the substance).A physical change is a change in a substance where nothing new is created, (it does not change the chemical make up of the substance). –Example: Ice melts to water (both are still H 2 O). –Physical changes are usually changes in phase, or state of matter. Solid Liquid The way the water looks (state of matter) is changing, but it is still water! The way something looks.

12. What is a Chemical Change? chemical changeA chemical change is a ….. change that does create something new, (a new chemical make up results). –Example: When iron rusts. The iron (Fe) becomes iron-oxide (Fe 2 O 3 ). –Chemical changes –Chemical changes occur when elements recombine with other elements, or in different combinations. –Chemical changes –Chemical changes occur during chemical reactions.

13. Exothermic vs Endothermic Chemical reactions exothermic endothermicChemical reactions often involve heat and can be either exothermic or endothermic. Exothermicchemical reactions give off heat. (feel hot)Exothermic chemical reactions give off heat. (feel hot) Endothermicchemical reactions take in heat. (feel cool)Endothermic chemical reactions take in heat. (feel cool) EXIT In