CHEMISTRY NOTES - MATTER • Matter – anything that has mass and volume. • Matter is made up of tiny particles called atoms and molecules. • Phases of matter: solid, liquid, gas. Video • Heat is the cause of phase changes. More heat means faster moving particles, less attraction between particles, and more space between particles. HEAT
Phase Changes • Melting: solid becomes a liquid ( 0 ºC for water ) • Freezing: liquid becomes a solid ( 0 ºC for water ) • Boiling: liquid becomes a gas ( 100 ºC for water ) • Condensation: gas becomes a liquid ( 100 ºC for water )
Physical Change-a change in size, shape or phase of a substance. - Examples: crumpled paper, broken glass, melting, freezing, boiling • Chemical Change - a NEW substance is formed, with NEW properties. Cannot be physically separated. - How can you tell? 1) Temperature change 3) Gas formation 2) Color change 4) 2 liquids form a solid
Element - the simplest form of matter. ~ 110 known elements in the universe. • Atom - a single particle of an element. - example: 1 atom of Sodium (Na)
AMolecule is two or more atoms combined. A single particle of one compound. - Example: a water molecule is two Hydrogen atoms and one Oxygen atom. • A Compound is two or more elements that can’t be physically separated, making a certain type of molecule. - Examples: Salt, Water, carbon dioxide • A Mixture is two or more substances that can be separated, and do not form a new compound. - Examples: sand + gravel, oil + water, salt + water
Chemical Formula – a shorthand way to show the number and type of atoms in a substance. - examples: H2O O2 H2SO4 • Chemical Equation - a summary of a chemical change (reaction). * Some reactions require energy 6CO2 + 6H2O6O2 + C6H12O6 * Some reactions release energy 6O2 + C6H12O66CO2 + 6H2O + energy • The Law of Conservation of Mass states that matter can never be created or destroyed. • This can be proven by counting up the number of atoms of each element on both sides of the equation. The numbers will be equal. energy
Acids and Bases • Acid- any compound that produces hydrogen ions (H+) in water. The more H+ ions produced, the stronger the acid. • Base – Any compound that produces hydroxide ions (OH-) in water. The more OH- ions produced, the stronger the base. • An ion is simply an atom with a positive or negative charge. • The pH scaletells how acidic or basic a substance is. · measures H+ concentration on a scale of 0 to 14 · pH of less than 7 is acidic, lower pH = more acidic · pH of more than 7 is basic, higher pH = more basic · pH of 7 is neutral, pH of water = 7 • Litmus paper is an indicator, a substance that changes color when it comes in contact with an acid or base.
Structure of an ATOM Nucleus - the center of the atom Proton - positively charged (+) particle in the nucleus. Neutron - particle in the nucleus with no charge. Electron - negatively charged particle (-) outside of the nucleus. http://www.colorado.edu/physics/2000/applets/a2.html
- The Atomic Number is the number of protons (electrons usually the same) - The Atomic Mass is protons plus neutrons - To find the number of Neutrons… Atomic Mass – Atomic Number = Neutrons Element SymbolAtomic #Atomic MassPE N Oxygen O 8 16 8 8 8 Iron Fe 26 56 26 26 30
CHEMISTRY NOTES – ENERGY • All Matter has energy • Energy has many different forms • Kinetic energy (motion) Potential energy (stored) - Mechanical - Mechanical - Electrical - Electrical - Heat - Gravitational - Light - Chemical - Sound
Mechanical energy is the energy of a moving object, caused by a force. Ex: engines, a person running, throwing a ball • Electrical energy is the flow of electrons toward a positive charge. Needs a conductor like metal. Ex: extension cord, power line • Heat energy is the movement of the atoms/molecules of a substance. Ex: boiling water • Light energy is the movement light rays. Ex: sunlight, lamp • Sound energy is carried by sound waves. Ex: any noise
Chemical energy is stored in the chemical bonds of atoms and molecules. Ex: Batteries, gasoline, food Gravitational energy is stored in objects because of their position. Ex: a leaf on a tree The Law of Conservation of Energy states that energy is never created or destroyed, it simply changes form. - Example: a light bulb changes electrical energy to light and heat energy.
Flashlight Energy Transformation: When a flashlight is turned on, energy changes from potential-chemical energy (battery), to electrical energy (circuit), to light and heat energy (bulb). Flashlight Energy Transfer: When a flashlight is turned on, energy moves from the battery to the circuit wires, to the bulb, and finally to the environment.