Physical Science Second Semester Summary---Ms. Arthur Periods 2, 4, 5

Transcription

1 Matter I. Matter Physical Science Second Semester Summary---Ms. Arthur Periods 2, 4, 5 A. is anything that has mass and takes up space. B. is made up of tiny particles called atoms and molecules that are always in motion. II. Properties of Matter A. Physical Property 1. Is used to identify matter or describe matter 2. Can be observed or measured without changing the identity of matter 3. Examples= color, mass, odor, volume, thermal conductivity, state, density, solubility, ductility, malleability, shape, and size. a. Density= Mass divided by Volume; or the amount of matter in a fixed amount of space b. Density Column Least dense Most dense c. Mass vs. Weight Mass = amount of matter in an object Is always the same SI/Metric Unit= gram Weight=amount of gravitational force acting on an object Changes depending on where it is in the universe SI/Metric Unit = Newton B. Chemical Property 1. Describes matter based its ability to change into new matter that has different properties. 2. Examples= flammability (burning), reactivity with oxygen C. Characteristic Property is a physical or chemical property that is unique to a particular substance. It can be used to identify the substance. Examples are density, reactivity, magnetism, solubility, flammability/heating; melting point, and boiling point. III. Law of Conservation of Mass A. Matter cannot be created or destroyed B. Mass of reactants = mass of products C. Balancing Chemical Equations. Example: _2_H 2 + O 2 2 (H 2 O 1 ) IV. Physical vs. Chemical Changes Physical Changes Do not form new substances Chemical Changes Form new substances with different properties; Hard to reverse

2 Affect one or more physical properties One or more substances are changed Examples: Change in shape, dissolving, freezing, melting Signs: change in shape, size Examples: Digest food, baking, burning, and rust. Signs: change in color, fizzing, odor, light produced, change in acidity or alkalinity, increase in heat V. Measuring Matter Dimension SI/Metric Units Tools Length Meter (m) Metric ruler or meterstick Mass Gram (g) Triple-beam balance Volume Liter (L) Graduated cylinder (liquid, irregular solid) Metric ruler or meterstick (regular-shaped solids) Weight Newton (N) Spring scale Density (of a liquid or an irregular solid) g/ml or g/cm 3 Triple-beam balance and graduated cylinder VI. States of Matter Examples Solids Liquids Gases Ice; Anything made of glass, Liquid water, honey, juice, Steam, water vapor, oxygen, plastic, paper, wood vinegar hydrogen, helium, carbon dioxide Shape Definite (keeps its shape) Indefinite (changes shape; takes the shape of its container) Volume Definite volume (keeps its Definite volume original volume as you change containers) Indefinite Indefinite (spread out ; empty space between the particles can increase) Particle Arrangement Close together, tightly packed Close together Far apart Particle Motion (Atoms and molecules are always moving.) Vibrate in place, least kinetic energy Slide past each other Move independently of each other, most kinetic energy VII. Physical Changes of State of Matter Melting Freezing Evaporation Condensation Sublimation Solid to liquid Liquid to solid Liquid to gas Gas to liquid Solid to Gas Energy is Added Removed/Rele Added Removed/Released Added ased Endotherm Endothermic Exothermic Endothermic Exothermic Endothermic ic/exother mic Example(s) Ice melting, gallium melting in hands Water becomes ice Sweat/perspirati on Dew or drops of water on a glass Dry ice at room temperature

3 VIII. Phase Change Graph for Water/Physical Changes Solid=ice Liquid = water Gas= water vapor IX. Water- behaves differently from most other liquids. A. Most liquids contract and get smaller as they are cooled down. Water contracts at first but once it is cold enough it expands to form a solid. B. Solid water (ice) is less dense than liquid water which makes ice float. X. Atomic Structure A. Parts of an atom Subatomic Particles Electron Proton Neutron Charge Negative Positive none Location Electron Cloud Nucleus Nucleus B. Ions 1. Positive when neutral atoms lose electrons(s). 2. Negative when neutral atoms gain electron(s). C. Isotopes-= atoms of the same element with different number of neutrons, different mass number, same number of protons, same number of electrons, overall charge is zero, XI. Periodic Table of Elements A. Dmitri Mendeleev developed the Periodic Table B. Is arranged into groups and periods C. Groups are in columns groups or families; and hydrogen 2. Same group= similar properties 3. Group 1=Alkali Metals= most reactive, metals

4 4. Group 2= Alkaline-earth metals= less reactive, metals, 5. Group 3-12=Transition metals= even less reactive, metals 6. Group 17= halogens= nonmetals 7. Group 18=noble gases, nonreactive, nonmetals, inert, least reactive elements D. Periods are in rows 1. 7 periods 2. Properties change from left to right. E. Common elements and their symbols: B= boron, C= carbon, Cl= chlorine H= hydrogen, N= nitrogen, Na= sodium, O= oxygen silver (Ag), gold (Au), sulfur (S) F. Chemical Formulas 1. Number of atoms in a molecule If there is more than one atom of a type in the molecule, the formula shows it by a small number after the symbol. For example, water is H 2 O, which means there are 2 atoms of hydrogen and one atom of oxygen in the molecule. Carbon dioxide is CO 2, which means there are one atom of carbon and two atoms of oxygen in the molecule. 2. Number of molecules To show the number of molecules, a full sized number is located in front of the molecule. For example 4 molecules of carbon dioxide would be designated as: 4CO 2. This means there are a total of 4 C atoms and 8 O atoms in the combination. A way to remember this--taken from Algebra--is to think of it as 4 x (CO 2 ). G. Elements can be classified as Metals Metalloids Nonmetals Shiny, ductile, malleable, good conductors of electric current and thermal energy On both sides of the zigzag line of the Periodic Table; semiconductors; have some properties of metals and nonmetals Not malleable, not shiny, poor conductors of electric current and thermal energy XII. All matter can be describes as either a pure substance or a mixture. A. Pure substances= elements and compounds= cannot be separated into more than substance by physical means. Elements Compounds Cannot be broken down by chemical means Can be broken down by chemical means One kind of atom Different kinds of atoms bonded together Examples Hydrogen (H), Carbon (C), Oxygen (O), Nitrogen (N), Sulfur (S) Glucose, salt, lye, vinegar, bleach, baking soda B. Mixtures= 2 or more kinds of matter not chemically combined= can be homogeneous or heterogeneous Homogeneous Heterogeneous Composition uniform Non-uniform

5 Examples Solutions= solute dissolved in a solvent Sand and water; milk States Gas in gas Solution Example Air (oxygen in nitrogen) Gas in liquid Liquid in liquid Solid in liquid (Factors that speed up dissolving are: heating, stirring, increase surface area, increase pressure) Solid in solid Soda (carbon dioxide in water) Antifreeze (alcohol in water) Salt water (salt in water) Brass (zinc in copper) C. Separating Mixtures through Physical Methods 1. Filtration --separate by size, ex. sand from water 2. Distillation/Boiling separate water from solids, ex. sugar or salt from water 3. Magnet separate iron XIII. Acids and Bases/ ph Acids Sour, corrosive, poisonous Turns litmus paper red/pink Low ph Examples Citric acid, sulfuric acid, hydrochloric acid Neutralization Reaction: acid + base a salt (neutral) + water (neutral) Bases Bitter, slippery, corrosive Turns litmus paper blue High ph Soap, bleach, detergent, baking soda ph Scale 0 Hydrochloric acid 1 Stomach acid Acids (Strong acids= ph 0, 1, 2) 2 Lemon juice 3 Vinegar 4 Soda 5 Rainwater 6 Milk

6 Neutral 7 Pure water 8 Egg whites 9 Baking soda Bases (Strong bases= ph 12, 13, 14) 10 Tums antacid 11 Ammonia 12 Mineral lime - Ca(OH) 2 13 Drano 14 Sodium hydroxide Energy I. Energy= ability to do work A. All forms of energy are either potential or kinetic. B. Light= electromagnetic energy, solar energy, radiant energy C. Nuclear Energy= fission or fusion of an atom s nucleus 1. Potential Energy= energy of position a. Increase in height or change in position= increase in PE b. Examples= gravitational-=go higher, elastic=stretched rubber band, chemical=food, fossil fuels 2. Kinetic Energy= energy of motion a. Increase in mass or speed = increase in KE b. Examples= go faster or slower, heavier or lighter D. Mechanical Energy=amount of work due to PE + KE 1. Example= juggling, turbines E. Closed Systems/Law of Conservation of Energy= Energy cannot be created or destroyed. Because of this, the total amount of energy in a closed system stays the same II. F. Renewable Energy Resources= can be used over and over again; examples= solar, wind, biomass G. Nonrenewable Energy Resources= limited quantities, cannot be replaced within a person s lifespan; examples= fossil fuels (natural gas, petroleum, and coal) Heat A. Heat= energy transferred between objects at different temperatures. B. Temperature= average kinetic energy of particles in an object; how cold or hot something is. 1. Unit Conversion a. Celsius to Fahrenheit (9/5 x Celsius) + 32 b. Fahrenheit to Celsius (5/9 x (Fahrenheit -32) 2. Temperature Facts a. Water boils at 100 o C or 212 o F b. Water freezes at 0 o C or 32 o F

7 C. Heat Transfer 1. Conduction(direct contact) grabbing a hot spoon in a pot, shaking hands 2. Convection(liquids and gases) heating a pool 3. Radiation (through empty space) sun shining, roasting a marshmallow D. Heat Conductors- metals, glass because they conduct heat well. E. Heat Insulators- nonmetals, Styrofoam because they do not conduct heat well. Electricity I. Electric Current= rate at which charges pass a given point II. Electric Charges attract= + and - ; repel= - and - or + and + III. Electric Circuits Open and Closed Open Circuit (electrons are not flowing) Switch is off Or an insulator like glass, wood, plastic is used in the circuit Closed Circuit (electrons are flowing) Switch is on Conductors, like metals, keep circuits closed IV. Electrical Conductors and Insulators a. Water is comprised of two elements - hydrogen (H) and oxygen (O). Distilled water is pure and free of salts; thus it is a very poor conductor of electricity. By adding ordinary table salt (NaCl) to distilled water, it becomes an electrolyte solution, able to conduct electricity. b. Conductors are made of materials that electricity can flow through easily. These materials are made up of atoms whose electrons can move away freely. Some examples of conductors are copper, aluminum, gold, silver, people, and animals c. Insulators are materials opposite of conductors. The atoms are not easily freed and are stable, preventing or blocking the flow of electricity. Some examples of insulators are: glass, plastic, rubber, wood, and yarn V. Electric Circuits---Series and Parallel Series One loop or path Light Bulb comes off if one is removed Light bulbs are dimmer if one is added Parallel Multiple paths, loads are side by side Light bulb stays on if one is removed Light bulb stay bright if one is added VI. Short Circuit= When you replace one of the light bulbs in your circuit with a wire, there is a path in the circuit with no light bulb to slow down the moving charges. This is very dangerous because so much current will heat up the wire and could even start a fire! Short circuits can be avoided by using fuses, devices that melt if circuits are too hot.

8 VII. Resistance= opposition to the flow of electric charge A. Low resistance good conductors like copper; thick, short, cold B. High resistance--- poor conductors ( are insulators) like iron, light bulb filament; thin, long, hot VIII. Electrolyte= a solution that conducts an electric current. Electromagnetism I. Magnets and Domains A. Magnetism= is a characteristic of a substance where the force of attraction or repulsion is due to electron arrangement in atoms. B. Magnets attract iron or things made of iron C. Magnetic Force attract= North to South; repel= North to North or South to South D. Magnetic Field==the closer the lines, the stronger the magnet E. Domain== are tiny magnets in materials; their N and S poles must line up. F. Types of magnets 1. Ferromagnets (contain iron, nickel, or cobalt) 2. Electromagnets ( coil of wire around an iron core) (Note: Solenoids==only wire coil, no iron core) 3. Increase in magnetic field if increase loops of wire or increase in current. Miscellaneous I. Scientific Method(s) Definitions A. Hypothesis= educated guess B. Observation= Use 5 senses- hearing, seeing, taste, touch, smell C. Variable= any factor in an experiment that can change or vary D. Dependent variable= results, what you are measuring in an experiment E. Independent variable= what the scientist changes in an experiment II. Lab Safety Rules (See the Escobedo Safety Contract)

9