LESSON 1: DESCRIBING MATTER pg.5. Chemistry = Is the study of matter & how matter changes. Liquid/Solid/Gas

Transcription

1 Chemistry..CHAPTER 1: INTRO TO MATTER LESSON 1: DESCRIBING MATTER pg.5 Chemistry = Is the study of matter & how matter changes A. Matter = anything that has mass & takes up space à You, air, plastic, metal, wood, glass, paper & cloth are all made of matter àmatter Can Be: Hard/ Soft, Hot/Cold, Liquid/Solid/Gas B. Pure Substance = SINGLE TYPE of matter.has a specific make-up/composition 1. EXAMPLE: ( NaCl )Table salt (it s the same even if it is in seawater or a salt mine).. its still salt 2. EXAMPLE: (H 2 O) Pure water (whether from glacier or geyser).. its still water

2 PHYSICAL PROPERTY à properties that describe a change in how it looks but does NOT change into anything new. CHEMICAL PROPERTY à properties that describe how a substance changes into a completely NEW substance EXAMPLES: Freezing Melting Boiling EXAMPLES: Rusting Burning Reactivity (explosive) LESSON 2: CLASSIFYING MATTER.. Pg 8 What Is Matter Made Of? è 450 BC Empedocles said all matter is made of a combo of air, earth, fire & water (Believed for almost 2000 years!) ATOMS à The base particle from which all elements are made ** ATOMS COMBINE TO MAKE ELEMENTS ELEMENT à substance that CANNOT be broken down into any other substance 1. Elements are identified by their physical & chemical properties a. Represented by one or two letter symbols b. ANY SINGLE BOX ON THE PERIODIC TABLE IS AN ELEMENT!!!! COMPOUND à When 2 or more elements combine they make a compound 1. Chemical Formula = shows the elements in the compound and ratio of elements present. a. Example: CO 2 1 carbon atom + 2 oxygen atoms = carbon dioxide

3 2. Molecule= group of 2 or more atoms held together by a chemical bond a. Chemical Bond = what is made when atoms combine b. Molecules are bigger than atoms c. (EXAMPLE: Oxygen atom + Oxygen atom = Oxygen Molecule, ( O 2 ) H 2 ( H & H) & O 2 ( O & O ) are molecules, but can NOT be compounds because they are only made of a SINGLE element. ALL COMPOUNDS ARE MOLECULES BUT NOT ALL MOLECULES ARE COMPOUNDS! MIXTURES à2 or more substances that are together in the same place, but their atoms are NOT chemically bonded * Each substance in a mixture KEEPS its own properties Heterogeneous Mixture - can usually see different parts & they are easily separated out Homogeneous Mixture - EVENLY mixed parts... really hard to see individual parts SOLUTION= Is a type of homogenous mixture EXAMPLES: - Pizza - Raisin Bran cereal 1. Filter it 2. Use Magnets 3. Distill it 4. Evaporate it EXAMPLES: - Air - Chocolate Milk WAYS TO SEPARATE MIXTURES:

4 PHYSICAL CHANGE à change which alters the form or appearance of matter but does NOT turn any substance in the matter into a different substance. IT IS STILL THE SAME SUBSTANCE AFTER THE CHANGE * Changes between solids/liquids/gases * Change that only alters the shape or form of matter * Crushing * Folding * Freezing * Melting * Boiling * Tearing * Dissolving CHEMICAL CHANGE à change in matter that makes one or more NEW substances * Heat, light or electrical energy is often given off or absorbed. A COMPLETELY DIFFERENT SUBSTANCE IS CREATED!! Look for these common terms: reacts, corrodes, bubbles, changes color, produces, decomposes, burning, digesting, etc. LESSON 4: CHANGES IN MATTER Pg 20 Law of Conservation of Mass = matter is not created OR destroyed in a chemical change, it is only transformed. à Antoine Lavoisier (1770s) he measured mass before & after chemical change & found that no mass was lost or gained. EVERY chemical & physical change in matter includes a change in energy.

5 TEMPERATURE à measure of how hot or cold something is. * Faster particles move = Greater Energy (Higher Temps) * Slower particles move= Lower Energy (Low Temps) * At room temp particles in a gas travel 500 meters per SECOND!! THERMAL ENERGY à total energy of the motion of all of the particles in an object. ** You experience TE when you describe how hot or cold something is *** Thermal Energy flows from hotter to cooler matter ( Ex: That s why ice cream melts on a hot summer day) THERMAL ENERGY CAN BE RELEASED OR ABSORBED WHEN MATTER CHANGES Endothermic Change = energy is absorbed (Think.. Endo = Enter) heat is absorbed & cools the immediate surroundings Exothermic Change = energy is released (Think Exo= Exit) temp rises in the immediate surrounding EXOTHERMIC Freezing ice cubes Rusting iron Burning sugar Candle flame Chemical Energy = energy stored btwn bonds of atoms ENDOTHERMIC a. Chemical energy is also stored in foods, fuels & cells of your body. b. Burning fuels transforms chemical energy & releases some of its thermal energy c. Riding bike up a hill chemical energy transforms foods you ate to energy of motion Melting ice cubes Cooking an egg Baking Bread Boiling water (LiquidàGas)

6 CHAPTER 2 LESSON 1: STATES OF MATTER Pg 40 Solid = has definite shape & volume 1. Particles are closely packed 2. Particles stay in one position 3. Types of Solids: a. Crystalline solid = solids that are made of crystals (Ex: Salt, Sugar, Snow) i. Particles form regular repeating pattern ii. Melts at a specific temp b. Amorphous solid = particles are NOT arranged in a regular pattern i. Does NOT melt at a specific temp ii. Ex: Glass, Plastics, Rubber Liquid = has definite volume, but NO shape of its own 1. Particles are packed closely together 2. Particles flow into different positions so they are called fluids. 3. Properties of Liquids: a. Surface tension = pull among molecules that brings surface molecules closer together i. Ex: Beading of water on surfaces, bugs walking on water, needle floating on water

7 b. Viscosity = liquids resistance to flowing i. Viscosity depends on size & shape of its particles ii. High Viscosity= Flow SLOWLY (EX: honey) iii. Low Viscosity = Flow FAST (Ex: Vinegar) Gas = NO definite shape OR volume 1. Particles move and fill all available spaces 2. When working with gas it is important to know volume, temp & pressure: a. Volume- amount of space matter fills i. Measured in cm 3, m 3, ml & L ii. VOLUME OF A GAS IS SAME AS VOLUME OF A CONTAINER! b. Pressure= force pushing on a surface divided by area of surface ( PRESSURE = Force / Area) i. Measured in kpa (kilopascals) or Pa (pascals) ii. If concentration of gas particles Increase.. Pressure Increases iii. If concentration of gas particle Decrease Pressure Decreases c. Temperature- measure of average energy of particles moving

8 CHAPTER 2 LESSON 2: CHANGES OF STATE Pg 48 Melting = change of state from a solid to a liquid 1. Melting Point= specific temp when melting occurs ENERGY IS GAINED.. THERMAL ENERGY a. Melting Points (MP) help scientists identify unknown materials b. H 2 O s melting point is 0 C c. At the melting point the particles vibrate fast enough to break free of their fixed positions Freezing = going from liquid to solid 1. Freezing Point is when particles are moving SLOWLY enough that they begin to take on fixed positions. ENERGY IS LOST Vaporization = change from liquid to gas 1. When particles in liquid gain enough energy to move independently 2. Types of Vaporization: a. Evaporation = vaporization ONLY on SURFACE of any liquid b. Boiling= vaporization BELOW AND ON SURFACE of a liquid i. Boiling Point (BP) = temp at which liquid boils ii. BP s help identify substances

9 Condensation = REVERSE of vaporization ( Gas à Liquid) 1. Happens when particles in a gas LOSE enough thermal energy to form a liquid 2. Causes clouds.. then falls to earth as rain Sublimation = when surface particles of a solid gain enough energy that they form a gas 1. Particles SKIP liquid state go from Solid & jump to a gas. 2. Example: Dry Ice