PS CH 10 matter properties and changes editedPresentation Transcript
Chapter 3: Matter—Properties and Changes Section 3.4 Types of Matter Elements & Compounds
What is matter?• Anything that has mass and takes up space• Mass is a measurement of the amount of matter in an object. It is different than weight which measures the amount of matter AND the gravitational pull on an object.
Now that you’re an expert, which of thefollowing is matter? Matter Not 1. A book Matter 2. A house 3. A thought 4. Your brain 5. Light 6. Your cell phone 7. Radio waves
There is so many different kinds of matter, that we need to organize it. Substances have a uniform and unchanging composition examples: salt, water, sugar
Chemical symbols• Make it easy to write the formulas for chemical compounds• Ex: salt water NaCl H 2O
Elements• A pure substance that cannot be broken down into simpler substances by physical or chemical means• 91 naturally occurring elements• Symbolized by one capital letter or one capital letter and 1 lower case – ex: S = sulfur – Na = sodium• In mid 1800’s, no chart for organizing the elements that were known at the time
Dmitri Mendeleev--1869-Organized the knownelements into a table ofrows and columns basedon their similarities andmasses.
Periodic table• Organized into horizontal rows called periods and vertical columns called families• Called “periodic” because properties of elements repeat as you move from period to period• Mendeleev’s table left blank spaces for elements yet to be discovered and predicted their properties
Compounds• A combination of 2 or more different elements that are combined chemically• Most of the matter in the universe are compounds• Ex: water (H2O), sugar (C12H22O11), salt (NaCl), aspirin (C9H8O4)
Compounds• Can be broken down into simpler substances by chemical means• Usually requires energy
Compounds• Properties of a compound are different from its component elements• Ex: water—liquid at room temp. Hydrogen—a colorless, tasteless gas Oxygen—a colorless, tasteless gas
Sodium chloride• As a compound, it is a white, unreactive solid that adds flavor to food• Its component elements:Chlorine—poisonous, pale,green gas Sodium—a highly reactive element that fizzes in water
States of MatterClassification based upon the following: Particle arrangement Energy of particles Distance between particlesState of matter is dependent on temperature and pressure of the surroundings
3 states of matter
States of Matter1. Solid—has a definite shape and volume exs: wood, desk, shoes, sugar -particles are tightly packed, incompressible
States of Matter2. Liquids—have a constant volume, -no definite shape -takes the shape of its container -particles are not held rigidly in place, allows material to flow
States of Matter3. Gases—have no definite shape or volume -particles are very far apart -particles are easily compressed
Section 3.3Mixtures of Matter
Mixtures• A combination of 2 or more pure substances in which each pure substance retains its individual chemical properties.
Types of Mixtures1. Heterogeneous—individual substances remain distinct
Types of Mixtures2. Homogeneous—has a constant composition throughout -called a solution
Separating Mixtures1. Physical separation: hand selection or pouring through sieves
Separating Mixtures2. Filtration—uses a porous barrier to separate a solid from a liquid
Separating Mixtures3. Distillation—based on differences in the boiling points of the substances involved
Separating Mixtures4. Crystallization—results in the formation of pure solid particles of a substance from a solution containing the dissolved substance
Separating Mixtures5. Chromatography— separating the components of a mixture based on the tendency of each to travel across the surface of another material.
Matter Pure Mixtures substancesHeterogeneous Homogeneous Mixtures Mixtures Elements Compounds Dirt, blood, Lemonade, Oxygen, gold, Salt, baking milk gasoline, steel iron soda, sugar
Section 3.1Properties of Matter
Physical Properties of Matter A characteristic that can be observed or measured without changing the composition of the sample Properties such as density, color, odor, taste, hardness, melting point, boiling point
Physical Properties of Matter: Two Types1. Extensive: dependent on the amount of substance present --length, volume2. Intensive: independent of the amount of substance present --density, melting point, boiling point --used to identify substances
Chemical Properties Ability or inability of a substance to combine with or change into one or more other substances
Physical Chemical Properties Properties• Conducts electricity • Forms dark blue• Malleable solution with• Ductile ammonia• Reddish brown • Forms green• Shiny compound when exposed to air• Density = 8.92 g/cm 3• Melting pt = 1085°C• Boiling pt = 2570°C
Classify each as a physical or chemical property:1. Iron and oxygen form rust.2. Iron is more dense than aluminum3. Magnesium burns brightly when ignited.4. Oil and water do not mix.5. Mercury melts at -39°C.
Section 3.2Changes in Matter
Physical Change• Changes in a substance’s appearance, not in composition
Types of physical changes:•Bend, grind, crumple•Split, crush, twist•Boil, freeze, melt, vaporize(changes of state or phase) (.wav)
Chemical Changes• A change in the composition of a substance• Also called a chemical change or chemical reaction• Ex: rust, corrode, tarnish, rot, burn, ferment, explode, oxidize
become sThe substancehas changed. becomes
Evidence of Chemical Change2. Energy change:absorbed or released
3. Odor changesor production 4. Gas production5. Precipitateformation
Classify each as a physical or chemical change:1. A dead fish rotting2. Dissolving salt in water3. Boiling salt water until only salt remains4. Melting steel5. Bending steel6. Cracking ice
Section 3.3 & 3.4 Laws of Matter
Law of Conservation of MassMass is neither created nor destroyed during a chemical reaction—it is conserved. (Antoine Lavoisier) Mass of reactants = Mass of products
Antoine Lavoisier—aFrench scientisto 1743-1794o Father of ModernChemistryo One of the first to usean analytical balance
When you burn a big pile of wood, why doyou only end up with a tiny pile of ashes?
In an experiment, 10.00 g of red mercury (II) oxidepowder is placed in an open flask and heated until itis converted to liquid mercury and oxygen gas. The liquid mercury has a mass of 9.26 g. What is the mass of oxygen formed in the reaction?
Practice problems—pg. 65 #6, 7, 9
Law of Definite Proportions• John Dalton• A pure substance will always have the same percent by weight• Ex: water (H2O) = 11.2 % hydrogen 88.8% oxygen
To find percent by mass:Percent by mass = mass of element x 100 mass of compound
Analysis of sugar: 20.0 g sugar 500.0 g sugarCarbon 8.44 g 42.2% Carbon 211.0 g 42.2%Hydrogen 1.30 g 6.5% Hydrogen 32.5 g 6.5%Oxygen 10.26 g 51.30% Oxygen 256.5 g 51.30%
Therefore…• Sugar always has the same proportions of ingredients• If a substance has different proportions, it is a different substance
A 78.8 g sample of an unknown compound contains12.4 g of hydrogen. What is the percent by mass of hydrogen in the compound?Percent by mass = mass of element x 100 mass of compound
Practice problems—pg. 76 #21-24
Law of Multiple Proportions• When different compounds are formed using the same elements, different masses of one element combine with the same relative mass of the other element in small, whole number ratios.