1.1 The Puzzle of Matter What is Chemistry? What is Matter?

What is Chemistry? CHEMISTRY- Is the study of the structure and properties of matter It’s composition, or “what it’s made of” The characteristics and behavior; What it looks like, any changes it goes through Ex: color, odor, shape, hardness, texture… Has Mass and Volume (you can see and touch it)

What is Matter? Matter is anything that takes up space (has volume) AND has mass. Amount of space an object takes up. Amount of “stuff” (matter) in an object

Examples of Matter

What is NOT matter? Electricity Thought Heat Fire Light

Classification of Matter Chemical methods

Matter can be classified into 2 main categories MIXTURES A combination of two or more substances in which the basic identity of each substance is not changed. CAN be separated by physical means Example: lemonade = lemon juice, water and sugar PURE SUBSTANCES Matter with the same composition and properties. Can’t be separated by physical means Example: pure gold, pure silver, pure oxygen.

Mixtures Pure Substances

MixturesPure Substances

What’s a Pure Substance and What’s a Mixture? Pure Substance an element (hydrogen) Pure Substance a compound (water) Mixture (hydrogen and oxygen) Mixture (hydrogen and oxygen) Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 68 hydrogen atoms hydrogen atoms oxygen atoms

What’s a Pure Substance and What’s a Mixture? A pure substance is matter with the same fixed composition and properties. Any sample of pure matter is a substance. A mixture is a combination of two or more substances in which the basic identity of each substance is not changed.

Mixtures can be classified into two categories Chemical methods

Mixtures can be classified into two categories Heterogeneous Mixtures A mixture that does not have a uniform composition You can see the different parts Ex: oil and water Homogeneous Mixtures A mixture that has a uniform composition You CAN’T see the different parts Ex: sugar and water DifferentSameOrigin

HeterogeneousHomogeneous

What’s a Heterogeneous Mixture? What’s a Homogeneous Mixture?

Pure Substances can be classified into two categories! Chemical methods

Pure Substances can be classified into two categories also! ELEMENTS Simplest form of matter Made of all one type of atom. Are ALL found on the periodic table ex: gold, diamond (carbon), copper COMPOUNDS Combination of two or more different elements joined together in a fixed proportion ex: water, table salt, sugar, carbon dioxide

COMPOUNDSELEMENTS

What’s an element and What’s a compound?

Classify each picture as an element, compound, heterogeneous mixture, or homogeneous mixture.

Properties of Matter Physical Properties Definition: A characteristic of a substance that can be observed or measured WITHOUT changing the identity (or composition) of the substance EX: shape, phase, color, odor, hardness, luster, texture, melting point, boiling point, freezing point, magnetism, density, conductivity… Chemical Properties Definition: A characteristic of a substance that can only be observed by changing the identity (or composition) of the substance. EX: the way something can burn, rust, ferment, corrode, tarnish, oxidize, decompose

Density Density is a physical property – we can observe it without changing the matter (we can calculate density). Density is also called a “Derived Unit” because we do math to calculate it.

Copper — Physical Properties reddish brown, metallic luster (shiny) it is malleable (easily formed into thin sheets) and ductile (easily drawn into wires) good conductor of heat and electricity can be mixed with zinc to form brass or with tin to form bronze density = 8.95 g/cm 3 melting point = 1083°C boiling point = 2570°C

Copper — Chemical Properties slowly forms a green carbonate in moist air reacts with nitric acid and sulfuric acid forms a deep blue solution in aqueous ammonia

What are Physical Properties and What are Chemical Properties? Examples: –melting point –flammable –density –magnetic –tarnishes in air Physical Chemical Physical Chemical

27 Chumbler - Properties of Matter Phases of Matter (Physical Properties of Matter) The Four Phases of Matter The Four Phases of Matter SolidSolid LiquidLiquid GasGas PlasmaPlasma

Solids  Particles of solids are tightly packed, vibrating about a fixed position.  Solids have a definite shape and a definite volume.

Liquids Particles of liquids are tightly packed, but are far enough apart to slide over one another.Particles of liquids are tightly packed, but are far enough apart to slide over one another. Liquids have an indefinite shape (they take the shape of their container) and a definite volume.Liquids have an indefinite shape (they take the shape of their container) and a definite volume.

31 Chumbler - Properties of Matter Gases PPPParticles of gases are very far apart and move freely and faster than liquids. GGGGases have an indefinite shape and an indefinite volume.

32 Plasma The negatively charged electrons (yellow) are freely streaming through the positively charged ions (blue ). plasma is an ionized gas. – the particles move SO fast they smash into each other and lose electrons!plasma is an ionized gas. – the particles move SO fast they smash into each other and lose electrons! A plasma is a very good conductor of electricity and is affected by magnetic fields.A plasma is a very good conductor of electricity and is affected by magnetic fields. Plasma, like gases have an indefinite shape and an indefinite volume.Plasma, like gases have an indefinite shape and an indefinite volume.

Physical and Chemical Changes Chemical Change Definition- when a material undergoes a change so that one or more “NEW” substances with different characteristics forms. -atoms get rearranged Example-rusting, burning, digestion, decomposition, cooking Physical Change Definition-a change where the composition of the material is NOT changed. -Nothing new is made Example- tearing, ripping, grinding, cutting, dissolving

Physical and Chemical Changes Chemical Change Rule of thumb: -you can’t usually “un-do” a chemical change -you make something new Often chemical changes: –make a gas or odor –involve a color change –form a solid (called a precipitate) –involve energy being given off (feels hot) or taken in (feels cold) Physical Change Rule of thumb -you can usually “un-do” a physical change -you have the same “stuff” before and after (you don’t make something new) -some physical changes (state changes) will involve changes in energy ex: melting/freezing etc…

Chemical Changes

Physical Changes

What are Physical Changes and What are Chemical Changes?

Law of Conservation of Mass Definition- During a chemical reaction, matter is not created or destroyed. Mass is conserved What does it mean? You will have the same amount (mass) of matter at the end of a reaction as at the beginning.

Before Chemical Reaction After Chemical Reaction What is the Mass before and after the reaction? Two chemicals are separate Two chemicals get mixed New Substance (and precipitate) gets formed The mass is the same before AND after because of the LAW OF CONSERVATION OF MASS!!

Is the Mass on each side of the reaction the same? 18 grams of water16 grams of oxygen2 grams of hydrogen 18 total grams

Count the Atoms on each side. Are they equal? 2 Oxygen atoms4 Hydrogen atoms +2 Hydrogen atoms + 1 Oxygen atom + 2 Hydrogen atoms 1 Oxygen atom 4 Hydrogen atoms 2 Oxygen atoms

Energy of Reactions Energy- the ability to do work Types of energy: -heat -light -sound -electricity All Chemical Reactions will either give off energy or take in energy.

Endothermic and Exothermic Reactions EXOTHERMIC Chemical reaction that releases heat Heat exits/goes out of the reaction Feels hot to the touch Sample Equation: A + BC + D + heat Examples: burning, hand warmers Mg+HCl (from lab)ENDOTHERMIC Chemical reaction that absorbs heat Heat enters/goes in to the reaction Feels cold to the touch Sample Equation: A + B + energyC + D Examples: cold pack OUT IN HEAT