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The Chemistry part of Science 9 Section 1.2 WHAT IS CHEMISTRY ANYWAY ?! You mean other than awesomely awesome?! Chemistry is ... The study of the properties, composition and behaviour of matter… PROPERTY VS COMPOSITION Property is a characteristic, a trait or quality that something has Ex: water boils at 100 °C Composition is what something is made up of…its basic nature from the inside (its ingredients) EX: water is made up of two hydrogen atoms and 1 oxygen atom H20. MATTER MATTER is anything that has _____________ and occupies ______________ Mass is the amount of ___________ in a substance or object. Mass is often measured in grams(g) or kilograms(kg) Volume is the amount of ______________a substance or an object occupies. Volume is often measured in litres (L) or mL Ex: This bottle holds 250mL of liquid Describing Matter Pure Substances: a substance that is made up of only one kind of matter. There are two kinds of pure substances: a) Element - a pure substance that cannot be broken down or separated into simpler substances Ex: gold (Hg) silver(Ag) b) Compound - a substance composed of at least two elements Ex: water (H20), CO2 See pages 22 - 23 HOW DO WE DESCRIBE MATTER? We describe matter by looking at their properties and composition. We collect information on them. This information can be qualitative or quantitative Describing substances Qualitative information is ___________________ information Quantitative information is __________________ information PROPERTIES, COMPOSITION AND MATTER Property is a characteristic, a trait or quality that something has Ex: water boils at 100 °C Composition is what something is made up of…its basic nature from the inside (its ingredients) Ex: water is made up of two hydrogen atoms and 1 oxygen atom H20. PHYSICAL PROPERTIES They are characteristics of matter that can be observed and measured. They are either qualitative or quantitative. Examples: state, colour, magnetism, density, melting point, boiling point, etc… Different properties for different matter make them unique and valuable. Ex: glass is not a good conductor of heat or electricity, does not form crystals, can easily be bent or shaped when heated…this makes it perfect to use for window glass!!! PHYSICAL PROPERTIES EXAMPLES: DUCTILITY The ability to be stretched or drawn into wires PHYSICAL PROPERTIES EXAMPLES: VISCOSITY Resistance to FLOW ! Doesn’t wanna move! viscous = lazy PHYSICAL PROPERTIES EXAMPLES: MALLEABILITY The ability to be rolled or hammered into thin sheets PHYSICAL PROPERTIES EXAMPLES: DENSITY Density: describes how tightly packed things are together in a particular space/volume. Density= mass volume Which box looks more dense?? CHEMICAL VS PHYSICAL CHANGES Matter can go through changes.. There are two kinds: physical and chemical changes How do we know which is which? ! Chemical Change A chemical change is a change in matter that occurs when substances combine to form _______________ The new substance has completely different chemical and physical properties from what you started with. Ex: burning, explosions fireworks, cooking rusting Chemical Change In chemical changes, THE CHANGE IS NOT REVERSIBLE! (NEW matter with NEW properties) Goodbye my love, goodbye! Physical Change (state change) When a physical change occurs, no new substances are formed ( just the appearance changes) -size, shape or state changes Examples: Cutting paper Chopping tomatoes Melting ice/freezing water. Physical Changes are just changes of State In other words, when water turns from liquid(state) to ice(state), it is still water with the same chemical formula H2O. So the chemical formula has not changed at all so the essence is the same, only the appearance is different! Are the following chemical or physical changes? A piece of wood burns to form ash_________ Water evaporates into steam__________ A piece of wood is cut in half___________ A bicycle chain rusts ____________ Food digested in the stomach ___________ LET US CHECK OUR UNDERSTANDING Physical and chemical changes check! http://vital.cs.ohiou.edu/steamwebsite/downloads/ ChangeLab.swf STATES OF MATTER Matter can exist in three common states or phases:_______, _______, and _______. http://www.chem.purdue.edu/gchelp/liquids/character.html ARE THERE OTHER STATES OF MATTER THAT EXIST ?! FOR YOUR INFORMATION ONLY THERE ARE ALWAYS CHANGES OF STATES Things change! Matter can change from liquid to solid, solid to liquid, etc when energy is added or taken away… We need to know these terms regarding those changes IMPORTANT POINTS WHEN STATES CHANGE Boiling temperature/boiling point: Temperature at which a liquid turns into ________ . Freezing point: Temperature at which a ______ turns into a ____________ Melting point is the temperature at which a ____________ turns into a _______________ AND SOME MORE… Condensation: Temperature at which a _____turns into ________ Sublimation : Temperature at which a ____________ turns into a _______________ Deposition :Temperature at which a ____________ turns into a _______________ SOMETHING TO THINK ABOUT At what temperature does water solidify or freeze? At what temperature does water melt ?? MODELS TO EXPLAIN MATTER Scientists like to understand and explain things… There have been many models to explain matter and how it behaves. Today we will learn about a few of them … The Particle Model of Matter 1) Describes the behaviour of matter 2) Matter is made of small particles. There are spaces between the particles. Gases have more space than liquids. Liquids have more space than solids. 3) Particles are always moving. 4) Particles are attracted to each other. The strength of attraction depends on the type of particle. See page 18 The Kinetic Molecular Theory See page 19 The main points in the theory are: 1) Matter is made of small particles. 2) There is empty space between particles. 3) Particles are constantly moving. a) Solid particles are packed together and cannot move freely. They can only vibrate. b) Liquid particles are farther apart and can slide past each other. c) Gas particles are far apart and move around quickly. 4) Energy makes particles move. The Kinetic Molecular Theory and Changes of State Solid Particles are close together, fixed in position and vibrating. Melting As temperature increases, particles’ kinetic energy increases. Liquid Particles are still close, but slide past one another. Boiling As temperature increases, particles’ kinetic energy continues to increase, creating more space. Gas Particles are spaced out, and highly energetic. They move freely. See page 20 Homework Page 27 #1,2,3,6,8. That’s it !!! You survived your first lesson