Unit 1 Chemistry Notes 2020 PDF

Unit 1- Chemistry What is Chemistry? Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and takes up space. Physical Properties: A physical property is a characteristic or description of a substance that may help to identify it. A qualitative propert...

Unit 1- Chemistry What is Chemistry? Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and takes up space. Physical Properties: A physical property is a characteristic or description of a substance that may help to identify it. A qualitative property is not measured but involves the senses. Ex. Hear, sight, smell, taste, touch A quantitative property is a measurement and has a numerical value. Ex. Temperature, height, mass, volume, density, solubility 1 Physical Change: The substance remains the same, even though it may change state or form. No new substances are made. It can be reversed. Changes of state –solid, liquid, gas. Ex. Ice cube melts. 2 Density problems: 1-Density=mass g, Kg Volume ml, cm3, L D= m there are 3 variables 1 V To solve for V…..we must isolate V m= DV D D 2.m = V D 3. m = D(V) 3 Ex) A zebra has a mass of 10 g and a volume of 100 ml. Calculate its Density. G=Given, R=Required, A=Analysis, S=Solution, and S=Statement G=Given, R=Required, A=Analysis, S=Solution, and P=Paraphrase Given: m-10g V-100 ml remember units are your friend. D=? D= m/V = 10g/100ml =0.1 g/ml Therefore the density was 0.1 g/ml Chemical Properties: A chemical property describes the behavior of a substance as it becomes a new substance. (Normally, with the help of an acid or heat) Combustibility is the ability of a substance to react quickly with oxygen to produce heat and light. Complete vs incomplete**** Can you get the paper back into its original state? NO 4 Chemical Change: A chemical change is a change in the starting substance or substances and the production of one or more new substances. Five Clues That a Chemical Change Has Occurred 1. A new colour appears. 2. Heat or light is given off. 3. Bubbles or gas are formed. 4. A solid material (precipitate) forms in a liquid 5. non-reversible. 5 Chopping Pumpkins into smaller pieces? Is this a physical or chemical change? Although this is hard to reverse, this is a Physical Change, Why? No new substance was produced. 6 Food Composting. Is this a physical or chemical change? Chemical, Why? A new substance(s) was produced. 7 Chemical or Physical? I’m confused! Pop Can fizzing? Is this a Physical or Chemical Change? Or Both? Although bubbles are formed, this is a Physical Change! Why? The CO2 gas is dissolved into the liquid. It’s Carbonated water! But wait… it can also be a Chemical! Why? H2O + CO2 H2CO3 8  Classifying Matter Models of Matter: The Particle Theory: The Particle Theory of Matter –postulates derived from Dalton 1. All matter is made up of tiny particles that have empty s p a c e s between them. 2. Different substances are made up of different kinds of particles, and particles of one substance are identical. 3. Particles are in constant random motion. 4. The particles of a substance move faster as its temperature increases. 5. Particles attract each other. The forces between particles are stronger when the particles are closer together. The Particle Theory of Matter Solid Liquid Gas 9 Pure Substances: A pure substance is made up of only one kind of matter and it has a unique set of properties. It is either an element or compound. Ex. Gold is an element and sugar is a compound. An element is pure substance that cannot be broken down. Ex. Oxygen – the symbol is O A compound is a pure substance that is made from two or more elements that are combined together chemically. Ex. Water (H2O), NaCl Mixtures: A mixture contains more than one type of particle. Ex. Solid – granola bar Liquid – juice Gas – air A mechanical mixture (heterogeneous) is when two or more pure substances are mixed together. It is made up of more than one particle and you can see more than one part. Ex. Chocolate chip cookie 10 Mixtures: A solution mixture (homogeneous) is made up of more than one particle but you can only see one phase. One particle is dissolved in another. The different substances that make it up are not individually visible. Ex. Sugar dissolved in tea A Summary of Matter Classification 11 What type of mixture is this? Mechanical (heterogeneous) Why? You can see more than one phase. -Milk -- Cereal -- Strawberry - and bowl What type of mixture is this? Solution! Why? You can only see one phase. 12