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Transcript
Chapter 2- Matter (has mass & takes up space) Physical Properties • matter that can be observed w/out changing the identity. ex. Color, odor, mass, volume, state, freezing, melting, & boiling point, and….. • Thermal conductivity – • • • ability to transfer thermal energy Malleability – can be pounded into sheets (aluminum foil) Ductility – can be drawn or pulled into a wire. Solubility – can dissolve in another substance • Density is mass per unit volume Formula D = m V Density of one substance is usually different from another. Good Egg vs Bad Egg Density of Good Egg = 1.2 g/ml Density of Bad Egg Density of water = .9 g/ml = 1.0 g/ml Result= Bad Egg Floats Changes in matter: Physical vs Chemical Physical Change – does not form a new substance (most can be undone) Chemical Change – does form a new substance CANNOT BE UNDONE Chemical changes often involve: • • • • • Color changes Fizzing/foaming Change in temp. Sound/light Odor Chemical Properties the ability to change into a new substance w/ different properties. i.e. Wood burns and becomes smoke & ash Chemical Properties • Flammability – ability to burn • Non-flammability – cannot burn • Reactivity with - gas acid water Elements-found on the periodic table An element is a pure substance that cannot be broken down into other substances. (made of only one type of atom) Ex. C, H, O, S, or Fe Elements composed of atoms. Atoms –basic particle from which all elements are made Compounds – a pure substance made of two or more elements chemically combined in a set ratio. (different properties than single elements) H2O, CO2,C6H12O22 Chemical formula-shows ratio (shorthand) Mixtures – made of two or more substances not chemically combined. Heterogeneous - you can see the different parts Homogeneous – evenly mixed that you cannot see the different parts. Example= solution Mixture Separation Magnet Filtering Distilling Evaporation What is Energy • Energy is the ability to do work…. – And that work causes an object to move in the direction of the force. – It is expressed in units called Joules (J) Forms of Energy 1. Chemical – energy 2. required to bond matter particles together (toasting marshmallows) Thermal – is the total kinetic energy (energy of motion) of the particles of an object (from hot to cold) Thermal Imaging Chemically bonded atoms 3. Electromagnetic (radiation) travels through space as waves ex. Radio, heat, & micro 4. Electrical- electrically charged particles move from one place to another Endothermic vs Exothermic Endothermic – energy is absorbed i.e. Melted cheese sandwich – the cheese takes in energy to melt. The sun is also endothermic. Exothermic – energy is released i.e. Welding of any kind releases energy in form of sparks and heat Endo vs Exo Graphs Endothermic Reaction Activation energy-the amount of energy required to start a reaction