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Chapter 1 Science Study Notes Physical Properties -a characteristic or description of a substance that can be used to identify it. The States of Matter -a physical property, can be solid, liquid, or gas. Hardness -the physical property of a solid that is the measure of its resistance to being scratched or dented- ex diamond is very hard , chalk is not very hard Malleability -the physical properties that allows the shape of a solid to be changed (gold is malleable) Ductility -the physical property of a solid that allows it to be pulled into wires EX tungsten . Melting & Boiling point -the physical property of when a substance changes state. Melting -solid-liquid-boiling – liquid –gas Viscosity -the physical property of a liquid that limits its ability to flow. Density -an amount of mass per unit of volume Kg/m3 , g/cm3 , g/ml D=M V Crystal Form - the form of many minerals where you can see a regular pattern of blocks or other shape Solubility - the ability of a substance to dissolve in a solvent(water). Chemical Properties -the characteristic behaviour that happens when one substance interacts with another becoming something new. Combustibility -the chemical property of a substance that allows it to burn when exposed to flame and oxygen. Reaction with Acid -a chemical property of a substance that describes its ability to react with acid. Alloys-a metal made by combining two or more different metals or metals and non-metals. EX steel = iron + carbon Gold jewelry = 14 carat = 58% gold Bronze= copper + tin 1.7 Physical and Chemical Changes Physical change – a change in the state or form of a substance that does not change the original substance Chemical change – the alteration of a substance into one or more different substances with different properties Five clues of a chemical change 1. a new colour appears 2. heat or light are given off 3. bubbles of gas are given off 4. a participate forms (solid from 2 liquids) 5. change is difficult to reverse Chapter 2 Elements and Compounds 2.1 Models of Matter: The Particle Theory Particle Theory All matter is made up of tiny particles The particles are always moving. The more energy they have the faster they move. The particles are attracted to each other. The forces of attraction are stronger when the particles are closer All the particles of one substance are the same. Different substances are made of different particles Pure substance- a substance that contains only one kind of particle Ex. aluminum foil only has aluminum particles or sugar only has sugar particles Mixture – a substance that contains two or more different pure substances Ex. Cookie, or Kool-aid Solution – a mixture made up of liquids, solids, or gases where the solution looks similar to one of the substances and the other is hidden in it Ex Kool-aid or Alloys- a metal made by combining 2 or more different metals Ex Bronze = Copper + Tin Brass = Copper + Zinc Steel = Chromium + Nickel + Iron Heterogeneous mixture – a substance in which the different components are identifiable and can be separated by physical means. Ex cookie or pizza Elements – a pure substance that cannot be broken down into simpler substances Compound – a pure substance that contains two or more different elements in a fixed proportion Ex. Water H2O – 2 Hydrogen with 1 Oxygen Atom – a particle in an element, from Greek atomos means ‘indivisible’ Molecules – the combination of 2 or more atoms 2.3 Putting Metals to Work metals – a solid that is usually shiny and malleable and a good conductor of electricity heavy metals – metals that have a very high density. 2.7 Chemical Symbols and Formulas Chemical Symbol – an abbreviation for the name of an element. It is made up of 1 or 2 letters. The first letter is always capitalized and the second lower case Chemical Formula – the combination of symbols that represents a particular compound 2.8 Atoms, Molecules, and the Atmosphere Air = 78.02% nitrogen (N2) 21.01% oxygen (O2) 0.94% Argon and other gases (Ar) 0.03% Carbon Dioxide (CO2) 2.9 Building Models of Molecules Models – a way to represent a thing or process Bond – represents the forces that hold atoms together Structural diagrams – a drawing to explain molecules in which atoms are represented by chemical symbols and bonds by straight lines connecting the symbols. 2.11 Plant Nutrients and Fertilizers Fertilizers – a chemical substance added to the soil to increase plant growth Nutrients – a chemical compound necessary for growth Photosynthesis – a chemical process during which plants combine carbon dioxide from air, water, and energy from the sun to produce sugars and oxygen gas Word equation – a concise way to indicate a chemical reaction between substances 2.12 Metal Refining and Extraction in Canada Minerals – a naturally occurring compound, sometimes containing metal combined with oxygen, sulfur or other elements Ore – rock containing a valuable mineral Metallurgy – the technology of separating metals from their ores Chapter 3 3.2 Developing Models of Matter 450 BC – Empedocles Theory that matter made up of 4 elements earth air fire water 400 BC – Democritus Thought matter was made up of tiny particles that could not be broken down further. Called particles atoms – Atomos in Greek for indivisible 350 BC – Aristotle Very influential in his time supported 4 element model and so it was the accepted model for 2000 years. 500-1600 AD Four-element model accepted Alchemists - an experimenter who was a combination of a philosopher, mystic, magician, and chemist. They attempted to make gold out of cheap metals. devised chemical symbols invented lab tools 1650 – Robert Boyle Redefined the word element Element – a pure substance that cannot be chemically broken down into simpler substances. He believed air was a mixture not an element. Did not believe the 4 element model 1700s – Joseph Priestly Isolated oxygen but did not realize it was an element. Antoine Lavoisier Using Priestly’s work concluded air is made of oxygen and one or more gases. So air cannot be an element. Henry Cavendish Isolated hydrogen and when burnt in Priestly’s oxygen produced water So water could not be an element. 1808 now accepted that matter is made of elements John Dalton Created an atomic model to explain why elements differ from each other Atomic Model – A theory proposed to explain why elements differ from each other and from nonelements. Dalton’s Atomic Model - 1808 - Matter is made up of atoms, particles to small to be seen - Each element had its own kind of atom, with its own particular mass - Compounds are made when atoms of different elements join to make molecules - Atoms cannot be created, destroyed or subdivided in chemical change 1800s – Micheal Faraday The current model did not explain the fact that some matter has a charge – static Charges – a negative of positive quantity of electricity that builds up on an object Faraday discovered atoms could gain electric charge Ions – an atom that has become charged by gaining or losing one or more electrons The model had to change Modified Atomic Model - Matter contains positive and negative charges - Opposite charges attract, same charges repel - Atoms combine to form molecules because of electrical attractions 1904 – J.J. Thompson Discovered the negatively charged part of atom – electron Modified Atomic Model – Raisin Bun Model - Thompson - Atoms contain particles called electrons - Electrons have a small mass and a negative charge - The rest of the atom is a positive sphere - Electrons are embedded in the sphere, and the entire atom is neutral or uncharged Nagaoka - Planetary Model His model had a positive sphere with electrons spinning around it like the rings of a planet. 1911 – Ernest Rutherford Worked at McGill University in Canada Did an experiment… - Fired positive particles at thin gold foil - Thought they would pass right through - Some bounced back - Must be a small strong positive part to atom, he called it the nucleus Nuclear Model - An atom has a tiny, dense, positive core called the nucleus. - The nucleus is surrounded by mostly empty space with fast moving negative electrons 3.3 Inside the Atom Subatomic Particles – the protons, neutrons, and electrons that make up atoms Protons – particle with positive charge (p+) - Found in nucleus - Mass is 1 Electrons – particle with negative charge (e-) - found in area around nucleus - mass is 1/2000 of a proton - negligible Neutrons – particle with no charge, uncharged (n) - found in the nucleus - mass is 1 Atomic Number – the number of protons in an atom Mass Number – the sum of protons and neutrons in the nucleus of an atom Standard Atomic Notation – an internationally recognized system used to identify chemical substances. Ex. Standard notation is not used in the periodic table. Ion - atom that has become charged by gaining or losing one or more electrons 3.4 Planetary Model of the Atom Niels Bohr – Planetary Model - Electrons move around the nucleus in nearly circular paths called orbits - Electrons in different orbits have different amounts of energy - The further the electron is away from the nucleus the more energy it has - Electrons can only be in the orbits, not between, they can move from one orbit to another - The first orbit holds 2 e-, the second holds 8 e-, and the third holds 8e- Electrons are more stable when they are closer to the nucleus, at a lower energy Orbit or Energy level – a circular path around the nucleus associated with individual electrons Excited state – the condition of an electron when it is energized enough to jump to a higher orbit Ground state – the low-energy state that is the normal orbit of an electron Bohr Diagrams – represents the electronic structure of an element, it shows electrons in orbits around the nucleus in the center, a circle with the element’s symbol. Bohr-Rutherford diagrams – shows the numbers and positions of all the sub atomic particles. It shows electrons in orbits around the nucleus in the center, a circle with the number of protons and neutrons in the element. To draw Bohr-Rutherford Diagrams: 1. Draw the nucleus as a solid circle. 2. Put the number of protons (atomic number) in the nucleus with the number of neutrons (atomic mass – atomic number) under it. 3. Place the number of electrons (same as protons) in orbits around the nucleus by drawing circles around the nucleus. Remember: 1st shell – 2 electrons 2nd shell – 8 electrons 3rd shell – 8 electrons 4th shell – 18 electrons. When atom gain or lose electrons they do so to have a full outer orbit. 3.6 Isotopes and Radioisotopes Isotope – any of two or more forms of an element, both have the same number of protons but have different number of neutrons Radioactive – the state of an unstable element in which nuclei may break apart, ejecting very high energy particles Radioisotopes – an atom with an unstable nucleus Decay – splitting apart of unstable nuclei to produce radioactive particles α particle – alpha particle – helium nuclei with 2 protons and 2 neutrons, cannot go through cardboard β particle – beta particle – high energy electrons, can go through cardboard but not wood γ ray – gamma ray – high energy electromagnetic radiation with no mass, can go through wood but not concrete