Chemistry A Unit 2 Notes PDF

Chemistry A Unit 2 Notes Please write down the vocabulary for each lesson and add to these as necessary as you go through the pages of the lessons. Lesson 2 Two types of properties of matter: Chemical properties - describes how matter reacts (or doesn’t) Ex: Flammability Physical properties...

Chemistry A Unit 2 Notes Please write down the vocabulary for each lesson and add to these as necessary as you go through the pages of the lessons. Lesson 2 Two types of properties of matter: Chemical properties - describes how matter reacts (or doesn’t) Ex: Flammability Physical properties - can be observed without changing the composition of the matter. Ex: color, hardness Two types of physical properties - Intensive - color, density, melting point, luster, malleability. These do not depend on how much of the substance you have. Extensive - change based on the amount of matter - mass and volume Physical changes - doesn’t change the composition of the matter. Melting, boiling, freezing, Chemical changes - you get something new - the composition of the matter changes. Burning, Rusting, change in color, basically any chemical reaction. Pure substances - have a single chemical composition. Atoms, molecules, elements. Atoms - the type is determined from the number of protons - see periodic table. Molecules - two or more atoms bonded together Element - can be atoms or diatomic molecules like O2. One type of atom. See picture on page 8 of lesson 2 Mixtures - components are not chemically combined Compound - elements are chemically combined Two types of mixtures Homogeneous mixture - ingredients mix uniformly. It looks like one thing. Salt water. Heterogeneous mixture - ingredients don’t mix uniformly - pizza, chicken noodle soup, Lesson 3 Separating mixtures Filtration - using a filter to separate based on size of particles Distillation - separates liquids based on their boiling points. See diagram on page 3. Evaporation - Liquid turns into gas, and could leave behind a solid Chromatography - Separates particles based on size and how fast they move. Lesson 4 Atoms are made up of protons, neutrons, and electrons. Protons - Positively charged, in the nucleus Neutrons - neutrally charged, in the nucleus Electrons - negatively charged, outside the nucleus. See picture on page 2 Protons determine the element. This is the atomic number. Mass number is the number of protons and neutrons. Elements can have different numbers of neutrons and still be the same element. Isotopes - same element (same number of protons) and different numbers of neutrons and therefore, different mass numbers. An atom is neutral because the number of protons is equal to the number of electrons. Ion - atom with a positive or negative charge. Atoms gain or lose electrons to form ions. They DO NOT gain or lose protons. Open the simulation on page 2, and follow the directions on page 3. Lesson 5 Molecules - group of atoms that are bonded together. Crystals - an ordered 3-d arrangement of atoms, ions, or molecules. Table salt and diamond are examples.. Polymer - long repeating chains of molecules. Covalent bonds. Plastic, lipids (fats), and starches are examples. Structural formulas - a way to diagram the structure of organic molecules in organic chemistry. Can be very helpful in depicting polymers as you can just draw one unit and indicate how many times it repeats in the polymer. Lewis dot structure - a way to diagram simple molecules Ball and stick models - used to represent crystals Ribbon diagrams - show 3d structures of proteins which are very large, complex molecules. Open the simulation on page 3, and look at different types of molecules VSEPR - valence shell electron pair repulsion theory Electrons are negatively charged and repel each other. In molecules, some electrons are shared, and some are not. These unshared electrons are lone pairs of electrons. These electrons repel bonded electrons. Electrons want to be as far away from one another as possible. This determines the shape or geometry of the molecule. The bond angle is the angle formed by the positions of the chemical bonds joining a central atom to two other atoms Molecule shapes Linear - bond angle is 180° Trigonal planar - bond angle is 120° Tetrahedral - 3-d molecule. Bond angle is 109.5° Trigonal bipyramidal - various bond angles Octahedral - bond angles may be 180° or 90° See diagram on page 7 - only pay attention to the first column Open the simulation on page 7 and follow the instructions on page 8 and answer the questions on page 9 and 10.