Chem Final.docx - Outline of Main Topics in CH 1010/1020...

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Outline of Main Topics in CH 1010/1020 • Focus on the molecular level picture of all of this, and not on plugging numbers into equations. • This list is definitely not exhaustive but should point you to most of the main topics. • If you need more explanation about any of these topics, come see me. Fundamentals Molecular level difference between chemical and physical changes Chemical changes involve the breaking and forming of bonds (intramolecular forces: covalent, ionic, and metallic bonds) between the atoms of a molecule. The parts that make up a molecule are separated and reformed with other atoms to produce a different compound Physical changes involve the breaking and forming of intermolecular forces (van der Waals, dipole-dipole, ion-dipole, and hydrogen bonds) between molecules of the same compound; maintains chemical formula For different phases of mater, the particles have different relative amounts of kinetic energy From lowest to highest: solid < liquid < gas Solid – has fixed shape and volume Liquid – takes shape of container, has fixed volume Gas – expands to fill container (no fixed shape or volume) Changes in State Solid to liquid = melting Liquid to gas = vaporization Solid to gas = sublimation Gas to liquid = condensation Liquid to solid = freezing Gas to solid = deposition Density (molecular level picture and how it is calculated) Density – a measure of how tightly packed the particles in a substance are D = mass/volume Bond length Single bonds are the longest and weakest Double bonds = medium Triple bonds are the shortest and strongest More bonds/higher bond order means the more dense the molecule Atom size – the smaller the atoms are, the more tightly packed they can be, therefore more dense Crystal structure – in the case of water, the crystal structure of ice has a 105 degree bond angle between atoms, leaving room for air, which makes ice less dense than water (floats)
Accuracy vs Precision Accuracy – agreement between measured value and the accepted/true value Precision – agreement among repeated measurements (consistency) Identifying rxn types: Acid/base neutralization Acid + base salt + water Redox Precipitation Double-displacement reactions when two aqueous solutions mix to form one soluble compound and one insoluble compound Combustion Substance + O 2 CO 2 + H 2 O Atomic Structure Protons, neutrons, electrons Where located in atom Protons – nucleus Neutrons – nucleus Electrons – electron cloud Determine size of atom? The number of protons determines the size of the atom because a higher number produces a stronger attractive pull of the electrons reduces the overall size of the atom Determine mass of atom? Mass number of atom = # of protons + # of neutrons Nuclide symbols Ions – atom or group of atoms with a net positive or negative charge (# of protons does NOT equal # of electrons) Cations – positive charge, more protons than electrons Anions – negative charge, more electrons than protons

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