BCH 261 Lecture Notes - Lecture 12: Nitric Acid, Ph Indicator, Hydrobromic Acid

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22 Nov 2020
Practical Exam Study Guide
Unit 1: Matter, Chemical Trends and Chemical Bonding
Periodic Trends
- Atomic Radius: The distance from the centre of the atom (nucleus) to the valence shell. (right to left; decreases, down;
- Ionization Energy: Energy required to remove ONE electron from the valence shell of a neutral atom. (left to right;
increase, up; increase)
- Electron Affinity: The amount of energy released when a neutral atom GAINS an electron to form a negative ion (left to
right; increase, up; increase)
- Electronegativity: The electron attracting ability of an atom (left to right; increase, up; increase)
Electron Shells: Electrons only exist where electron shells, or energy levels, allow them to. A difference in the number of energy
levels affects the distance electrons can be from the nucleus.
Nuclear charge: Number of protons determines the positive charge in the nucleus. A different number of positive charges in the
nucleus changes the pull on electrons. - Less protons so the attraction with electrons are weaker
Shielding: Electrons are attracted to the nucleus. Inner electron shells block, or “shield” the attractive force between outer electrons
and the nucleus, occurs b/c like charges repel
Intramolecular Forces: the forces that hold the atoms to each other - ionic and covalent bonds
Polarity: one of the atoms applies/has a stronger attractive force on the electrons in the bond
- Non-Polar Bonds: equal sharing of the bond electrons, the electronegativities of the atoms are equal
-Polar Bonds: an uneven attractive force on the electrons between the atoms, polar molecules are only observed in
molecular compounds
- Electronegativity Equation: EN = EN1 - EN2
- Polarity Scale: Covalent (0-1.7), Ionic (1.7-3.3), Non-Polar; two identical non-metals (0-0.4), Polar; unequal sharing of
electrons, two different non-metals (0.4-1.7), Ions; complete transfer of electrons, metal + non-metal (1.7-3.3)
Intermolecular Forces: forces that attract molecules to each other, attract covalent compounds
- London Dispersion: weakest force, temporary dipoles which attract the molecules. (ie. H - H IIII H - H)
- Dipole-Dipole: medium force, a molecule with dipole interacts with another molecule with dipole. (ie. H - Cl IIII H - Cl)
- Hydrogen Bonding: strongest force, X
- H, where X
is N, O, F - have high electronegativity. (ie. H - F IIII H - F)
*Dipole: when an element is more electronegative than the other in a bond
Unit 2: Chemical Reactions
Types of Chemical Reactions
Synthesis, Decomposition, Single Displacement, Double Displacement, Neutralization, Incomplete/Complete Combustion
Predict Products for Different Types of Chemical Reactions (including states)
- Neutralization: acid + base a salt + water
Reactivity Series
- Metal activity series is used during single displacement reactions
- When the metal is MORE REACTIVE than the other metal which is already bonded to an element/compound, this MORE
REACTIVE metal will switch places with the other element. No reaction will take place, if the metal is LESS reactive than
the bonded metal compound.
Unit 3: Quantities in Chemical Reactions
How to Use Avogadros Constant to Determine the Number of Atoms, Molecules or Formula Units (n=N/N
- n = number of moles n=N/N
A n=m/M
- N A = Avogadros constant N
=N m=n·M
- N = number of atoms, molecules, or formula units N=n
g (Molar Mass) moles (6.02
x 10^23) atoms, formula units, molecules
Percentage Composition (mass percent): the atomic mass of an element divided by the total mass of the compound, then multiply
by 100%
Hydrate: 1. Find the mass of the water driven off by the mass of hydrate - the mass of anhydrate = mass of water
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