IB Chem

Elements without an isotope

Fluorine

Mass spectrometer

Used to determine the relative atomic mass of chemicals. To calculate, you take the data (isotopic masses and their abundance percentages), multiply them by each other, then add them together

Electron Configuration Exceptions

Chromium and Copper.

Schrodinger Model of the electron

Proposed a wave equation for electron behaviour and the use of atomic orbitals

Atomic orbital

A region around an atomic nucleus in which there is a 90% probability of finding the electron. Shape is dependant on the energy of the electron.

Electron spin

The way that an electron spins on its own axis. Upward arrow for clockwise, downward for counter-clockwise

Pauli exclusion principle

States an orbital can only hold two electrons of opposite spin

Aufbau principle

That electrons are placed into orbitals of lowest energy first

Hund's third rule

Electrons in the same orbital layer are placed separately to minimize mutual repulsion between them

S-orbitals

sphere shaped. Max 1 (2 e-).

D-orbitals

weird shaped. Max 5 (10 e-).

P-orbitals

dumbbell shaped (figure eight/infinity). Max 3 (6 e-).

F-orbitals

max 7 (14 e-).

Hydrated salt

Compounds with a fixed ratio of water molecules in the crystalline structure

Water of crystallization

The water molecules in a hydrated salt

Anhydrous salt

The salt part of a hydrated salt

Hydrated

When molecules are ionized and surrounded by water

Effective charge

The amount of charge which actually attracts outer electrons, as they area shielded by the inner ones. = Protons

Allotropes

Different bonding and structural patterns of the same elemnt in the same physical state. Ex. Molecular oxygen (O2) and Ozone (O3)

Diamond

Each carbon bonded to four others. Tetrahedral. Non-electrical conductive, thermal conductive. Transparent, lustrous. Hardest known natural substance, brittle, high melting point

Graphite

Each carbon boned to 3 others. Parallel planes of hexagons. Delocalized electrons and can slide over each other. Conductive of electricity, non-conductive of heat. Non-lustrous, grey. Brittle, high melting point, most stable

Graphene

Each carbon bonded to three others. Two-dimensional hexagons in a single layer. Delocalized electrons. Electrically conductive and most thermally conductive. Almost entirely transparent. Thinnest material to ever exist, strongest to ever exist, flexible, very high melting point. Used in TEM, touch screens, and other electronic devices

Fullerene (C60)

Each carbon bonded to three others. Spherical with pentagons and hexagons. Low thermal and electrical conductivity. Black powder. Light and strong, can react with K to be superconducting, low melting point. Used in lubricants, medical, and industrial devices

Silicone

Elementally bonded to four other silicon in a tetrahedral arrangement. Similar to diamond.

Silicone dioxide (silica, quartz)

Giant covalent tetrahedral structure. Strong, high melting point. Doesn't conduct electricity, insoluble in water. More common than elemental silicone

Methane

Primary constituent of natural gas (as well as nitrogen and sulfur compounds, as impurities). high energy density. Cleanest to burn due to its short chain, emitting the least carbon monoxide, hydrocarbons, and particulates.

Crude oil

Mixture of straight-chain and branched-chain saturated alkanes, cycloalkans, and aromatic compounds. Formed from marine animal and plant remains trapped under rocks, high temperature and pressure.

Biofuels

Fuels produced from the biological fixation of carbon over a short period of time. Renewable and sustainable. Ex. Photosynthesis creating glucose

Gasohol

A mixture of 10% ethanol and 90% unleaded gasoline.

Advantages of biofuels

Cheap and available. Renewable and sustainable. Less polluting than fossil fuels.

Disadvantages of biofuels

Uses land. High cost of harvesting and transportation. Takes nutrients from soil. Lower specific energy than fossil fuels.

Fuel cell

Where reactants are continuously supplies to electodes to produce electricity

Hydrogen fuel cell

Uses hydrogen and oxygen gas as reactants to release energy. Porous carbon with a transition metal as inert electrodes.

Cons of hydrogen fuel cell

Hydrogen gas is almost never found in nature. Extracting it from hydrocarbons, fossil fuels, and biomass gets hydrogen but also carbon dioxide. It can also be extracted through electrolyzing water, but… if we had the energy we wouldn't be in this situation.

Direct methanol fuel cell (DMFC)

Methanol is oxidized under acidic conditions on a catalyst surface to form carbon dioxide. H+ ions are transported across a proton exchange membrane from anode to cathode, with electrons transported through an external circuit from anode to cathode, reacting with oxygen to produce water. Water is consumed at the anode and produced at the cathode

Quenching

Where a substance is introduced to stop the reaction at the moment it is withdrawn to get a specific time.

Maxwell-Boltzmann Energy Distribution Curve

Shows the number of particles with kinetic energy vs. the amount of kinetic energy they hold in a gas

Amphiprotic

Substances that can act as a bronsted-lowry acid and base in different reactions

Effervescence

When reactions involve a gas and produce bubbles

What is a radical

Radical

Radicals

Cl, Br, H, Nitric Oxide, Hydroxyl radical, methyl radical, superoxide radical, benzene radical anion, propane cation, ethanol cation

Homolytic fission

When a covalent bond breaks to form two radicals, with both products having an equal assignment of electrons from the bond

Thermolytic fission

Homolytic fission by heating the compound, for weaker bonds

Photolytic fission

Homolytic fission through high-energy UV light, for stronger bonds

Chlorofluorocarbons

When entering the stratosphere, are broken down to release reactive chlorine radicals. C-Cl bond breaks before C-F because it has lower bond enthalpy.

Radical substitution reactions

When formed from alkane substitution, start a chain reaction form a halogenoalkane. Intiate (usually photolytic fission); propagate (react with other species to form new radicals); terminate (form covalent bonds, revers homolytic fission, gets rid of radicals)

What is a Nucleophile

A reactant that forms a coordination covalent bond to its reaction partner by donating bonding electrons

Neutral nucleophiles

water, ammonia, alcohols, amines

Charged nucleophiles

hydroxide, F-, Cl-, Br-, I-, CN-, R-

Electrophile

The nucleophile's bonding partner, forming a covalent bond by accepting bonding electrons. Note that not all molecules are electron deficient, but can act as electrophiles in addition reactions (e.g. Br2)

Neutral electrophiles

hydrogen halides, halogens, halogenoalkanes, water (neutral)

Charged electrophiles

Carbocations, H+, NO2+, NO+, CH3+