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27 Cards in this Set
- Front
- Back
- 3rd side (hint)
ELEMENT
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Cannot be broken down into simpler substances by either physical or chemical means
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Can exist as atoms (Na) or as molecules (Nitrogen, N2)
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MOLECULE
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It is the smallest electrically neutral particle, of an element or compound that can exist on its own.
Example: water (H2O) - compound / oxygen (O2) - element It is also the name given to the smallest part of those elements which do not exist as atoms in the free state Example: hydrogen H2, Nitrogen N2, F2, Cl2, Br2 |
Ionic compounds do not exist as molecules
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Ion
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An atom or group of atoms which carry an electrical charge
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COMPOUND
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A substance formed when two or more elements chemically combine together
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Have properties that are different from its component elements
Can be broken down into simpler substances by chemical methods. |
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ISOTOPES
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Atoms of the same element having same proton number but different neutron number
Example: 35-Cl and 37-Cl |
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Empirical Formula
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Smallest whole number ratio of atoms in a compound
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Molecular Formula
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Actual number of atoms in a compound
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1) Calculate empirical Formula mass
2) divide molecular mass by empirical formula mass 3) Molecular Formula = (empirical formula)*n |
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Atomic Mass unit
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Mass of a carbon-12 atom divided by 12. This is the standard reference scale to measure mass of atoms and molecules
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Relative Atomic Mass
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The weighted average mass of an atom of that element divided by the 1/12th the mass of a carbon-12 atom.
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Relative molecular mass
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The sum of the relative Atomic Masses of all the atoms in the chemical formula
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Relative Isotopic Mass
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The mass of an atom of that isotope divided by 1/12th the mass of a carbon-12 atom
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Mole
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Amount of substance which contains the same number of particles (atoms, ions, molecules) as there are carbon atoms in 12g of carbon-12)
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Avogardro's Constant
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The number of particles in a mole
1 mole = 6.02x10²³ particles (atoms ions or molecules) |
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Molar mass
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Molar mass of a substance is the mass of one mole in grams
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Number of moles = mass in grams / molar mass of atoms
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Molar volume
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Volume occupied by one mole at room temperature and pressure
=24dm³ at rtp |
Number of moles = volume of gas / molar volume
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Concentration
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Measured in moles per cubic decimeter (mol/dm³)
1 litre = 1 dm³ = 1000 cm³ |
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1M [of NaCl]
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Means that each dm³ of the solution contains 1 mole (58.5g) [of NaCl]
OR ITS CONCENTRATION IS 1 mol/dm³ |
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Molarity
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Concentration in mol/dm³
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Molarity = moles of solute / volume of solution
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Conversion to g/dm³
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Molarity x molar mass of solute
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Parts per million
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Equivalent to one milligram of something per kg of solvent
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Salts
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Consist of lattice of positive and negative ions
Salts with water of crystallisation are hydrated salts Formed by the reaction between an acid and a base |
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Double Salts
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Crystals that contain two different salts (two different anions or cations)
Mixing two different salts and crystallising it would form a double salt Example: when iron (II) sulfate solution is mixed with ammonium sulfate solution, the salt ammonium iron (II) sulfate is formed It can also be formed from raw materials using iron, ammonia, and sulfuric acid |
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Percentage yield
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Used to measure the efficiency of a reaction.
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Theoretical yield
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Mass of product that should be formed
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Can be calculated using mass of reactants and chemical equation
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Actual yield
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Experimental yield - actual mass of product formed
Always less than the theoretical yield. Because ~all the reactants do not undergo complete reaction ~some product is lost during handling ~solution loss during filtration or during transfer between containers |
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Atom Economy
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Also used to measure efficency of reaction.
It is a measure of the proportion of reactant atoms that become a part of the desired products rather than by products |
A reaction that has a very high yield could still be very wasteful if a lot of the atoms of the reactants form other products
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Atom Economy in addition and substitution reactions
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Addition reactions have 100% atom economy since ONLY ONE PRODUCT is formed and NO atoms are WASTED AS BY-PRODUCTS
Substitution reactions have lower atom economy than addition reactions since at least two products will be formed, where only one product is the desired product |
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