2.1 - Atoms Ions And Compounds Flashcards
Isotope def
Isotopes are atoms of the same element with the same atomic number, but with a different number of neutrons, resulting in a different mass number
Relative atomic mass def
The weighted mean mass of an atom of an element, relative to one-twelfth of the mean mass of an atom of carbon-12
Relative isotopic mas
The isotopic mass of an isotope relative to one-twelfth of the mean mass of an atom of carbon-12
Relative molecular mass def
The weighted mean mass of a molecule of a compound, relative to one-twelfth of the mean mass of an atom of carbon-12
Ions to remember
NO3^- SO4^2- CO3^2- OH^- NH4^+
How many particles in one mole(Avogadro’s constant)
6.02x10^23 particles in one mole
Useful moles equations
-Moles=mass/Mr
-Moles=concentration x volume/1000
(Only when converting dm^3 to cm^3)
Moles = volume(dm^3)/24
Empirical formula def
The simplest whole number ration of atoms of each element present in a compound
Molecular formula def
The number and type of atoms of each element in a molecule
The true number of each atom on the molecule
What is an anhydrous substance?
Substance that contains NO water of crystallisation
What is a hydrated substance?
Substance that contains water of crystallisation
What is a standard solution?
A solution of known concentration
What is the limiting reactant in a reaction?
The reactant that is not in excess
Ideal gas equation
pV = nRT Where: p = pressure in Pa V = volume in m3 T = temperature in K n = moles, mol m = mass, in grams R = ideal gas constant - 8.31
-Only under standard conditions
-Temp: 298K/25C
Pressure: 100kPa/101kPA
What is the value for the ideal gas equation?
8.31
How to work out percentage yield
Experimental mass/theoretical mass x 100
How to work out atom economy
Mr of desired product/Mr of reactants x100
Why is a higher atom economy more desirable to manufacturers?
- The higher the atom economy, the less waste product there is
- So process is more economically viable for industrial scale manufacture
- Helps to preserve raw materials as well
Def of an acid
Substance that releases H+ ions in aqueous solution
Def of an alkali
Substance that releases OH- in aqueous solution
Def of a base
Substance that accepts H+ ions from an acid in aqueous solution
Common acids to know:
-HCl - Hydrochloric Acid
-H2SO4 - Sulfuric Acid
-HNO3 - Nitric Acid
-H3PO4 - Phosphoric Acid
CH3COOH - Ethanoic acid
Common bases to know:
- NaOH - Sodium Hydroxide
- KOH - potassium hydroxide
- NH3 - Ammonia
Difference between strong and a weak acid
- A strong acid fully dissociates in aqueous solution
- A weak acid partially dissociates in aqueous solution
What is a neutralisation reaction?
Reaction of an acid with a base that usually produces a salt
Common reactions between acids and bases
CASHOCO:
Acid + Carbonate —> salt + water + CO2
MASH:
Metal + acid —> salt + hydrogen
BASHO:
Base/metal oxide + acid —> Salt + water
Potential errors in creating a standard solution
- Systematic errors on balance reading
- lost substance transfer
- Overfilling of volumetric flask
How to reduce errors when creating standard solution
- Read volumes from bottom of the meniscus
- Washing methods
Oxidation number rules
- Oxidation number of an element is 0
- Oxidation numbers in a neutral compound add up to zero
- Oxidation numbers in a charged compound add up to the total charge
- Hydrogen has ox number of +1
- Oxygen has ox number of -2
- All halogens have an oxidation number of -1
- Group 1 metals have an oxidation number of +1
- In metal hydrides, the ox number of hydrogen is -1
- In peroxide’s, the ox number of oxygen is -1
What is oxidation?
Loss of electrons
What is reduction?
Gain of electrons
Simple acronym to remember Redox reaction
OILRIG
Oxidation is loss(of electrons)
Reduction is gain(of electrons)
What is an oxidising agent?
- A substance that accepts electrons from the species being oxidised
- Therefore it gains electrons and the oxidising agent itself is reduced
What is a reducing agent?
- A substance that donates electrons to the species being reduced
- Therefore it loses electrons and the reducing agent itself is oxidised
What is a disproportionation reaction?
- When a species in a reaction is both oxidised and reduced.
- when oxidation number increases and decreases in separate occasions in the reaction
