2.1 Flashcards
Cation
When an atom loses electrons and becomes a positive ion
Anion
When an atom gains electrons and becomes a negative ion
Why is the mass of a proton/neutron 1u
The mass of carbon-12 is exactly 12u (Atomic mass units)
Relative isotopic mass
Mass of an isotope compared to 1/12th the mass of carbon-12
Relative Atomic mass
Weighted mean mass of an atom of an element compared to 1/12th the mass of carbon-12
Ionise
Give something a charge (usually knocking off an electron)
Relative formula mass
Mass of one formula unit (empirical formula) compared to 1/12th mass of carbon-12
Relative molecular mass
Mass of a molecule compared to the mass of carbon-12
Moles
What amounts of substances are measured in
Avogadro’s constant
6.02*10^23 particles in a mole
Number of atoms in 12g of carbon-12
Molar mass
Mass per mole of a substance
What is molar mass measured in
gmol -1 (Grams per mole)
Equation for no. of moles
Mass (g) / molar mass (gmol -1)
Empirical formula
Simplest whole number ration of atoms of an element in a compound
What is 1 mole of gas at RTP equal to
24 dm3 mol-1
= 24, 000 cm3
Room temperature
25 degrees
Room pressure
1 atm/ 101 kPa
Molecular formula
The number and type of atoms of each element in a molecule
Dissociation
An acid releases a proton/ H+ ion when added to water
Exists as a reversible reaction
Strong acids
Completely dissociate
All of their acidic protons are released
HCl —> H+ and Cl-
Weak acids
Only partially dissociate in water
Only some of the acidic protons are released
CH3COOH —> H+ and CH3COO-
Are organic acids strong or weak
Weak
Alkali
A base that dissolves in water forming OH- ions
Acid
Substances that releases H+ ions when it dissolves in water
When is a salt formed
When the H+ ions (s) of an acid is/are replaced by a metal cation or ammonium (NH4 +)
Base
Proton acceptor
Types of acids
Monobasic - HCl
Dibasic - H2SO4
Tribasic - H3PO4
Different acids have different numbers of acidic protons
Acid + metal —>
Salt and H2
Acid + carbonate —>
Salt and CO2 and H2O
All nitrates and Group 1 salts are …
Soluble
Carbonates are …
Insoluble
Redox rules
Atoms in an element always have an oxidation number of 0
In a simple ion, the oxidation number = charge
Adding up all the oxidation no. of the atoms in a compound will give you 0
In a complex (polyatomic) ion adding up all the oxidation numbers of the atoms in the ion will give you the charge
Oxidation
Loss of electrons
Oxidation no. increases
Reduction
Gain of electrons
Oxidation number decreases
Reducing agent
The species that is oxidised
Oxidising agent
The species that is reduced
Disproportionation
When an element is both oxidised and reduced
Oxidation number for uncombined elements
Zero
Special oxidation numbers
Hydrogen is usually +1 except in metal hydrides (AlH3, -1)
Fluorine is always -1. Other halogens can be -1, +1, +3, +5 or +7
O in peroxides = -1
O bonded to F = +2
Molar gas volume
The volume per mole of gas molecules at a standard temperature and pressure
Anhydrous
Containing no water molecules
Water of crystallisation
Water molecules that are bonded into a crystalline structure of a compound
Atom economy
Sum of molar masses of desired products/sum of molar masses of all products
Percentage yield
Actual mass/theoretical mass * 100
Why do isotopes have the same chemical properties
Same electronic configuration
Equation for volume of gas
24 * n = V dm^3
Units for concentration
Mol dm-3 or g dm-3
Units for energy
J
Units for enthalpy
KJ mol-1
Units for mass
g
Units for rate of reaction
Mol dm-3 s-1
Units for volume
Cm3 or dm3
PV = nRT
P in Pa
V in m^3
T in Kelvin
Assumption w water of crystallisation calculation
All the water has been lost - heat repeatedly until mass no longer changes
No further decomposition of the salt - diff to judge if no colour change
Dissociation in H2SO4
H2SO4 –> H+ + HSO4-
HSO4- H+ + SO4 2-
Sim dissociation for H3PO4
