atomic structure and amount of substance

• ionisation - the process of an electron being removed from 1 mole of a atom or molecule.
• what are electron shells called in AQA?

  main energy levels
• second ionisation energy - the amount of energy required to remove one more electron from one mole of cations (positive ions), forming one mole of dications (double positively charged ions).
• what are atomic orbitals?

  a region around the nucleus that can hold up to 2 electrons with opposite spins.
• an electron is considered to be negatively charged
• when an electron is removed from an atom then the atom will be positve
• electron configuration - the arrangement of electrons within the different energy levels/shells of an atom, including sub-levels such as s, p, d and f orbitals.
• the first ionisation energy is always greater than the second ionisation energy because it requires removing two electrons, which means there's less attraction between the remaining positive charge and negative charges left over by the other electrons.
• atomic number = proton number = mass number - neutron number
• when an electron is gained into an atom then the atom becomes negative
• what's the relative mass of protons?

  1
• what's the relative mass of neutrons?

  1
• whats the relative mass of electrons?

  1/2000
• mass number is the total number of protons and neutrons in the nucleus
• atomic number is the number of protons in an element
• protons are positively charged while neutrons are negatively charged which makes the atom neutrally charged
• isotopes are atoms with the same number of protons but different number of neutrons but has the same atomic number
• relative mass is the mass of an atom that's compared with 1/12 of the mass of carbon 12
• what's relative isotopic mass?

  the number of mass
• shielding electrons are electrons that shield the nucleus from the electrons that are trying to pull them out
• what factor affect the ionisation energy?

  atom size, nucleus charge and electron shielding
• what's the order of electrons in each shell in the element?

  2,8,2
• mass spectrometry is a chemical analysis used to determine the identity of a unknown compound and to determine the relative abundance of different compounds
• time of flight mass spectrometry: uses a beam of electrons to ionise the sample and then measures the time taken for the electrons to travel through the sample
• method for time flight: 1. ionisation, 2. acceleration, 3. ion drift, 4. data analysis
• an ion is a molecule that has a positive or negative charge.
• cations are when there's a positive charge and anions are when there's a negative charge
• mole - the amount of a substance that contains the same number of particles as there are atoms in 12 grams of carbon-12
• molar mass is the mass of one mole of a substance in grams
• how do you calculate mass?

  number of moles x molar mass
• the concentration of a solution is how much solute is in a known volume of solvent
• how many cm3 are in 1dm3?

  1000
• the molar mass volume is 24dm3 mol-1. standard conditions are 298k and 100kpa
• how do you calculate the number of moles in a gas?

  volume /molar gas volume
• in ideal gases the intermolecular forces are negligible
• whats the equation for the volume of particles?

  pv=nRT
• what does pv=nRT stand for?

  p = pressure, v = volume, n = number of moles, R = gas constant, T = temperature
• percentage yield is used to measure the effectiveness of the synthesised process
• equation for percentage yield?

  actual yield/ theoretical yield x 100
• the percentage from the percentage yield indicates how effective the chemical reaction was