Atomic structure

How has the ATOMIC STRUCTURE evolved over time [5]?

• Boyle: There are some substances that cannot be made simpler - the elements.

• Dalton: Elements are indivisible atoms, that cannot be broken down. Atoms of different elements have different masses.

• Becquerel: Proved that the atom is not indivisible by radioactivity.

• Thomson: Discovered the electron and its charge & mass (1/1840). This proved that there had to be something to account for the rest of the atoms mass. He introduced the Plum Pudding Model.

• Rutherford: Did the gold foil experiment & found that the mass is small and in the centre.

What is the order of the discover of the ATOM [4]?

• electron

• nucleus

• proton

• neutron

How many electrons and orbitals does each SUB-LEVEL [4] have?

→s

Holds 2 electrons, has 1 orbital.

→p

Hold 6 electrons, has 3 orbitals.

→d

Holds 10 electrons, has 5 orbitals.

→f

Holds 14 electrons, has 7 orbitals.

Explain the relationship between 2 ISOTOPES of the same element. Why do the isotopes have identical chemical properties [2]?

• Isotopes have a different number of neutrons but the same number of protons and electrons.

• The amount of electrons determines the isotopes chemical properties.

• The amount of protons defines the element.

What is the definition of IONISATION ENERGY? And the 1st and 2nd ionisation energy?

The energy needed to remove 1 mol of electrons, from 1 mol of gaseous atoms.

• The 1st ionisation energy produces 1+ gaseous ions.

• The 2nd ionisation energy produces 2+ gaseous ions.

What factors affect IONISATION ENERGIES [3]?

• The attraction of the nucleus: more protons = greater attraction.

• The distance of the electrons from the nucleus: the bigger the atom = the further the distance of the outer electron from the nucleus = weaker attraction to the nucleus.

• Shielding: outer shell electrons repell the inner electrons = weaker attraction.

Explain how successive IONISATION ENERGIES in Period 3's GENERAL TREND give evidence for the electron configuration [2]?

Ionisation energies increase across the period due to there being more protons, so there is a greater attraction to the nucleus. Period 3's electron shielding still remains similar across the period.

Explain how successive IONISATION ENERGIES in Aluminium & Magnesium (Period 3) give evidence for SUB-LEVELS [3]?

• Al's outer electron is in the 3p1 sub-shell, while Mg's outer electron is in the 3s2 sub-shell.

• Al's outer electron is easier to remove than Mg's as it is further from the nucleus.

• This shows that electrons in the same energy levels don't have the same energies - due to the sub-levels.

Explain how successive IONISATION ENERGIES in Sulfur & Phosphorus (Period 3) give evidence for SUB-LEVELS [3]?

• S has 2 sets of paired electrons in its 3p orbital, while P has 1.5 sets of paired electrons in its 3p orbital.

• Removing an electron from a pair of electrons requires less energy compared to removing a singular electron.

• This is because of the negative charges repelling eachother.

Explain how successive IONISATION ENERGIES in Period 3 give evidence for SHELLS [2]?

• When you remove electrons one by one there is a big jump in ionisation energies.

• This is due to the electron being removed from an inner shell. This proves shells.

Explain how successive IONISATION ENERGIES in Group 2's GENERAL TREND give evidence for electron configuration [2]?

• Ionisation energy decreases as you go down the group.

• This is due to there being more shielding, so the electrons are further from the nucleus.

Explain how successive IONISATION ENERGIES in Group 2 give evidence for SHELLS [3]?

• Each element shows 2 small ionisation energies, then one big ionisation energy.

• This is due to the next electron being in an inner shell.

• This proves that group 2 elements have an outter shell of 2 electrons.

What is the definition for RELATIVE ATOMIC MASS? And how do you calculate this?

The average mass of an atom compared to 1/12th of a carbon 12 atom.

(isotope mass x relative abundance) + (other isotopes) DIVIDED BY the total relative abundance (100)

What are the 5 steps of the TIME OF FLIGHT MASS SPECTROMETRY?

• Ionisation - the sample is turned to gaseous ions.

• Acceleration - ions are accelerated by an electric field.

• Ion drift - ions are led through a flight tube to a detector.

• Ion detection - when ions hit the detector a current is produced, the time of arrival and intensity is measured.

• Data analysis - a mass spectrun is produced.

What are the 2 process for IONISATION?

• Electron impact →electron gun fires high energy electrons at a sample, this knocks off an electron. (This can lead to fragmentation).

• Electrospray → the sample is disolved in a solvent, injected in a hypodermic needle, the high voltage tip makes the atom gain a proton and leave the needle as a fine mist.

What are the equations linked to TOF MASS SPECTROMETRY [3]?

• KE = ½ x m x v²

• t = {the square root of:} m/z

• t = d x m/2KE

What information does the MASS SPECTRUM produce [2]? Explain how the relative atomic mass of an element can be calculated?

• y-axis = abundance

• x-axis = mass/charge

• multiply the abundance & m/z.

• sum the values.

• divide by the sum of abundances.