Atomic structure

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because they have the same number of electrons in their outer shells

amount of energy required to remove one mole of electrons from one mole of gaseous atoms of an element to form one mole of gaseous ions

energy required to remove one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions

X2+ (g) → X3+ (g) + e-

because once you have removed the outer electron from an atom, you have formed a positive ion Removing an electron from a positive ion is more difficult than from a neutral atom As more electrons are removed, the attractive forces increase due to decreasing shielding and an increase in the proton to electron ratio

with increasing shell number

elements across the periods show repeating patterns in chemical and physical properties

In the plum pudding model, atoms were described as being made from electrons embedded within a positive sphere, whereas in the nuclear model the nucleus is a positive structure at the centre of the atom, with negative (and much smaller) electrons ‘orbiting’ around the outside of it

relative atomic mass: mean mass of an atom of an element relative to 1/12 of the mean mass of an atom of the carbon 12 isotope relative isotopic mass: isotopic mass of an isotope relative to 1/12 of the mean mass of an atom of the carbon 12 isotope

ionisation - a sample of an element is vaporised and injected into a mass spectrometer where high voltage is passed over the chamber causing electrons to be removed from the atoms resulting in a +1 charged ion acceleration - positively charged ions are accelerated towards negatively charged detection plate ion drift - ions are deflected by magnetic field into a curved path. This depends on the charge and mass of the ion. detection - when the positive ions hit negatively charged detection plate they gain an electron producing a flow of charge Analysis - current values used with combination of flight time to produce a spectra print out of the relative abundance of each isotope.

minimum energy required to remove one mole of electrons from one mole of atoms in gaseous state.

Along a Period - first ionisation energy increases due to a decreasing atomic radius and greater electrostatic forces of attraction. Down a Group - first ionisation energy decreases due to an increasing atomic radius and electron shielding which reduces the effect of the electrostatic forces of attraction.

lowest energy orbital is filled first electrons with same spin fill up an orbital before pairing no more than 3 electrons

if electron spins are unpaired they are therefore unbalanced producing natural repulsion between the electrons making the atom very unstable

when elements across the periods show repeating patterns in chemical and physical properties

energy required to remove one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions

s : one orbital (1 x 2 = total of 2 electrons) p : three orbitals ( 3 x 2 = total of 6 electrons) d : five orbitals (5 x 2 = total of 10 electrons) f : seven orbitals (7 x 2 = total of 14 electrons)

He more protons than H / He greater nuclear charge than H (1) in helium the outer electron is in the same shell as hydrogen (1) H > Li: * in lithium the outer electron is in a higher energy level / a new shell / further from the nucleus / in a 2s orbital • (and) is shielded by inner electrons / 1s? electrons

the same number of protons is attracting a decreasing number of electrons electron is removed from an increasingly positively charged

(the electron being removed from E) is from a new subshell / p-subshell / p-orbital (1) which is more shielded from the nucleus than the s-subshell (from which the electron is removed in D) OR * which is further from the nucleus than the s-subshell / orbital

Alkali metals always have the lowest first ionization energy in their period Ionization energy falls (significantly) at the start of a (new) period