Structure 3.1

1/2 the distance between the nuclei of two bonded atoms

Increases due to increasing energy levels, electrons further away from the nucleus Same shielding

decreases same energy level and shielding increase in nuclear charge

the energy released when 1mol of electrons is attached to 1 mol of neutral atoms or molecules in the gas phase always negative, as atoms lose energy in the exothermic process of adding an electron

the more negative it is, the greater is the attraction of the ion for the electron

• attractive force of nucleus for the valence electrons - number of protons • in which energy level the valence electrons are • shielding of nuclear attraction by electrons

down a group - increases across a period - decreases

down a group - decreases across a period - increases

down a group - decreasing across a period - increasing

down a group - decreases across a period - increases

cations are smaller than anions, the opposite being true only for extremities of the periodic table

Ionisation energy is the energy required to remove the outermost electron from a species

the minimum energy required to lose one mole of electrons from one mole of gaseous atoms in the ground state

Decreases: Atomic radii increases, electrons occupy higher energy levels Leads to a weaker attraction to the nucleus Less energy required to remove an electron

Increases: Nuclear charge increases (there are more protons) and the atomic radius decreases More energy is required to remove an electron

nuclear charge and atomic radius the greater the nuclear charge and the smaller the atomic radius, the higher the ionisation energy

amount of energy released when a neutral atom gains an electron to form a negatively charged ion

Decreases going down a group Elements increase their atomic radius, and outer valence shells are further away from the nucleus Weaker attraction between the added electron and the nucleus

increases Elements across the period have a higher effective nuclear charge Stronger attraction between the added electron and the nucleus

the tendency of an atom to attract a shared pair of electrons in a covalent bond

decrease down a group atomic radius increases due to additional energy levels Weaker attraction between the nucleus and the shared pair of electrons

increase Effective nuclear charge increases Stronger attraction between the nucleus and the shared pair of electrons

metallic: the tendency of an element to lose electrons to form positive ions, lower ionisation energy non-metallic: tendency of an element to gain electrons, higher electron affinity

Increasing reactivity going down group 1 Elements have lower 1st ionisation energies, due to an additional energy level Easier for with lower ionisation energy to transfer the outer valence electron to water increasing reactivity with water.