(CHEM) Topic 3 - Periodicity

Define atomic radius

Distance from nucleus to the outermost electron

Trend in atomic radius down a group

Increasing — electron in higher energy level is further from the nucleus

Define ionic radius

Distance from the nucleus of an ion to the outermost electron of the ion

Define electronegativity

Ability of an ion to attract pairs of bonded electrons

Define first ionization energy

Energy required to remove one electron from an atom in gaseous state

Define electron affinity

Energy change when an electron is added to an atom in gaseous state

Effective nuclear charge (Z_eff) calculation

Number of protons minus number of shielding electrons

Trend in ionic radius down a group

Increasing — electron in higher energy level is further away from the nucelus

Trend in electronegativity down a group

Decreasing — extra energy level, more shielding effect

Trend in first ionization energy down a group

Decreasing — outermost electron is further from nucleus, less energy needed to remove it

Trend in electron affinity down a group

Decreasing — (less negative/exothermic) increasing shileding effect, electrons attrated less

Trend in atomic radius across a period

Decreasing — more protons, more nuclear charge, more attraction of valance electrons

Trend in ionic radius across a period

Decreasing — more protons, more nuclear charge, more attraction of valance electrons

Trend in electronegativity across a period

Increasing — increasing nuclear charge (extra electrons insignificant because they fill the same energy level)

Trend in first ionization energy across a period

Increasing — increasing nuclear charge (extra electrons insignificant because they fill the same energy level)

Trend in electron affinity across a period

Increasing — (more negative/exothermic) increasing nuclear charge

Trend in metallic character down group 1 (alkali metals)

Increasing

Trend in non-metallic character down group 17 (halogens)

Decreasing

Trend in reactivity down group 1 (alkali metals)

Increasing

Trend in reactivity down group 17 (halogens)

Decreasing

Electron configuration of bromine

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁵

Condensed electron configuration of copper

[Ar] 4s¹3d¹⁰

Condensed electron configuration of cobalt

[Ar] 3d⁷4s²

pH of metal oxides

Basic

pH of metalliods

Amphoteric

pH of non-metal oxides

Acidic

Main gasses resposible for acid rain

SO₂, NO_x

Atmospheric gas causing ocean acidification

CO₂