IB SL Chemistry- Structure 3.1

True or False: Periods of the periodic table are horizontal.

True

True or False: Groups of the periodic table are vertical.

True

What types of bonds can metalloids form?

Both ionic and covalent bonds.

Principal Quantum Number, n

Corresponds to the outermost electron sublevels for elements in that period number.

Periodicity

The study of trends in the periodic table.

Atomic Radius trend + reason

Decreases from left to right because there is an increased nuclear charge going across a period meaning there is a greater attraction between valance electrons an the nucleus.

Increases up and down a group because a higher energy level is added going down a group.

Effective Nuclear Charge, Z_eff

The diminished electrostatic force experienced by a shielded valence electron.

True or False: Z_eff is greater for cations.

True

True or False: The cation ionic radius is smaller than the atomic radius.

True

Ionic Radius trend + reason

The larger positive charge, the smaller radii. So, radius decreases across groups 1, 2 and 13.

The larger negative charge, the bigger radii. So, radius increases across groups 15, 16 and 17.

However, going down a group, ionic radius increases for both cations and anions because of the increasing number of electron energy levels and increased shielding of the nucleus.

True or False: The anion ionic radius is greater than the atomic radius.

Isoelectronic

Species that have the same electron configuration.

Ionization Energy (IE) definition

The minimum energy required to eject an electron out of a neutral atom or molecule in its ground state.

Ionization Energy trend + reason

Generally decreases down a group because the number of energy levels increases and the shielding effect becomes greater, so less energy is required to ionize atoms.

Generally increases across a group because of its increased nuclear charge.

Electron Affinity (EA) definition

The energy released when an additional electron is attached to a neutral atom or molecule.

Electron Affinity trend + reason

Generally increases going across a period as nuclear charge increases so more energy is released when an electron is added.

No clear trend going down a group.

Electronegativity definition

A measure of an atom’s ability to attract electrons from a chemical bond to itself.

Electronegativity trend + reason

Decreases down a group, and increases across a period. This is because smaller atoms with nearly complete valance shells will attract electrons more easily than larger atoms with fewer valence electrons.

True or False: Elements with a lower IE are more likely to have metallic character.

True because metallic character has delocalized electrons in its structure.

True or False: Halogens are more reactive higher up their group.

True because higher up in group 17 its elements have a higher electronegativity value and have a greater tendency to accept an electron to fill their valance shell.

True or False: Alkali metals are more reactive going down their group.

True because they have increasing metallic character going down the group meaning that there is a greater tendency for them to donate their single valence electron.

Bronsted-Lowry acid

A substance that donates protons, H⁺.

Bronsted-Lowry base

A substance that accepts protons, H⁺.

Lewis acid

Can accept an electron pair.

Lewis base

Can donate an electron pair.

True or False: Going across a period, the oxides of the elements become less basic and more acidic.

True

Amphoteric

A chemical species that behaves as both a Lewis acid and Lewis base.

Oxyanions

Polyatomic anions that include oxygen atoms.