Chemistry 9476

[Atomic structure]

Behaviour of beams of protons, neutrons and electrons in electric fields.

How to determine extent of deflection?

Protons (+) deflect towards (-) field

Neutrons do not deflect to any fields

Electrons (-) deflect towards (+) field

Extent of deflection:

[Atomic structure]

What are isotopes?

Atoms of the same element with different numbers of neutrons, hence different mass

[Atomic structure]

Number & relative energy of s, p & d orbitals for principle quantum numbers 1, 2 and 3, as well as 4s & 4p orbitals

S — 1s, 2s, 3s, 4s (2 electrons)

• lowest energy in its respective quantum numbers

p — 2p, 3p, 4p (6 electrons)

d — 3d (10 electrons = break octet structure)

• highest energy in its respective quantum numbers

*4s —> must be filled first (lower energy than 3d when unfilled) & removed from first

[Atomic structure]

Shape of s, p & d orbitals

[Atomic structure]

Factors affecting ionisation energy of elements

Nuclear charge

• Total sum of positive charge in the nucleus of the atom

Electron shielding effect

• Repulsion of outer electron shells by inner shells

Effective nuclear charge

• Net amount of attraction between electrons and protons in the nucleus

[Chemical bonding]

Describe:

• Ionic bonding

• Covalent bonding

• Metallic bonding

• Strong electrostatic forces of attraction between oppositely charged ions in a giant ionic lattice structure

• Electrostatic attraction between a shared pair of electrons & positively charged nuclei

• Strong electrostatic forces of attraction between cations & sea of delocalised electrons in a giant metallic lattice structure

[Chemical bonding]

What are the types of s & p orbital overlaps in covalent bonding

π: head-on overlap over the axis with electron density concentrated between the nucleus — must have only 1 per bond

σ: 2-p orbitals overlap side-on (not along axis) with electron density concentrated above & below axis — multiple per bond

[Chemical bonding]

Definition of Valence Shell Electron Pair Repulsion Theory (VSEPR theory)

Electron pairs around central atom arranges themselves as far as possible to minimise repulsion — determines shape of molecules

Lone pair-lone pair > lone pair- bond pair > bond pair- bond pair

[Chemical bonding]

Shape & angle of 2 bond pair (e.g. CO₂)

CO₂: 2 bond pair, 0 lone pair around central atom C (angle 180)

[Chemical bonding]

Shape & angle of 3 pair (e.g BF₃ SO₂)

BF₃ : 3 bond pair, 0 lone pair around central atom B (angle 120)

SO₂: 2 bond pair, 1 lone pair around central atom S (angle 119)

[Chemical bonding]

Shape & angle of 4 pair (e.g. CH₄, NH₃, H₂O)

CH₄: 4 bond pair, 0 lone pair around central atom C (angle 109.5)

NH₃: 3 bond pair, 1 lone pair around central atom N (angle 107)

H₂O: 2 bond pair, 2 lone pair around central atom O (angle 104.5)

[Chemical Bonding]

Shape & structure of 5 pair

Shape & structure of 6 pair (e.g. SF₆)

SF₆: 6 bond pair, 0 lone pair around central atom S (angle 90)

[Chemical bonding]

How to determine bond polarity & its definition

It is a measure of how equally electrons are shared between 2 bonded atoms, heavily dependent on difference in electronegativity

• Polar: different electronegativity —> bonding electrons not shared equally (net dipole ≠ 0)

• Non-polar: same electronegativity —> bonding electrons shared equally (net dipole = 0)