Idk Flashcards
(62 cards)
Ionic bonding
Square
Electrostatic attraction between oppositely charged ions
Covalent
Circles joined
Electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
Polar
Difference in electronegativity, dipoles dont cancel out
How London forces appear
Electrons in an atom are constantly moving
Electrons can become unevenly distributed, creating a slightly negative charge
This creates a slightly positive charge in neighbouring molecule
Ionisation energy down groups
First ionisation energy decreases
Atomic radius increases
More inner shells so shielding increases
Nuclear attraction on outer electrons decreases
Ionisation energy across periods
First ionisation energy increases
Atomic radius decreases
Nuclear charge increases
Electrons on same shell so, similar shielding
Nuclear attraction increases
Ionisation energy across periods exception
Boron - single electron in 2p sub shell
Oxygen - electrons are paired in first p orbital. Electrons repel making it easier to lose the electron
Boron, carbon, silicon
Giant covalent lattices
Carbon
Each carbon atom forms 4 strong covalent bonds
Insoluble
Doesn’t conduct electricity
High MP&BP
Graphite
Each carbon atom forms 3 strong covalent bonds meaning, 1 delocalised electron
No bonds between layers so soft
Group 2
Ionisation energy decreases down group
Nuclear attraction decreases due to increasing atomic radius & increased shielding
Reactivity increases down group
Solubility & pH also increase
Group 7
Diatomic, BP increases down group due to stronger London forces
Reactivity decreases as less nuclear attraction so harder to gain electron
Chlorine - colour in solution, colour in cyclohexane, precipitate dissolves in
Pale green
Pale green
Dilute ammonia
Bromine - colour in solution, colour in cyclohexane, precipitate dissolves in
Orange
Orange
Concentration ammonia
Iodine - colour in solution, colour in cyclohexane, precipitate dissolves in
Brown
Violet
Doesn’t dissolve
Disproportionation
Element is simultaneously oxidised & reduced
Relative atomic mass
Weighted mean mass of an atom of an element compared to 1/12th of the mass of an atom of carbon-12
Two anomalous properties of ice caused by hydrogen bonding
Ice is less dense than water due to the hydrogen bonding creating an open lattice
Ice also has a higher melting & boiling point as it contains hydrogen bonding which requires more energy to overcome
Explain why successive ionisation energies always increase
As each electron is removed, the outer shell is drawn closer to the nucleus.
Nuclear attraction is greater and more energy is needed to remove the next electron
Explain why Al has a lower first ionisation energy than Mg
Explain why S has a lower first ionisation energy than P
3p subshell in Al has a higher energy level than the 3s subshell in Mg. 3p electron is easier to remove.
P has 3 electrons in 3p subshell, 1 electron in each 3p orbital. S has 4 electrons in 3p subshell, 2 electrons paired in 1 orbital and 1 electron in other 2 3p orbitals.
Paired electrons in sulfur repel one another making it easier to remove one of those electrons
Properties of ionic compounds
Giant ionic lattice
High M&BP as electrostatic force holding the ionic lattice together is strong & requires a lot of energy to overcome
Molten - can conduct electricity as there are mobile ions to carry a charge
Solid - ions in a fixed position.
Brittle - when the layers of alternating charges are distorted, like charges repel, breaking apart the lattice into fragments
Soluble - polar water molecules break down the lattice and surround each ion in solution
Electronegativity
Atoms ability to attract electrons towards itself in a covalent bond
Increases across a period as atomic radius decreases & nuclear charge increases
Decreases down a group as shielding increases and atomic radius increases so nuclear charge decreases
Simple molecular
Definite molecular formula, Non & non
Simple molecular lattice
Molecules are held in place by weak intermolecular forces
Atoms within each molecule are bonded together strongly by covalent bonds
Properties of simple molecular
Weak intermolecular forces broken by small amounts of energy
Low melting and boiling points
Covalent bonds don’t break when heated
No mobile particles to carry a charge
Insoluble in polar solvents
- intermolecular bonding within the polar solvent is too strong to be broken
