Chemistry Module 2 Explanations

Pressure = Pascals Volume = m^3 n = mol Temperature = Kelvin (C+273)

• Reactivity increases down group • Atomic radii increase (there are more shells) • There is more shielding • Nuclear attraction decreases (increased shielding and distance outweigh increased nuclear charge) • Easier to remove outer electrons 6.Ionisation energy decreases

• Reactivity decreases down group • Atomic radii increase (there are more shells) • There is more shielding • Nuclear attraction decreases (increased shielding and distance outweigh increased nuclear charge) • Harder to attract outer electrons • Ionisation energy increases

Bleach

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In solid state H2O molecules are held apart by hydrogen bonds (it has an open lattice structure)

(Relatively strong) hydrogen bonds need to be broken. A lot of energy is needed to overcome these.

High melting boiling point Due to strong covalent bonds (sigma bonds) between atoms that require large amts of energy to overcome

High melting/ boiling point Due to strong electrostatic attraction between ions

• Metals have a giant structure • There is metallic bonding, with positive ions and delocalised electrons • There is electrostatic attraction between positive ions and electrons

• Though atoms within molecules bonded strongly, molecules are held together by weak intermolecular forces • Intermolecular forces/van der Waals forces don’t need a lot of energy to overcome Only the intermolecular forces are overcome during melting and boiling, not the covalent bonds

Poor conductivity regardless of state Due to no ions being presetn Can’t carry charge

When solid, poor conductivity Due to ions being held in place by lattice structure, so ions aren’t free to move When molten or aqueous, high conductivity Due to ions being free to move

High conductivity due to structure Electrons are delocalised, so are free to carry charge

No mobile charged particles: simple molecules never conduct electricity

• Electrons in an atom/molecule are constantly moving • A temporary uneven distribution of electrons occurs for an instant: an instantaneous dipole 3.The instantaneous dipole induces a dipole in its neighbours • Leads to attraction

1.Non-polar molecules only have London forces between molecules 2. As molecules get larger, the number of electrons increases 3. Size of the induced dipoles also get larger, giving stronger forces

Particles are in random motion Collisions between particles are elastic Particles have negligible size There are no intermolecular forces

Reaction may not have gone to completion Other reactions may have taken place simultaneously Purification may result in loss of product

Find the concentration of a solution Test the purity of a substance Identify an unknown chemical

Ionic compounds are soluble in polar solvents