Chapter 7 Flashcards
Definition of first ionisation energy.
The energy required to remove one electron from each atom in one mole of gaseous atoms of an element.
What are the three factors affecting ionisation energies.
Atomic radius (further away, weaker attraction), nuclear charge (more protons, increased attraction), inner shell shielding (inner shell electrons repel outer shell electrons - causes shielding affect, decreased attraction)
Why do first ionisation energies decrease down a group?
Radius increases, more inner shell shielding as more inner shells, so nuclear attraction decreases.
What is the link between ionisation energies and no.electrons.
An element has as many ionisation energies as it has electrons.
Why is the 2nd ionisation energy greater than the 1st?
After first electron is lost, the 2nd will be removed from a positive ion where electrons have been pulled closer to nucleus. Nuclear attraction increases so more energy needed.
Definition of metallic bonding.
The strong electrostatic attraction between metal cations and delocalised electrons.
What are three properties of metals?
High electrical conductivity (solid & molten) as electrons free to move. High melting/boiling points (depend on strength of metallic bond), insoluble
Describe the structure of a metal.
It is a giant metallic lattice held together by metallic bonds.
What are two properties of simple molecular structures?
Strong covalent bonds, weak intermolecular forces so low melting/boiling points.
Describe the structure of diamond.
Carbon forms 4 bonds to another carbon. Tetrahedral arrangement 109.5•. Very strong covalent bonds, insoluble, do not conduct electricity, high melting/boiling points.
Describe the structure of graphite.
Carbon forms 3 covalent bonds bonds, trigonal planar. Has delocalised electrons resulting in planar hexagonal layers held by weak London forces. High m/b points, insoluble, electrical conductor
Describe the structure of graphene.
Single layer of graphite, strong and thin, electrical conductor
