Unit 1 Flashcards
First ionisation energy
the energy required to remove one mole of electrons from one mole of gaseous atoms
What type of reaction is ionisation energy
endothermic (positive) as it requires energy to break electrostatic attraction.
Trend in ionisation energy across the period
increases- increased nuclear charge, more energy required to remove electrons.
trend in ionisation energy down a group
decreases- increasing electron shells, inner shells shield outer shells from nuclear charge meaning less energy required to remove electron.
Why might the second ionisition energy of an atom be much higher than the first?
because an electron is being removed from a full, stable shell that is closer to the nucleus
Definition of covalent radii
half the distance between the nuclei of two covalenty bonded atoms
Trend in covalent radii across the period
decrease- increasing nuclear charge which pulls electron shells more closer to the nucleus
Trend in covalent radii down a group
increases- increasing electron shells
Definition of electronegativity
the measure of attraction an atom involved in a bond has for the electrons in that bond
Trend in electronegativity across the period
increases- nuclear charge increases which creates a stronger electrostatic attraction, electrons held more tightly
Trend in electronegativity down a group
decreases- increasing electron shells. inner shells shield outer shells from nuclear charge, electrons further from nucleus
What is metalic bonding?
positive metal ions surrounded by a sea of delocalised electrons
What are the properties of metalic bonding?
- lattice= hight mp and bp.
- can conduct due to delocalised electrons
What is covalent bonding?
shared pair of electrons between atoms.
What are the properties of covalent molecular bonding?
- discrete= low mp and bp
- weak intermolecular forces
- doesn’t conduct