periodicity

• covalent radius - a measure of the size of an atom and is equal to half the distance between the nuclei of atoms joined by a covalent singular bond
• cov rad - as you go along a period, number of protons increase so greater nuclear charge that pulls the outer electrons in closer, creating a smaller covalent radius
• cov rad - as you go down a group, there is more electron shells so electrons will be further from the nucleus. inner shells create a 'shielding effect' which shields the outer electrons from the nuclear charge, making the electrons less tightly held in
• electronegativity - the attraction the nucleus has for its bonding electrons
• electroneg - as you go along a period there are more protons leading to a greater nuclear charge which pulls the outer electrons in closer. increase in nuclear charge causes greater attraction for bonding electrons = higher electronegativity.
• electroneg - as you go down a group there are more shells which means the outer electrons are further from the nucleus and inner shells 'shield' the outer electrons from the nuclear charge, so the nucleus is less attracted to them = lower electronegativity.
• ionisation energy - the energy required to remove 1 mole of electrons from one mole of gaseous atoms
• io - as you go along a period there is a greater nuclear charge which attracts and pulls the electrons in closer, so more energy is required to remove 1 electron
• io - there are more electron shells as you go down a group that shield outer electrons from the nuclear charge so they are less attracted and less energy is required to remove 1 electron