Trends In The Periodic Table Flashcards
What is meant by the term Covalent radius?
Covalent radius is half the distance between the nuclei of two bonded atoms.
What happens to the covalent radius as you go across the period?
The covalent radius decreases as you across the period because:
• The nuclear charge increases but the number of filled electron shells remains the same.
• An increase in the nuclear charge results in electrons being more strongly attracted to the nucleus which means that the covalent radius decreases.
What happens to the covalent radius as you go down the group?
The covalent readies increase as you go down the group because:
• There are more energy levels of electrons.
• Each extra layer of electrons “screen” the outer electrons from the positive nucleus so that the outer electrons are less strongly attracted to the nucleus.
• This results in an increase in covalent radius.
What is meant by the term Electronegativity?
Electronegativity is a measure of attraction an atom of an element has for bonding electrons.
What happens to the electronegativity as you go across the period?
Electronegativity increases across the period because:
• The nuclear charge increases which causes the atom to attract bonded electrons more strongly.
• Consequently, the Electronegativity increases across period.
What happens to the electronegativity as you go down the group?
The electronegativity decrease as you go down the group because:
• The number of filled electron shells increases.
• These extra electron shells screen the bonded electrons from the nuclear charge which means that electrons are less strongly attracted to the atom.
• Consequently, Electronegativity decreases going down the group.
What is meant by the term Ionisation energy?
Ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous atoms.
What happens to the ionisation energy as you go across the period?
The ionisation energy increases as you go across the period because:
• The nuclear charge is increasing.
• The outermost electrons are therefore more strongly held and so the energy required to remove them increases along each period.
• Consequently, the ionisation energy increases across period.
What happens to the ionisation energy as you go down the group?
The ionisation energy decreases as you go down the group because:
• An electron is being removed from the layer of electrons which is furthest from the nucleus.
• This layer is increasingly distant from the nuclear attraction, so less energy is required to remove an electron.
• The screening effect of electrons in inner shells reduce the attraction of the nucleus for outermost electrons, hence decreasing the ionisation energy.
