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13 terms

LC Chem 2.3 Trends in the Periodic Table

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Nuclear charge
The total charge of all the protons in the nucleus.
Atomic radius
Half the distance between the nuclei of 2 atoms of the same element joined by a single covalent bond
Increase (in atomic radius)
Trend in atomic radii DOWN a group due to addition of a new shell and the screening effect of inner electrons
Decrease (in atomic radius)
Trend in atomic radii ACROSS a period due to increasing nuclear charge but no increase in the screening effect
First ionisation energy
The minimum energy required to completely remove the most loosely bound electron in its ground state from a mole of neutral gaseous atoms.
Decrease (in ionisation energy)
Trend in ionisation energy DOWN a group due to increasing atomic radius and the screening effect of inner electrons.
Increase (in ionisation energy)
Trend in ionisation energies ACROSS a period due to increasing nuclear charge and decreasing atomic radius.
Electronegativity
The relative attraction that an atom in a molecule has for the shared pair of electrons in a covalent bond.
Decrease (in electronegativity)
Trend in electronegativity DOWN a group due to increasing atomic radius and the screening effect of inner electrons
Increase (in electronegativity)
Trend in electronegativity ACROSS a period due to increasing nuclear charge and decreasing atomic radius.
Decrease (in halogens)
Trend in the reactivity of the halogens DOWN the group due to the decrease in electronegativity values.
Increase (in alkali metals)
Trend in the reactivity of alkali metals DOWN the group due to the decrease in ionisation energy meaning the outer electron is more easily lost from the metal.
Increase (in boiling point)
Trend in the boiling points of the noble gases and the halogens DOWN the group due to the increase in the van der Waals forces between the individual molecules due to the increasing size of the atoms.