Periodic table trend definitions

Question 1

Atomic radius

Answer 1

Distance from the nucleus to the boundary of electrons. Atomic radius decreases as core charge increases. Increased electrostatic attraction pulls electrons closer.

Question 2

Ionisation energy

Answer 2

The amount of energy needed to remove one electron from an atom in the gas phase. Ionisation energy increases as core charge increases because more energy is needed to overcome the attractive electrostatic force between an electron and the nucleus.

Question 3

Electronegativity

Answer 3

The tendency of an atom to attract a bonding pair of electrons. Core charge increases across a period so electrons are more attracted to the nucleus going across a period. As the radius gets smaller, electrons can move closer to the nucleus so attraction is stronger.

Question 4

Electron affinity

Answer 4

The ability of an atom in a gas state to accept an electron from a negative ion. An atom will be more willing to accept an electron if it has more protons, and if the atomic radius is small enough for the electron to move closer to the nucleus.

Question 5

Metallic character

Answer 5

A measure of how much an atom behaves like a metal (chemical and physical properties). Metallic character increases when the attraction between valence electrons and the nucleus is weaker, enabling an easier loss of electrons. Decrease across the periodic table because as core charge increases, electrostatic attraction increases.

Question 6

Core charge

Answer 6

A measure of attraction between the valence electrons and the nucleus of an atom. Core charge = proton number - inner shell electrons