Outcomes 14-21 Structure 3

trends in ionization energy

ionization energy increases across a period and decreases across a group

Why does ionization energy increase across a period?

Nuclear charge increases and the atomic radius decreases across across a period so more energy so more energy is required to remove the outer electrons

Why does ionization energy decrease down a group

The number of occupied energy levels increases down a group, increasing the atomic radius, which means less energy is required to remove the outer electrons

First ionization energy

The energy required to remove one mole of electrons from one mole of gaseous atoms to produce one mole of gaseous ions

Atomic radius trend

increases down a group and decreases across a period

Ionic radius trend

increases down a group and decreases across a period

Electron affinity trend

decreases down a group and increases across a period

Electronegativy trend

decreases down a group and increases across a period

Explain group 1 alkali metals

They are very reactive and have a low ionization energy.

How do alkali metals react with water

The further down the group, the more vigorously they react. They produce hydrogen and metal hydroxide.

Describe group 17 halogens

They are coloured and very reactive non-metals. Their reactivity decreases down the group

What are the physical properties of transition metals?

They have a high melting point, are malleable and ductile, and are catalysts

Why are transition metals colored?

The 3d sublevel splits into 2 energy levels

Why would a transition metal be colorless?

If the 3d sublevel was empty or full

Why do transitional metals appear coloured?

They absorb visible light

Why do transition metals absorb light?

Because the d sublevel splits into 2 levels

Define atomic radius

The distance from the atom’s nucleus to the outer edge of the electron cloud

Define ionic radius

The distance between between the core atom and the outermost atom

Define electron affinity

the amount of energy released when an electron attaches to a neutral atom or molecule to form an anion

Define electronegativity

the tendency of an atom or a functional group to attract electrons toward itself.