Periodic/Reactivity/Size Tends & Concepts

Period

Horizontal row with elements in a periodic table,

Groups

Vertical columns of elements that share the same properties in the periodic table.

Valence Electrons

Electrons are found in an atom's outermost occupied energy level. ( Often the same as the groups number last digit. except Helium. Contribute to an element’s reactivity)

Period Number Trend

The number of the period equals the number of energy levels or shells an atom has.

Group Number Trend

All elements in the same group have the same number of valence electrons.

Atomic Size: Down a Group

Increases the number of shells. The more shells an atom has, the easier it is to take away and the more reactive it’ll be.

Atomic Size: Across a Period

Going left to right the number of protons increases in periodic table. Attraction between electrons and protons are stronger which pulls the electrons closer.

Metal Reactivity Trend

Becomes more reactive as the atom gets bigger (down a group).

Non-Metal Reactivity Trend

Becomes more reactive as they get smaller (up a group).

Metal Reactivity Why?

Metal loses electrons. Electrons are further away in bigger atoms and can be taken away more easily.

Non-Metal Reactivity Why?

Non-metals take electrons. So the smaller it is, the stronger the force of attraction is between the nucleus and the valence shell

Most Reactive Metal

Francium (Group 1) is the most reactive

Most Reactive Non-Metal

Fluorine is the most reactive

Alkali Metals Reactivity

Reactivity increases down a group to the left.

Halogens Reactivity

Reactivity increases up a group to the right.