Aim: What are the Properties of Groups and how does the atomic radius change across

a period and down a group?DO Now:1. Write down the electron configuration and the

number of protons for Li, Na and Be.2. Compare the atomic radii of Li and Na, and Li

and Be. Which would have a larger atomic radius?

Periodic Trends

Many trends of elements can be explained by electron configuration and position on the periodic table

Trends to be examinedAtomic radiusIonic radiusIonization energyelectronegativity

Atomic Radius

The distance from the center of the nucleus to the outermost shell.

Atomic Radius- Down a Group: A Closer Look at Lithium and Sodium

As you move down a group or family the atomic radius increases due to more energy levels

Atomic Radius – Across a Period

Same number of energy levels, but Be has more protons pulling on the outer electrons, making Be smaller. As you move across a period, the atomic radius becomes smaller.

Which has the largest atomic radius?

ChlorineFluorine IodineBromine

Ionic Radius

The distance from the nucleus to the outermost electron of an ion.

An ion is an atom that has gained or lost electrons to have a full outer shell (8 electrons) like the noble gases.

Ionic Radius

Sodium – Atom

Sodium - Ion

Ionic Radius

The sodium ion loses the outer most electron to have a full outer shell. It is now smaller than the atom. It has one less electron making it have a +1 charge.

Ionic Radius

Some atoms gain electrons to have a full outer shell. The atom then takes on a negative charge and the ion is larger than the atom.

Metals tend to lose electrons while nonmetals tend to gain electrons.

For each set of elements select the one with the smallest radius and give a reason for your choice.

Set 1: C, N, O, FSet 2: F, CL, Br, ISet 3: Na, K, Na+, K+

Set 4: Na+, K+, Mg2+, Ca2+

Set 5: F, F-, Na, Na+