C1 - Noble gases, Group 0

What are the Group 0 elements called?

The noble gases.

Why were noble gases not in Mendeleev's original periodic table?

Because they were not fully discovered until after Mendeleev developed his table.

Are noble gases reactive or unreactive?

Noble gases are very unreactive.

How many electrons does a helium atom have?

Two electrons.

Where are helium's electrons located?

Both electrons are in the first energy level.

What is the maximum number of electrons the first energy level can hold?

Two electrons.

Why is helium stable?

Because its first energy level is full with two electrons.

Why are atoms stable when they have a full outer energy level?

Because a full outer energy level means the atom is stable and unlikely to react.

How many electrons does a neon atom have?

Ten electrons.

How are neon's electrons arranged in energy levels?

Two electrons in the first energy level and eight electrons in the second energy level.

What is the maximum number of electrons the second energy level can hold?

Eight electrons.

Why is neon unreactive?

Because it has a full outer energy level with eight electrons.

How many electrons are in the outer energy level of argon?

Eight electrons.

Why is argon unreactive?

Because it has a full outer energy level.

What is the key reason all noble gases are unreactive?

They all have a full outer energy level.

What is the physical state of noble gases at room temperature?

They are all gases.

Why are noble gases gases at room temperature?

Because they have very low boiling points, all below room temperature.

How do the boiling points of noble gases change down the group?

The boiling points increase as you move down the group.

What causes the boiling points of noble gases to increase down the group?

The relative atomic mass increases, leading to stronger intermolecular forces.

Which noble gas has the lowest boiling point?

Helium.

Which noble gas has the highest boiling point?

Radon.