Why are the noble gases unreactive?

They have full outer shells of electrons. A full outer shell is a stable arrangement.

In what form do the noble gases exist?

single atoms. They are monatomic.

Which of these is a noble gas?

argon. Argon is in the last group of the Periodic Table.

Why is argon used to fill filament lamps?

It does not react with the hot filament. In air the hot filament would burn away.

The noble gases · Cambridge IGCSE Combined Science revision

In plain words

The noble gases are the elements that don't join in. Their atoms already have a full outer shell of electrons, which is what other atoms react to get. With nothing to gain, they stay as single atoms and react with almost nothing.

Three things to know

The noble gases (helium, neon, argon and the rest of the last group) are colourless gases that exist as single atoms.
They are unreactive because they have a full outer shell of electrons, so they do not need to gain, lose or share any.
Uses come from being unreactive: argon fills lamps, helium fills balloons.

Tips and tricks

"Unreactive because they have a full outer shell" answers nearly every noble gas question.
Link each use to that property: argon in lamps and helium in balloons are both chosen because they will not react.

5 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

The noble gases: 5 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

Why are the noble gases unreactive?
- They are gases.
- They have full outer shells of electrons. (the answer)
- They have no electrons.
- They are very light.
A full outer shell is a stable arrangement.
In what form do the noble gases exist?
- single atoms (the answer)
- molecules of two atoms
- giant structures
- ions
They are monatomic.
Which of these is a noble gas?
- nitrogen
- chlorine
- argon (the answer)
- hydrogen
Argon is in the last group of the Periodic Table.
How many electrons are in the outer shell of a neon atom (2,8)?
- 2
- 6
- 8 (the answer)
- 10
Its second shell is full.
Why is argon used to fill filament lamps?
- It glows brightly.
- It does not react with the hot filament. (the answer)
- It is a good conductor.
- It is cheap to make from water.
In air the hot filament would burn away.

5 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

3 questions, 5 marks. Write your answers on paper, then check them.

The noble gases

Cambridge IGCSE Combined Science 0653 · 5 marks · papermunch.org

Name ______________________________ Date ______________

Explain why the noble gases are unreactive.[2]
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Their atoms have full outer shells of electrons, so they have no tendency to gain, lose or share electrons.
I got this one
Explain why helium, not hydrogen, is used to fill balloons.[2]
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Both have a low density, but helium is unreactive, while hydrogen is flammable.
I got this one
State what is meant by monatomic.[1]
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Made of single atoms that are not bonded to each other.
I got this one

Answers: The noble gases

1. Their atoms have full outer shells of electrons, so they have no tendency to gain, lose or share electrons.
2. Both have a low density, but helium is unreactive, while hydrogen is flammable.
3. Made of single atoms that are not bonded to each other.