How small is the nucleus?
The nucleus is about 10⁵ times smaller than the atom.
A speck in a stadium
An atom is already too small to see. Its nucleus is far smaller still.
About how many times smaller than the atom is its nucleus?
What this lesson covers
The idea
The nucleus is about 10⁵ times smaller than the atom: an atom's diameter is about 10⁻¹⁰ m and the nucleus's diameter about 10⁻¹⁵ m.
A speck in a stadium
An atom is already too small to see. Its nucleus is far smaller still.
About how many times smaller than the atom is its nucleus?
- About 10⁵ times (one lakh)
- About 10 times
- About 2 times
Set the size of the nucleus
The atom's diameter is about 10⁻¹⁰ m. Set the power of ten for the nucleus. The red dot is drawn far too big, so you can see it.
One lakh times smaller
The diameter of an atom is about 10⁻¹⁰ m and the diameter of its nucleus about 10⁻¹⁵ m. Their ratio is 10⁵, which is one lakh. If an atom were a cricket ground about 100 m across, the nucleus would be a tiny black pepper grain at the centre.
The nucleus is about 10⁵ times smaller than the atom: an atom's diameter is about 10⁻¹⁰ m and the nucleus's diameter about 10⁻¹⁵ m.
Notes
The nucleus is about 10⁵ times smaller than the atom: atom about 10⁻¹⁰ m, nucleus about 10⁻¹⁵ m.
Check yourself
The atom's diameter is about 10⁻¹⁰ m and the nucleus's about 10⁻¹⁵ m. The atom is how many times wider? Write the whole number.
Answer: 100000
10⁻¹⁰ ÷ 10⁻¹⁵ = 10⁵ = 100000, which is one lakh.
If an atom were the size of a cricket ground, what would the nucleus be like?
The diameter of the nucleus is about …
- A tiny black pepper grain at the centre — correct. Yes!
- A football at the centre. The nucleus is about one lakh times smaller than the atom, far smaller than a football.
- Half the cricket ground. Most of the atom is empty space and the nucleus is extremely small.
- 10⁻¹⁰ m. That is about the diameter of the whole atom.
- 10⁻¹⁵ m — correct. Yes!
- 10⁵ m. 10⁵ is the number of times the nucleus is smaller than the atom, not its diameter in metres.