Inside the Atom
Meet protons, neutrons, and electrons
What this lesson covers
Why it matters
If you could shrink down to the size of an atom, you would find a tiny, dense nucleus surrounded by a vast, empty space where electrons zip around.
Predict first
Where is most of the atom's mass located?
The nucleus contains protons and neutrons, which are much heavier than electrons, concentrating almost all the mass in the center.
- In the electrons orbiting outside
- In the tiny, central nucleus — correct
- Evenly distributed throughout the sphere
What you do
Build a neutral carbon atom: 6 protons and 6 neutrons in the nucleus, and 6 electrons around it.
Check yourself
What determines the identity of an element?
The atomic number (Z) equals the number of protons. Change the proton count, and you change the element.
Why is an atom electrically neutral?
Protons carry +1 charge and electrons carry -1 charge. In a neutral atom, these counts are equal, resulting in a net charge of zero.
What is the charge of a neutron?
Neutrons have no electric charge, which is why they are called 'neutrons'.
- The number of neutrons
- The number of protons (Atomic Number) — correct
- The number of electrons
- The total mass of the atom
- Protons and neutrons cancel each other out
- The number of positive protons equals the number of negative electrons — correct
- Electrons are too small to have charge
- Positive (+1)
- Negative (-1)
- Neutral (0) — correct