3.4 The structure of atoms

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The Structure of Atoms

The three possible particles in an atom

Protons: give the atom its atomic number, the atomic number is the amount of protons, a proton is positively charged.

Neutrons, these together with the amount of protons give the atomic mass. A neutron has no charge

Electrons: are flying around the core in orbitals, are the same amount as the protons and are negatively charged.

Isotopes

Each element has an atomic number = number of protons.

Each atom has a mass number = number of protons + neutrons.

The number of neutrons can differ.

Then we have the same element (type of atom)
but with different mass numbers.

We call these isotopes.

How to find which atom something is

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Which atom is this?

Which atom is this?

Iodine has an isotope with 127 particles in its core.
This isotope has 53 protons and 74 neutrons.

How many electrons does this isotope of iodine have?

1. 21
2. 53
3. 74
4. 127

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