Chemistry · Visual explanation
When an atom becomes an ion, what changes?
Count protons and electrons separately. The nucleus identifies the element.
The short answer
An atom becomes an ion when its electron count changes. Losing electrons produces a positive ion; gaining electrons produces a negative ion. The number of protons determines the element and is unchanged in ordinary ion formation.
Conceptual illustration. Colours distinguish parts of the model.
TRY A SMALL CHANGE
Predict first. Then move the control.
Where the confusion starts
A positive ion has not gained protons in a chemical reaction. It has fewer negatively charged electrons than positively charged protons. Changing the proton number would change the element; that is not ordinary chemical ion formation.
WORK IT THROUGH
A sodium atom has 11 protons and 11 electrons.
- The neutral atom has equal positive and negative charges.
- If it loses one electron, it has 11 protons and 10 electrons: a net charge of +1.
- It is still sodium. Write Na⁺. In this example the nucleus and its neutron count do not change.
CHECK YOUR UNDERSTANDING
A chlorine particle has 17 protons and 18 electrons. What is its charge?
Make a prediction or write an answer before opening the explanation.
Reveal the explanation
−1. There is one more electron than proton, so it is a chloride ion, Cl⁻. The element is still identified by its 17 protons.
SEE IT. CHANGE IT. EXPLAIN IT.
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