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What is meant by the term "atomic number"? Explain what it tells us about an element and why it is important in science.

The atomic number is a very important concept as it helps us understand the structure and identity of elements.

Definition of Atomic Number:

The atomic number of an atom is the number of protons found in the nucleus of that atom.

It is usually represented by the letter Z.

Why the Atomic Number is Important:

1. Identifies the Element:

Each element on the Periodic Table has a unique atomic number.

This means no two different elements can have the same number of protons.

For example, hydrogen has an atomic number of 1 (it has 1 proton), while carbon has an atomic number of 6 (6 protons).

2. Determines Position on the Periodic Table:

The elements in the Periodic Table are arranged in order of increasing atomic number.

This arrangement helps us see patterns in how elements behave.

3. Tells the Number of Electrons in a Neutral Atom:

In a neutral atom, the number of electrons is equal to the number of protons.

So, the atomic number also tells us how many electrons an atom has, which affects its chemical properties.

Extra Notes:

If an atom gains or loses electrons, it becomes an ion, but the atomic number never changes unless the element itself changes.

Changing the number of protons would mean changing the element entirely, which is why the atomic number is used to define an element.