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Activity 5.9
1. Examine third-period elements and classify them as metals and non-metals.
The third-period elements are sodium (Na), magnesium (Mg), aluminium (Al), silicon (Si), phosphorus (P), sulphur (S), chlorine (Cl), and argon (Ar).
Metals | Sodium (Na), Magnesium (Mg), Aluminium (Al) |
Non-metals | Phosphorous (P), Sulphur (S), Chlorine (Cl), Argon (Ar) |
Metalloid | Silicon (Si) |
Note: Argon (Ar) is an inert gas that is classified as non-metal.
2. Metals are found on which side of the periodic table?
Metals are found on the periodic table's left side.
3. Non-metals are found on which side of the periodic table?
Non-metals are found on the periodic table's right side.
As we can notice, metals like Na and Mg are on the left side of the periodic table, while non-metals like Sulphur and Chlorine are on the right. We have Silicon in the middle, classified as a semi-metal or metalloid because it has properties similar to both metals and non-metals.

Metals and non-metals are separated in the modern periodic table by a zig-zag line. The borderline elements with intermediate properties, such as boron, silicon, germanium, arsenic, antimony, tellurium, and polonium, are metalloids or semi-metals.
As you can see in Chapter \(3\) (Metals and Non-metals), metals are electropositive in nature because they prefer to lose electrons while forming bonds.