Common Misconceptions

⚠️ Common Misconceptions

Misconception 1: "All metals are solid at room temperature"

Mercury (Hg) is a metal that is liquid at room temperature — it has a melting point of -39°C. This is a favourite exam trick! When asked to identify metals on the periodic table, do not assume all metals are solids; their position (left/centre of table) is the reliable indicator, not their state.

Misconception 2: "Group 7 reactivity increases going down the group (like Group 1)"

This is the most common error when comparing groups. Group 1 reactivity increases going down because it gets easier to lose an electron. Group 7 reactivity decreases going down because it gets harder to gain an electron — the outer shell is further from the nucleus and less attractive to a new electron. The two groups show opposite trends.

Misconception 3: "Elements are arranged in the periodic table by atomic mass"

The modern periodic table (since Moseley's work in 1913) is arranged by atomic number (number of protons), not atomic mass. Mendeleev used mass and had to make awkward exceptions. Atomic number gives a perfect, unambiguous ordering with no exceptions needed.