Answer: Mg has 2 valence electrons (after removing 2, the 3rd comes from a noble gas core).
- A Mg has 2 valence electrons (after removing 2, the 3rd comes from a noble gas core)
- B Mg actually has 3 valence electrons available for removal
- C The third electron occupies a higher principal energy level than the first two
- D Mg behaves as a transition metal with variable oxidation states
Correct answer: A. Mg has 2 valence electrons (after removing 2, the 3rd comes from a noble gas core)
Explanation: After removing 2 valence electrons, the 3rd must come from the filled 2p<sup>6</sup> shell (noble gas core), requiring much more energy.
The complete modern periodic table (118 elements). Image: Cepheus et al., Public Domain, via Wikimedia Commons.
Concept context
The periodic table organises all 118 elements by atomic number and similar properties. Study periodic trends like atomic radius, ionization energy, and electronegativity, and learn how an element's position predicts its behaviour.
Read the full Classification of Elements and Periodicity in Properties notes →