Which elements above will form cations? List them below. a) Lithium b) sodium c) beryllium d) aluminum e) phosphorus f) oxygen g) fluorine
The correct answer and explanation is:
The elements that will form cations from the list are:
- a) Lithium (Li)
- b) Sodium (Na)
- c) Beryllium (Be)
- d) Aluminum (Al)
Explanation:
A cation is a positively charged ion, which forms when an atom loses one or more electrons. Cations are typically formed by metals, as they have fewer valence electrons and tend to lose them easily to achieve a stable electron configuration.
- Lithium (Li): Lithium is an alkali metal in Group 1 of the periodic table. It has one electron in its outermost shell. To achieve the stable electron configuration of helium, lithium loses this single electron, resulting in a +1 cation (Li⁺).
- Sodium (Na): Sodium is also an alkali metal, found in Group 1 of the periodic table. It has one valence electron, which it readily loses to form a +1 cation (Na⁺), similar to lithium. By losing this electron, sodium attains the stable electron configuration of neon.
- Beryllium (Be): Beryllium is an alkaline earth metal in Group 2. It has two valence electrons, which it loses to form a +2 cation (Be²⁺). Losing these two electrons gives beryllium the stable electron configuration of helium.
- Aluminum (Al): Aluminum is a metal in Group 13 of the periodic table with three valence electrons. It will lose all three electrons to form a +3 cation (Al³⁺), achieving the electron configuration of neon.
On the other hand:
- Phosphorus (P), Oxygen (O), and Fluorine (F) are nonmetals and typically form anions (negative ions) rather than cations. These elements tend to gain electrons to achieve a stable electron configuration (typically of the nearest noble gas), resulting in negative charges (e.g., P³⁻, O²⁻, F⁻).
Thus, only lithium, sodium, beryllium, and aluminum will form cations.