Question

Of the elements \(\mathrm{Li}, \mathrm{Be}, \mathrm{N}\), and \(\mathrm{F}\), which a. is an alkaline earth metal? b. has the largest atomic radius? c. has the highest ionization energy? \(\mathbf{d}\). is found in Group \(5 \mathrm{~A}(15) ?\)

Short answer

a. Be, b. Li, c. F, d. N

Step-by-step solution

Identify Alkaline Earth Metal

Alkaline earth metals are elements in Group 2 of the periodic table. These elements are known to have two electrons in their outer shell.

Check Group 2 Elements

The elements provided are \(\text{Li}\), \(\text{Be}\), \(\text{N}\), and \(\text{F}\). From this list, \(\text{Be}\) (Beryllium) is the only element that is an alkaline earth metal.

Identify Largest Atomic Radius

Atomic radius generally increases down a group and decreases across a period. Therefore, the element with the fewest protons will generally have the largest atomic radius. Comparing \(\text{Li}\), \(\text{Be}\), \(\text{N}\), and \(\text{F}\), \(\text{Li}\) (Lithium) has the largest atomic radius.

Identify Highest Ionization Energy

Ionization energy increases across a period from left to right and decreases down a group. Between \(\text{Li}\), \(\text{Be}\), \(\text{N}\), and \(\text{F}\), \(\text{F}\) (Fluorine) has the highest ionization energy.

Identify Group 5A (15) Element

Group 5A (15) of the periodic table contains elements with five valence electrons. From the given elements, \(\text{N}\) (Nitrogen) fits this description.

Key concepts

alkaline earth metals

Alkaline earth metals belong to Group 2 of the periodic table. They include elements like Beryllium (Be), Magnesium (Mg), Calcium (Ca), and others. These elements are known for having two electrons in their outermost shell, which gives them specific chemical properties. For example, these metals are typically shiny, reactive (though not as reactive as alkali metals from Group 1), and have higher melting points than Group 1 elements.

• Alkaline earth metals easily form compounds with other elements.
• They are usually found in the Earth's crust only in compound form because of their reactivity.

In the provided list of elements, the only alkaline earth metal is Beryllium (Be).

atomic radius

The atomic radius refers to the distance from the center of an atom's nucleus to the outermost electron shell. This is important because it influences an element's reactivity and bonding characteristics. Atomic radius generally increases as you move down a group and decreases as you move from left to right across a period.

• Down a group: Electrons are added to new shells, making the atom larger.
• Across a period: Additional protons pull the electron cloud closer to the nucleus, reducing the atomic size.

For example, Lithium (Li) has the largest atomic radius among the given elements (Li, Be, N, F) because it is the element with the fewest protons and is located at the start of the period.

ionization energy

Ionization energy is the amount of energy required to remove an electron from a neutral atom in its gaseous phase. This property helps understand how strongly an atom holds onto its electrons. Ionization energy generally increases across a period from left to right and decreases down a group.

• Across a period: Atoms have more protons, increasing nuclear charge and holding electrons more tightly.
• Down a group: Electrons are farther from the nucleus and feel less pull, making them easier to remove.

Among the elements Li, Be, N, F, Fluorine (F) has the highest ionization energy because it is farthest to the right in its period and has a stronger nuclear pull on its valence electrons.

group 5A elements

Group 5A elements, also known as Group 15 elements, contain five valence electrons. This group includes elements like Nitrogen (N), Phosphorus (P), Arsenic (As), and others. These elements have varied chemical properties, but typically, they can form three bonds with other elements due to their five valence electrons.

• These elements can show multiple oxidation states.
• They are important in both organic and inorganic chemistry.

In the provided list, Nitrogen (N) is the element found in Group 5A, making it distinct from the others based on its electronic configuration and reactivity.