Question

Write an electron configuration for \(\mathrm{N}\) . Then write a Lewis symbol fo \(\mathrm{Ne}\) and show which electrons from the electron configuration are included in the Lewis symbol.

Short answer

The electron configuration for Nitrogen (N) is 1s2 2s2 2p3. The Lewis symbol for Neon (Ne) shows 8 valence electrons (2s2 2p6) as dots around the Ne symbol.

Step-by-step solution

Determine Electron Configuration for Nitrogen

Nitrogen has an atomic number of 7, which means it has 7 electrons. The electron configuration can be determined by adding electrons to the orbitals in the order of increasing energy levels. The order of filling starts with the 1s orbital, followed by the 2s and then the 2p orbitals. The electron configuration of Nitrogen will therefore be: 1s2 2s2 2p3.

Write the Lewis Symbol for Neon

Neon has an atomic number of 10, which means it has 10 electrons. A Lewis symbol represents the valence electrons as dots around the element's symbol. Neon's electron configuration is 1s2 2s2 2p6, with 8 valence electrons (the electrons in the highest energy level). In the Lewis symbol, the 2s2 and 2p6 electrons are shown as dots around the symbol for Neon (Ne), with one dot for each valence electron.

Identify Valence Electrons in the Lewis Symbol

All electrons in the outermost shell (the valence shell) are represented in the Lewis symbol. For Neon, this includes all the electrons in the second principal energy level (2s and 2p orbitals).

Key concepts

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom that can participate in chemical bonding. They are extremely important because they determine the chemical properties and reactivity of an element. By the rules of electron configuration, these are typically the electrons in the highest energy level of an atom.

For example, nitrogen (N) has an atomic number of 7 suggesting it has 7 electrons when neutral. This means its electron configuration, following the order of increasing energy levels, is 1s2 2s2 2p3. While the 1s and 2s electrons are closer to the nucleus and more tightly bound, it is the three 2p electrons that are counted as valence electrons as they occupy the highest energy level in nitrogen's configuration.

These valence electrons are the ones that will interact with other atoms to form chemical bonds, such as covalent bonds where electrons are shared between atoms. When teaching students about valence electrons, it's crucial to emphasize their role in chemical reactions and how they influence molecules' structures and properties.

Lewis Symbol

A Lewis symbol, also known as a Lewis dot diagram, is a graphical representation that illustrates the valence electrons for an atom or a monatomic ion. The symbol consists of the elemental symbol surrounded by dots that represent the valence electrons. These dots are placed around the elements' symbols in pairs to represent the pairing of electrons that occurs in orbitals.

For example, the Lewis symbol for neon (Ne) is represented with 8 dots surrounding the symbol 'Ne' because neon has 8 valence electrons. In the case of neon, its electronic configuration is 1s2 2s2 2p6. The full outer shell (8 electrons) is what makes neon a noble gas, chemically stable and unlikely to form bonds under normal conditions.

When illustrating Lewis symbols, it’s valuable to highlight that the representation is a simplified model focusing on valence electrons and doesn’t necessarily reflect how electrons are spatially distributed around the nucleus.

Atomic Number

The atomic number of an element, often denoted as Z, is a fundamental property that defines the identity of the element. It indicates the number of protons in the nucleus of an atom, which also equals the number of electrons in a neutral atom. The atomic number determines an element's position in the periodic table and its chemical behavior.

As we've seen with nitrogen and neon, their atomic numbers are 7 and 10 respectively. This number not only tells us the count of protons and electrons but also guides us in determining the electron configuration. Students should understand that the atomic number is distinct for each element and serves as a unique identifier, much like a fingerprint for atoms. It’s also pertinent to mention to students that the atomic number plays a key role in defining the types of chemical bonds an atom can form based on its valence electrons.