- Determine the valence electrons for each element based on their atomic number: Carbon has 4, Neon has 8, Silicon has 4, and Barium has 2.
- Compare these counts to find elements with the same number.
- Carbon and Silicon both possess 4 valence electrons.
- The two elements with the same number of valence electrons are \(\boxed{\text{carbon and silicon}}\).
Explanation
- Analyzing the Problem Data
The problem asks us to identify which two elements from the list {barium, neon, silicon, carbon} have the same number of valence electrons. Valence electrons are the electrons located in the outermost shell of an atom, and they determine how an atom interacts with others. For neutral atoms, the number of valence electrons generally corresponds to the element's group in the periodic table. We are given the following atomic numbers: barium (56), neon (10), silicon (14), and carbon (6).
- Determining Valence Electrons for Each Element
To find the valence electrons, we determine the electron configuration or group for each element based on its atomic number (Z):
- Carbon (C, Z=6): The electron configuration is \(1s^2 2s^2 2p^2\). The outermost shell is the \(n=2\) shell, containing \(2+2=4\) valence electrons. Carbon belongs to Group 14.
- Neon (Ne, Z=10): The electron configuration is \(1s^2 2s^2 2p^6\). The outermost shell is the \(n=2\) shell, containing \(2+6=8\) valence electrons. Neon belongs to Group 18 (noble gas).
- Silicon (Si, Z=14): The electron configuration is \(1s^2 2s^2 2p^6 3s^2 3p^2\). The outermost shell is the \(n=3\) shell, containing \(2+2=4\) valence electrons. Silicon belongs to Group 14.
- Barium (Ba, Z=56): Barium is an alkaline earth metal in Group 2. It has an electron configuration ending in \(6s^2\), which means it has 2 valence electrons in its outermost shell.
- Conclusion and Final Answer
Comparing the number of valence electrons for each element:
- Carbon: 4 valence electrons
- Neon: 8 valence electrons
- Silicon: 4 valence electrons
- Barium: 2 valence electrons
By comparing these results, we can see that carbon and silicon both have 4 valence electrons. Therefore, these are the two elements from the list that share the same number of valence electrons.
Examples
Understanding valence electrons is essential for predicting chemical behavior. Just as silicon and carbon share properties because they have the same number of valence electrons, knowing an element's valence shell helps chemists design new materials, such as semiconductors (which often utilize group 14 elements like carbon and silicon) or stable chemical compounds. This principle allows scientists to group elements with similar reactive properties together in the periodic table.