(c) An atom has the electron configuration 1s 2 2s 2 2p 6 3s 2 3p 2 . How many valence electrons does the atom have?

everyone in this example. We need to determine valence electrons for an atom with the given electron configuration. So based on this configuration, we have 1 S2, two S 22 P 63 S two and three P two. So it's clear that we fully fill in our orbital's up to the third energy level. Where in the peace sub level we only fill in two electrons. We should recall that R p sublevel has a total of three orbital's which can hold a maximum of six electrons. However, in our configuration here, we've only applied to electrons or filled in two electrons. So we're gonna go to the third period of our periodic table to get to the third energy level. And we're gonna go to the P block beginning at group three A and when we count for two units which would represent our two electrons that we fill in. We would see that this is a configuration for Adam silicon. Now we want to recall that for valence electrons, those are going to be the electrons in our outermost energy level. Or we can say sublevel. And so our outermost sub level is going to be the sub level with the highest energy level. And that's going to be the third energy level as we see here. So this is our valence orbital's where we would add the exponents which represent our electrons to get our number of valence electrons. So we would have two plus two which would give us four valence electrons. And for our final answer this is our value for valence electrons for atoms of silicon. So I hope that everything I went through is clear. If you have any questions, please leave them down below what's boxed in and blue represents our final answer, and I will see everyone in the next practice video.

Ch.8 - Basic Concepts of Chemical Bonding

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Brown 15th Edition

Ch.8 - Basic Concepts of Chemical Bonding

Problem 11c

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Chapter 8, Problem 11c

(c) An atom has the electron configuration 1s²2s²2p⁶3s²3p². How many valence electrons does the atom have?

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Identify the highest principal quantum number (n) in the given electron configuration. This number indicates the outermost shell of the atom.

Locate the subshells (s, p, d, f) associated with the highest principal quantum number. In this case, look at the electrons in the 3s and 3p subshells.

Count the total number of electrons in these subshells. The number of electrons in these subshells represents the number of valence electrons.

Sum the electrons in the 3s and 3p subshells to find the total number of valence electrons.

The total number of electrons in the 3s and 3p subshells is the number of valence electrons the atom has.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. It is represented by a series of numbers and letters indicating the energy levels and types of orbitals occupied by electrons. Understanding electron configuration is essential for determining the chemical properties of an element, including its reactivity and bonding behavior.

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom that are involved in chemical bonding. They determine how an atom interacts with other atoms and are crucial for understanding an element's reactivity. The number of valence electrons can be deduced from the electron configuration, particularly from the highest principal energy level.

Principal Energy Levels

Principal energy levels are the layers of electrons surrounding the nucleus of an atom, denoted by the principal quantum number (n). Each level can hold a specific number of electrons, and the outermost level contains the valence electrons. Identifying the principal energy levels helps in understanding the structure of the atom and predicting its chemical behavior.