Valence electrons are those electrons in the outermost...

Valence electrons are those electrons in the outermost principal quantum level (highest n level) of an atom in its ground state. Groups 1A to 8A have from 1 to 8 valence electrons. For each group of the representative elements (1A–8A), give the number of valence electrons, the general valence electron configuration, a sample element in that group, and the specific valence electron configuration for that element.

Key Concepts

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom and play a key role in determining how the atom reacts chemically. They are crucial because they largely dictate an element's bonding behavior and its placement in the periodic table.

Electron Configuration

This concept involves the arrangement of electrons in various orbitals around an atom's nucleus. It explains which electrons occupy particular energy levels and subshells, helping us understand patterns in chemical reactivity and the periodicity of elements.

Periodic Table Grouping

The periodic table is organized into groups (columns) that contain elements with similar properties. In particular, the representative elements in groups 1A to 8A are grouped based on having a specific number of valence electrons, which leads to trends in their chemical behavior.

Representative Elements

Representative elements, found in groups 1A to 8A of the periodic table, are characterized by having their valence electrons arranged in a predictable manner. These elements exhibit trends in chemical reactivity and have general valence electron configurations linked to their group number.

Principal Quantum Number

The principal quantum number (n) indicates the main energy level of an electron in an atom. For valence electrons, it signifies the outermost energy shell, which is vital in defining the electron configuration and chemical properties of the element.

Transcript

00:01 The periodic table is arranged in a way to show the arrangement of all the electrons in any given atom.

00:08 Each row corresponds to a different energy level, and each column corresponds to a specific sub -level and the valence electrons that are found in each sub -level.

00:19 Valence electrons refer to the electrons in the outermost energy level.

00:24 And for the representative elements, or the elements found in the first two columns and the last six columns, the number of valence electrons is simply equal to the column in which they're found.

00:37 So every element in the first column has one valence electron.

00:44 Every element in the second column has two valence electrons.

00:50 Every element in this third column, skipping over our transition metals, has three valence electrons.

00:57 Similarly, you can see there are four, five, six, seven, and eight.

01:04 Valence electrons as you move across the row.

01:10 The number of valence electrons can be represented in a general electron configuration as well, which talks about the specific orbital in which the electron is found.

01:20 These first two columns correspond to the s orbitals.

01:25 And so every element in this block have an s one configuration.

01:33 So what that means is that their valence electrons will end an s one.

01:37 In this column, it's s2.

01:41 As we move over to look at the valence electrons in these six columns, this is the p block.

01:49 And so the first column should end in p1.

01:54 An element here would end in p2, p3, p4, p5, and finally p6.

02:08 So you can find the general electron configuration of a valence electron by looking at the column in which the element is found.

02:16 So for examples, for each column, you can see what the overall specific electron configuration is.

02:25 So let's start with sodium.

02:29 Sodium has 11 electrons, and because it's in the first column, i would expect that it ends in s1...

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