How do valence electrons determine chemical reactivity?

Answer 1

The valence electrons are the electrons in the outermost electron shell of an atom.

The bonding behavior of an atom is determined by the number of electrons in its outermost valence shell.

For this reason, elements in the Periodic Table that have an equal number of valence electrons in their atoms are grouped together.

Generally, elements in Groups 1, 2, and 13 to 17 tend to react to form a closed shell, corresponding to the electron configuration #s^2p^6#.

The bonded atoms have eight valence electrons, which is why this tendency is known as the "octet rule."

METALS

A metal from Group 1 is the most reactive type of metallic element (e.g., sodium or potassium).

Group 1 atoms only have one valence electron.

This one valence electron is easily lost to form a positive ion with an #s^2p^6# configuration (e.g., #"Na"^+# or #"K"^+#).
A metal from Group 2 (e.g., magnesium) is somewhat less reactive, because each atom must lose two valence electrons to form a positive ion (e.g., #"Mg"^(2+)#) with an #s^2p^6# configuration.

Reactivity rises with group membership in each group of metals.

Because the valence electrons are farther from the atom's nucleus, they are less firmly bound and simpler to extract.

METALS NOT IN USE

To reach a complete valence shell, a nonmetal has a tendency to draw in more valence electrons.

It can create an ionic bond by removing electrons from another atom or by sharing electrons with an adjacent atom to form a covalent bond.

Nonmetals that are halogens, like chlorine or fluorine, are the most reactive type.

It has an #s^2p^5# electron configuration, so it requires only one additional valence electron to form a closed shell.
To form an ionic bond, a halogen atom can remove an electron from another atom in order to form an anion (e.g., #"F"^-#, #"Cl"^-#, etc.).
To form a covalent bond, one electron from the halogen and one electron from another atom form a shared pair (e.g., in #"H–F"#, the dash represents a shared pair of valence electrons, one from #"H"# and one from #"F"#).

Because valence electrons in each group of nonmetals are at progressively higher energies and adding electrons does not significantly increase atom stability, reactivity decreases from top to bottom within each group.

Despite not being a halogen, oxygen, the lightest element in Group 16, is actually more reactive than chlorine due to its closer valence electrons to the nucleus.

Because they stand to gain a great deal from the reaction, a metal from Group 1's bottom, like potassium, and a nonmetal from Group 17's top, like fluorine, will react violently.

#"K"# loses one electron to #"F"# and forms the ionic compound potassium fluoride, #"K"^+"F"^-#.
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Answer 2

Valence electrons determine chemical reactivity because they are the electrons in the outermost energy level of an atom and are involved in forming chemical bonds with other atoms. The number of valence electrons determines an atom's ability to form bonds and participate in chemical reactions. Atoms tend to gain, lose, or share electrons to achieve a stable electron configuration, typically with a full outer shell. The reactivity of an atom is determined by its ability to gain, lose, or share electrons to achieve this stable configuration.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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