Question

How many valence electrons does each of the following dietary trace elements have? (a) Zinc (b) Iodine (c) Silicon (d) Iron

Short answer

(a) Zinc: 2, (b) Iodine: 7, (c) Silicon: 4, (d) Iron: 2 or 3

Step-by-step solution

Understanding Valence Electrons

Valence electrons are the outermost electrons of an atom that can participate in forming chemical bonds with other atoms. The number of valence electrons typically determines an atom's chemical properties.

Determining Zinc's Valence Electrons

Zinc is located in group 12 of the periodic table. Group 12 elements usually have 2 valence electrons. Therefore, zinc has 2 valence electrons.

Determining Iodine's Valence Electrons

Iodine is located in group 17 (halogens) of the periodic table. Group 17 elements have 7 valence electrons. Therefore, iodine has 7 valence electrons.

Determining Silicon's Valence Electrons

Silicon is located in group 14 of the periodic table. Group 14 elements have 4 valence electrons. Therefore, silicon has 4 valence electrons.

Determining Iron's Valence Electrons

Iron is located in group 8 of the periodic table, which is a transition metal group. For transition metals like iron, the concept of valence electrons can be more complex due to their d-electrons, but narrowing it down for simplicity, iron typically has 2 or 3 valence electrons.

Key concepts

Periodic Table Groups

The periodic table is organized into vertical columns known as groups. Each group contains elements with similar chemical properties due to having the same number of valence electrons in their outermost shell. This makes it easier to predict how elements will react with one another.

• Group 1, the alkali metals, all have 1 valence electron, making them highly reactive.
• Group 2, the alkaline earth metals, have 2 valence electrons.
• Groups 13 to 18 contain elements with 3 to 8 valence electrons respectively, including non-metals like carbon and oxygen.
• Group 17 is particularly notable for the halogens, like iodine, which have 7 valence electrons. They tend to form bonds easily due to their high reactivity.

Understanding the group an element belongs to provides insight into its electron configuration and overall behavior in chemical reactions.

Chemical Bonding

Chemical bonding involves the interaction of two or more atoms to form a greater structure such as a molecule or compound. These bonds are formed primarily through the electrons in the outermost shell of an atom—known as the valence electrons.

• Covalent bonds occur when atoms share electrons, typical in non-metal elements like silicon.
• Ionic bonds form when electrons are transferred from one atom to another, often between metals and non-metals, creating ions with full outer shells.
• Metallic bonds are found in metals, where electrons form a "sea" that is shared among many atoms, explaining properties like conductivity and malleability.

The electron arrangement in the valence shell heavily influences the type and strength of bonds an element can form.

Transition Metals

Transition metals are a fascinating category of elements found in the central block of the periodic table. These metals are known for their distinctive ability to form a variety of oxidation states, due to the electrons in their d sub-shells. This can complicate the determination of valence electrons.

• Elements like iron, which is a transition metal, often have valence electrons numbering between 2 and 3. This variability allows them to form complex ions and act as catalysts in chemical reactions.
• Transition metals are often lustrous, with high melting points and densities, which contributes to their wide range in industrial applications.
• These metals also have the unique characteristic of forming colored compounds, due to electronic transitions among their d electrons.

Understanding transition metals requires acknowledging their flexible electron configurations, making them critical for many chemical processes and practical applications.