Question

Why should magnesium form a metallic solid?

Short answer

Magnesium forms a metallic solid due to its atomic structure which allows it to easily donate electrons and form positive ions. These ions form a regular lattice with delocalized electrons moving freely throughout, allowing for conduction of electricity and heat, contributing to its properties as a metallic solid.

Step-by-step solution

Understand Metallic Bonding

A metallic bond is a type of chemical bond formed between positively charged ions with delocalized electrons around them. These delocalized electrons free to move and hence conduct electricity, contributing to the characteristic properties of metals such as malleability and ductility. It is the principal bond type in solid magnesium.

Discuss the Structure of Magnesium Atom

Magnesium atom, with the atomic number 12, has two electrons in its outer shell which can easily be donated to form a positively charged ion. These free electrons can delocalize over the whole of the metal lattice, forming a 'sea of delocalized electrons'.

Explanation of Magnesium’s Behaviour

The positively charged magnesium ions form a regular pattern or lattice, and the delocalized electrons, which are not associated with any one particular ion, can move freely throughout the lattice. This free movement of electrons within a lattice of positive ions contributes to the high electrical and thermal conductivity of metals and their malleability. Thus, because of these properties, magnesium forms a metallic solid.

Key concepts

Chemical Bonds in Metals

Understanding the foundations of metallic bonding is essential in comprehending why elements like magnesium form a metallic solid. Imagine a dance floor filled with dancers; similarly, in metallic bonds, metal atoms release some of their electrons, becoming positively charged ions. These ions are the 'dancers,' arranged in a precise pattern in what is known as a metallic lattice.

Now, the electrons that were released become part of a 'sea of electrons' that flows freely around the lattice of ions. This ability of electrons to move throughout provides metals with distinctive characteristics. For instance, these free-flowing electrons allow metals to conduct electricity, since they can carry electrical current from one place to another. Additionally, because the electrons are not fixed in place and can move to accommodate shifts in the lattice, metals are malleable and can be shaped or bent without breaking. Thus, the chemical bonds in metals are not just attractions between fixed partners, but are more like a communal sharing of electrons that endow metals with their unique properties.

Properties of Metals

Metals are synonymous with strength and flexibility. A few key properties define their behavior in the physical world. Metals tend to be lustrous, reflecting light in a shiny way due to the free movement of electrons on their surface. They are typically hard, yet ductile, meaning they can be drawn out into wires.

Thermal and Electrical Conductivity

Metals are excellent conductors of heat and electricity, a characteristic arising from their sea of delocalized electrons that can transfer energy efficiently.

Malleability and Ductility

When force is applied to a metal, its ions can roll over each other into new positions without breaking the metallic bond. This makes them malleable, and able to be hammered or pressed into different shapes without shattering. Their ductility is a related quality, allowing them to sustain stress and pull into thin wires.

Reactivity with Other Elements

Metals can readily lose electrons to form positive ions, a trait that affects their chemical reactivity. Some metals, like sodium, react rapidly with air or water, whereas others, like gold, are remarkably unreactive.

Magnesium Atomic Structure

Magnesium is the ninth most abundant element in the universe and plays a pivotal role due to its unique atomic structure. The atom of magnesium possesses an atomic number of 12, meaning it has 12 protons in its nucleus and, when neutral, 12 electrons orbiting around it. These electrons are arranged in 'shells' or energy levels - 2 fill the first shell, 8 in the second, and the remaining 2 in the third shell.

These two outermost electrons can be easily donated to the metallic bond’s sea of electrons, thus forming a Mg²⁺ ion. The loss of these relatively loosely held outer electrons is what allows magnesium to participate in the formation of a metallic lattice structure. The magnesium ions then take their place in the crystal lattice, surrounded by a sea of mobile electrons that glue the ions together with a metallic bond. This structure is not only responsible for magnesium's metallic properties but also influences its reactivity and interaction with other elements. The ease with which magnesium atoms can donate their outer electrons also facilitates its involvement in many chemical reactions, including its crucial roles in biological systems.