مراجعة هيكل امتحان في الكيمياء للصف العاشر متقدم - الفصل الثالث (2)

Chemistry الكيمياء

EoT3-Coverage Grade 10 Advanced

3مراجعة الهيكل الفصل متقدم10 الصف

• In a metallic lattice, the outer energy levels of the metal atoms overlap.
• The electron sea model proposes that all metal atoms in a metallic solid contribute their valence electrons to form a “sea” of electrons that surrounds the metal cations in the lattice.
• The electrons in the outer energy levels of bonding metallic atoms are called delocalized electrons. They can move from one atom to the next.
• When an atom’s outer electrons move freely throughout the solid, a metallic cation is formed.
• A metallic bond is the attraction of a metallic cation for delocalized electrons.
• The physical properties of metals at the bulk scale can be explained by metallic bonding.
• These properties provide evidence of the strength of metallic bonds.

Examples of physical properties of metals: — melting and boiling points — thermal and electrical conductivity — malleability, ductility, and durability — hardness and strength

In general, metals have moderately high melting points and high boiling points, as shown below.

• The melting points of metals are less extreme than the boiling points because the cations and electrons are mobile in a metal. It does not take much energy for them to move past each other.
• During boiling, atoms must completely separate from the lattice. This requires more energy.
• The movement of mobile electrons around positive metallic cations makes metals good conductors.
• Mobile electrons move heat from one place to another quickly.
• Mobile electrons easily move as part of an electric current when an electric potential is applied to a metal.
• Metals are malleable (can be hammered into sheets).
• Metals are ductile (can be drawn into wire).
• The figure below shows how an applied force causes metal ions to move through delocalized electrons, making metals malleable and ductile.