10.7Chapter 10: Structure, Bonding, and Properties

More about structures — Alhussan Chemistry - Stage 9 Revision Notes & Topical Questions

5 min read 9 parts Lesson 7 of 9 2 quizzes

📚 Alhussan Chemistry - Stage 9 Hub / Topical Revision

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Lesson summary

10.7 More about structures — Bonding, Melting Points and Conductivity — Alhussan International Academy — Chemistry (Stages 7–9) notes: Describe giant metallic structures, summarise the four types of structure and use data to identify bonding and structure.Alloys — steel is mainly…

Metallic bonding
High strength and melting points
Steel in buildings
Explanation pattern
Comparisons
Non-metals

Part 1 of 7Giant metallic structures

Giant metallic structures

Alloys

Alloys steel is mainly iron with small amounts of other elements, and metal elements and alloys are strong because of their structure.

Particles

Particles metal atoms lose their outer electrons to achieve a stable electron configuration,
so a metal contains two types of particle: positive ions and negative electrons.
The ions are in fixed positions in layers.
The electrons move around between the ions.

Metallic bonding

Metallic bonding the electrostatic attraction between positive metal ions and moving negative electrons, which holds the metal together.

Giant metallic structure

Giant metallic structure the three-dimensional pattern of positive metal ions held together by moving electrons.

Part 2 of 7Properties of metals

Properties of metals

High strength and melting points

High strength and melting points the strong electrostatic attraction between fixed positive ions and moving electrons needs a lot of energy to overcome.

Conductivity

Conductivity the moving electrons allow metals to conduct electricity, even as solids.

Steel in buildings

Steel in buildings steel bars embedded in concrete give the strength needed in a tall building such as the Burj Khalifa in Dubai.

Part 3 of 7Four types of structure

Structure	Particles	Elements or compounds	Typical state at 20 °C	Examples
Ionic (giant)	Positive and negative ions	Compounds	Solid	Sodium chloride
Metallic (giant)	Positive ions and negative electrons	Elements	Solid	Gold
Giant covalent	Atoms joined by covalent bonds	Elements and compounds	Solid	Diamond, silicon dioxide
Simple covalent	Molecules joined by covalent bonds	Elements and compounds	Liquid or gas	Hydrogen, carbon dioxide

Part 4 of 7Evidence for each structure

Property	Ionic lattice	Simple molecular	Giant covalent	Metallic
Melting point	High	Low	Very high	Usually high
Conducts as solid	No	No	No (graphite yes)	Yes
Conducts when molten	Yes	No	No	Yes
Soluble in water	Often	Rarely	No	No

Part 5 of 7Why bonding determines the property

Melting point

Melting point it depends on how much energy is needed to overcome the attractions between particles.
In ionic compounds there are strong electrostatic forces in all directions.
In simple molecular substances only the weak forces between molecules are overcome.
In giant covalent structures many strong covalent bonds must be broken.

Conductivity

Conductivity it needs charged particles that can move.
Ions carry charge when molten or dissolved.
Delocalised electrons carry charge in metals and graphite.

Part 6 of 7Identifying an unknown substance

Check the melting point: a low value suggests simple molecules.

If the melting point is high, check whether the solid conducts: if it does, it is a metal (or graphite).

If it does not conduct as a solid but conducts when molten or in solution, it is ionic.

If it never conducts and has a very high melting point, it is giant covalent.

Explanation pattern

Explanation pattern state the structure, describe the particles and forces, and link them to the property.

Comparisons

Comparisons magnesium oxide melts higher than sodium chloride because of higher charges and stronger attraction.
Diamond is harder than graphite because of a rigid network versus sliding layers.

Part 7 of 7Structure and the periodic table

Structure and the periodic table

Metals

Metals all metal elements have giant metallic structures.

Non-metals

Non-metals most exist as molecules, and a few have giant covalent structures.

Noble gases

Noble gases they exist as single atoms.

No ionic elements

No ionic elements no element has a giant ionic structure, because ionic structures need two different types of ion, so they occur only in compounds.

Prediction

Prediction knowing the structure of an element helps predict its properties.

Key terms

Term	Meaning
Melting point	the temperature at which a solid turns to liquid.
Electrical conductor	a material that allows charge to flow.
Intermolecular force	a weak attraction between molecules.
Metallic bonding	attraction between positive ions and moving electrons.
Alloy	a mixture of a metal with other elements.
Giant metallic structure	a pattern of positive metal ions held by moving electrons.