What is the fundamental difference between the oxides of metals and non-metals?

Metal oxides are generally basic or amphoteric, meaning they react with acids to form salt and water. Non-metal oxides are typically acidic or neutral, reacting with bases to form salts.

How do malleability and ductility differ in terms of physical application?

Malleability is the property that allows a material to be beaten into thin sheets without cracking. Ductility is the ability of a material to be stretched into thin wires.

Why can a more reactive metal displace a less reactive metal from its salt solution?

A more reactive metal has a stronger tendency to lose electrons and form ions. It 'forces' the less reactive metal ions in the solution to accept electrons and return to their elemental, solid state.

Why is it a mistake to assume all metals are solid at room temperature?

Mercury is a notable exception as it exists in a liquid state at room temperature. This is due to its unique electronic structure which weakens the metallic bonding between its atoms.

What error is made when trying to displace hydrogen from dilute acids using Copper?

Copper is lower than hydrogen in the reactivity series. Therefore, it is not reactive enough to donate electrons to hydrogen ions, resulting in no reaction with dilute acids.

Why is Graphite an exception to the rule that non-metals are poor conductors?

In graphite, each carbon atom is bonded to only three others, leaving one free valence electron per atom. these delocalized electrons are free to move, allowing electricity to flow.

Define 'Amphoteric Oxides' and provide an example.

Amphoteric oxides are metal oxides that show both acidic and basic behavior, reacting with both acids and bases to produce salt and water. Examples include Aluminum oxide ($Al_2O_3$) and Zinc oxide ($ZnO$).

What is 'Aqua Regia' and why is it significant?

Aqua Regia is a freshly prepared mixture of concentrated Hydrochloric acid and concentrated Nitric acid in a 3:1 ratio. It is significant because it can dissolve noble metals like Gold and Platinum which do not react with single acids.

What is the 'Reactivity Series'?

It is a list of metals arranged in the order of their decreasing chemical activity. It helps predict the outcome of displacement reactions and determines the appropriate method for metal extraction.

Why do ionic compounds have high melting points?

Ionic compounds consist of a giant lattice of oppositely charged ions held together by very strong electrostatic forces. A large amount of thermal energy is required to overcome these strong attractions and break the lattice.

Metals & Non-Metals | OCR GCSE Chemistry

2. Elements, compounds & mixtures

Metals & Non-Metals

Summary

The classification of elements into metals and non-metals is based on their physical and chemical properties, primarily driven by their electronic configurations. Metals tend to lose electrons to form positive ions (cations), while non-metals tend to gain or share electrons to form negative ions (anions) or covalent bonds, leading to distinct behaviors in conductivity, reactivity, and bonding.

1. Definition & Core Concepts

Metals are electropositive elements that typically possess 1, 2, or 3 electrons in their valence shell, which they readily lose to achieve a stable octet. This electron loss results in the formation of positive ions, making metals essential components in ionic compounds.
Non-metals are electronegative elements that usually have 4 to 8 valence electrons. They achieve stability by gaining electrons to form negative ions or by sharing electrons with other non-metals through covalent bonding.
Metalloids represent a small group of elements that exhibit properties intermediate between metals and non-metals. They are often semi-conductors, meaning their electrical conductivity can be manipulated, which is vital for modern electronics.

2. Physical Properties & Structural Basis

Conductivity: Metals are excellent conductors of heat and electricity due to the presence of 'free' or delocalized electrons that can move through the crystal lattice. In contrast, non-metals (except graphite) lack these mobile charge carriers and act as insulators.
Mechanical Properties: Metals exhibit malleability (can be hammered into sheets) and ductility (can be drawn into wires) because their atomic layers can slide over each other without breaking the metallic bond. Non-metals in solid state are typically brittle and shatter upon impact.
Luster and Sonority: Metals possess a characteristic shine known as metallic luster and produce a ringing sound when struck (sonority). These properties are absent in non-metals, which generally appear dull and do not resonate when hit.

Diagram comparing the 'sea of electrons' in metallic bonding versus the shared electron pairs in non-metal covalent bonding.

3. Chemical Properties & Reactivity

4. The Reactivity Series

5. Ionic Bonding: Metal to Non-Metal

Formation: Ionic bonds are formed through the complete transfer of electrons from a metal atom to a non-metal atom. This creates an electrostatic attraction between the resulting oppositely charged ions.
Properties of Ionic Compounds: These substances typically form crystalline solids with high melting and boiling points due to the strong inter-ionic forces. They are generally soluble in water but insoluble in organic solvents.
Electrical State: In solid form, ionic compounds do not conduct electricity because ions are fixed in a lattice. However, they become excellent conductors when molten or dissolved in water, as the ions are free to move.

6. Exam Strategy & Tips