The Structure and Composition of the Earth

Reactivity Series: A specific list of metals categorized by the vigor with which they react; the list is arranged in order of decreasing chemical reactivity.
Melt: The physical process describing a change of state from a solid phase to a liquid phase.
Hypothermia: A clinical condition defined by a body temperature that is significantly lower than the normal physiological body temperature.
Extraction: The industrial or chemical process utilized to remove a metal from its source (typically ore within the Earth's crust).

The Core:
- Composition: Primarily composed of nickel and iron.
- Internal Divisions:
  - Outer Core: Characterized as being in a liquid (molten) state.
  - Inner Core: Characterized as a solid state.
- Geophysical Function: The presence of iron in the core is responsible for generating the Earth’s magnetic field. This magnetic field serves as a critical shield, protecting the planet from cosmic radiation emitted by the sun.
The Mantle:
- Thickness: Approximately $2,900\,km$ .
- Physical Properties: This layer possesses the qualities of a solid material, yet it retains a capacity for fluidity (‘flow’) under specific conditions. It is described as a semiaqueous or semi-solid substance.
The Crust:
- Thickness: Ranges from $10\,km$ to $100\,km$ .
- Classification: Noted for being very thin relative to the deeper layers of the planet.

Plates: The Earth's thin crust is not a continuous shell; rather, it is fragmented into several distinct pieces known as tectonic plates.
Mechanism of Movement:
- Tectonic plates are constantly in motion.
- This movement is driven by convection currents located within the semi-solid mantle.
- Because the mantle can flow despite having solid-like properties, the heat-driven currents within it carry the crustal plates along the surface.

Elements in the Crust:
- Oxygen: Constitutes $44.8\%$ of the crust.
- Silicon: Constitutes $21.5\%$ of the crust.
Elements in the Mantle:
- Magnesium: Comprises $22.8\%$ of the mantle.
Elements in the Core:
- According to estimates, the core consists of Iron and Nickel in roughly equal proportions.
- The core also contains various trace elements.

Seismic Wave Analysis: The internal structure and specific compositions of the Earth's layers are estimated by the scientific study of seismic waves.
Magnetic Field Analysis: Observations of the magnetic field provide data regarding the metallic composition and behavior of the core.

The Poster Assignment (Date: 19/05/2026):
- Objective: Create an informative poster detailing the properties and structure of the Earth.
- Format: Collaborative work in pairs, though students must maintain independent work standards.
- Standards: Students must ensure perfect spelling, punctuation, and grammar.
Poster Success Criteria:
- Inclusion of a visual model or picture of the Earth illustrating its various layers.
- Naming of all layers and a detailed description of their physical and chemical characteristics.
- Identification of specific elements found within the Earth's crust.
Peer Marking Plenary:
- Pairs are required to mark the work of other pairs based on the established success criteria.
- Feedback must include two positive aspects (‘good points’).
- Feedback must include one specific improvement target directly related to the success criteria.

Layer Identification: Name the layers in the Earth's structure (Crust, Mantle, Outer Core, Inner Core).
Crust Composition: Oxygen ( $44.8\%$ ) and Silicon ( $21.5\%$ ) are the primary elements identified.
Fragmentation of the Crust: The crust is split into tectonic plates.
Geodynamic Causes: Plates move because of convection currents originating in the mantle.
Magnetic Generator: The core (specifically through its iron content) is the layer that generates the protective magnetic field.