Beginning in Year 4 (aged 8+), students will explore different states of matter and how it changes, with deposition as one component.
Deposition refers to the process of depositing material on surfaces through various means, the most well-known being atomic layer deposition used extensively in semiconductor manufacturing and other fields of science.
Erosion is the process of moving weathered rock materials across landscapes to new places, often via human intervention. Erosion occurs naturally but can also be hastened by human actions like plowing the soil. When farmers plow, leaving exposed to strong winds and heavy rainfall, which over time leads to its erosion. Erosion also happens when ranchers allow livestock overgraze an area, leaving behind few groundcover plants to hold onto soil structure and thus accelerates erosion.
Water is one of the primary agents of erosion. It washes away soil and carves out canyons like Namibia’s Fish River Canyon due to the river’s relentless current. Erosion also occurs through glaciers collecting rock materials before discharging their load back onto other places as they melt; this type of physical erosion is known as mechanical erosion.
Condensation is the process by which substances change from gaseous to liquid states, serving an important function in Earth’s water cycle. At temperatures below their dew point, substances lose their ability to stay gaseous; instead their molecules start moving more slowly around surfaces before losing thermal energy and condensing into droplets of liquid that then fall to Earth as rain or dew; condensation also creates fog and clouds.
As part of everyday experiences, condensation may be familiar. You might have witnessed water droplets forming on cold windows or mirrors after an especially warm, sunny day, for instance. Condensation plays an integral role in nature’s water cycle and accounts for many weather phenomena like fogging, rain or snowstorms that we see every day.
Sublimation is the process by which solids directly transform into gaseous states without first going through liquid phases. This transition is measured using its enthalpy, or how much energy it requires to switch a mole of substance from solid, to liquid, then gas. Sublimation only works at extremely low temperatures – examples being water vapour generated when exposed to freezing cold air or dry ice turning into carbon dioxide gas.
Students explore states of matter and changes between them from year 4 (aged 8+). Sublimation is an invaluable concept that can be seen daily such as frost, snow and cirrus clouds.
Sublimation can be demonstrated by heating purple iodine vapor and then covering it with ice to form needle-shaped crystals of solid iodine without creating liquid form. A similar effect can be observed by hanging wet clothing outside on below-freezing days until all ice gradually melts away.
Deposition occurs when natural forces such as water, wind, gravity and glaciers move sand, silt and gravel from one location to the next using various means such as gravity. This process creates many landforms including dunes, gravel bars and beaches as well as sedimentary rock layers such as limestone chalk and coal deposits.
Speed and terrain of an agent participating in deposition are important considerations. Particle size and density have an effect on how far particles travel; heavier ones tend to settle closer while light ones travel further away from their point of origin. Shape also plays an important role; round particles settle more rapidly than flat ones.
Students aged 8+ should begin exploring states of matter and the transformation between gases and liquids in Year 4. Students may begin considering condensation as a form of deposition – for instance when frost forms on window panes – although this should not be confused with sublimation, which involves changing directly from gaseous state to solid state without passing through liquid phase; an example could be water vapour turning to ice on cold surfaces.