3.1 Water

• Natuurkunde / Scheikunde
• Middelbare school
• havo, vwo
• Leerjaar 2

Chapter 3.1 Water

Schedule for this lesson

Explanation about the new paragraph

Looking at a simulation

Making question in the workbook

Learning objectives

You can recognize the three phases of water in practice

You can describe the three phases in which water can occur using the particle model

You can use the particle model to explain why ice and many other solid substances have characteristic crystal structures

Three phases

What do we see in these pictures?

• Rain, mist, snow, hail and dew all look very different 

• But they all consist of one substance, water!

Three phases

Water, like many other substances can exist 

in three different states, also known as phases

• As a solid substance - ice

•  As a liquid - water

• As a gas - water vapour

Three phases

Other examples of solid substances are wood and bricks 

Three phases

Other examples of liquids are gasoline and alcohol

Three phases

Other examples of gasses are oxygen (O2) and carbon dioxide (CO2)

These gasses are in the air, we can't see them

Phases in the particle model

You can't see how the molecules of a substance move

But you can try to picture it in your head

You can imagine how to molecules move around and how they affect one another

Phases in the particle model

In physics and chemisty the particle model is widely used

In this model a substance is always made up of the same molecules, no mather the phase

A substance can exist in different phases because the molecules can move in various ways

Phases in the particle model

To demonstrate this we will take a look at this website

We will look at the position of the molecules, and at the volume

https://phet.colorado.edu/sims/html/states-of-matter-basics/latest/states-of-matter-basics_all.html

Phases in the particle model

Now we know that in solid substances, all molecules have fixed positions, they can still move, but only by vibrating back and forth.

This is why ice cubes also have a fixed shape

Phases in the particle model

In liquids molecules don't have a fixed position. they can move around past other molecules. Water drops don't have a fixed shape because of this. The molecules do remain together as close as possible. 

Phases in the particle model

Molecules in gasses are able to move freely. They spread out to fill the space the gas is in. The distance between molecules is large. 

Crystals

Snow is made up of ice crystals which can have 

different shapes

But all those shapes exist of the same six-sided

structures

This is called a crystal structure

Crystals

The particle model lets you explain why crystals have fixed shapes.

Because all molecules in a substance are identical, they can 'stack' in regular patterns , this creates a crystal lattice (kristalstructuur) in which every molecule has a fixed position 

Making question

Make the following questions: 1, 2, 3, 4, 5, 6 and 9

What did we learn today?

In today's lesson we talked about the three different phases

Which phases?

• Solid
• Liquid
• Gas

• Could 

End of the lesson