Different styles to say 'I Love You' - Spoken English Lesson

Liquid Basics

Liquids are the second state of matter we will talk about. Solids are objects you can hold and maintain their shape.

Gases are floating around you or trapped in bubbles. Liquids are found between the solid and gas states. Examples of liquids at room temperature include water (H2O), blood, and even honey. If you have different types of molecules dissolved in a liquid, it is called a solution. Honey is a solution of sugar, water, and other molecules. 

Liquids fill the shape of any container they are in. If you pour water in a cup, it will fill up the bottom of the cup first and then fill the rest. If you freeze that cup of water, the ice will be in the shape of the cup. 

The top of a liquid will usually have a flat surface. That flat surface is the result of gravity pulling on the liquid molecules. Let’s go back to the cup for a moment. If you put an ice cube (solid) into the cup, it will sit there and not change shape. As the cube warms and melts, the liquid water will fill the bottom of the cup and have a flat surface on top. 

Pushing on a Liquid

Another trait of liquids is that they are difficult to compress. When you compress something, you take a certain amount of material and force it into a smaller space or volume. You force the atoms closer together. Most solids are very difficult to compress while gases are easier. You can find compressed gases in SCUBA air tanks. Liquids are in the middle, but tend to be difficult to compress because the molecules are already close together. You probably can’t compress a liquid with your hands. It takes a lot of force. 

Many shock absorbers found in cars and trucks have compressed liquids, such as oils, in sealed tubes. Without shocks, there would be a very rough ride for the driver and a lot of stress on the structure of the car. The shocks counter the extremes of the up and down motion by acting as a dampening device. 

Molecules Sticking Together

Intermolecular forces are found in all substances. Some of the forces bring molecules together while others push them apart. Solids are locked together and you have to force them apart. Gases bounce everywhere and spread out. Many liquids want to stick together because of cohesive (sticky) forces that pull the molecules together. 

When you place a drop of water on a piece of glass, you will see it stay together as a drop. Cohesive forces keep the drop from spreading out. Cohesive forces also keep water molecules together if there is a drip on your faucet. The water sticks together until it is too heavy. It drips when the weight of the water drop overcomes the cohesive forces holding it all together. 

Evaporation occurs when individual liquid molecules gain enough energy to escape the system and become a gas. The extra energy allows individual molecules to overcome the intermolecular forces within the liquid. 

Solid Basics

What is one physical characteristic of a solid? Solids can be hard like a rock, soft like fur, a big rock like an asteroid, or small rocks like grains of sand. The key is that solids hold their shape and they don't flow like aliquid. A rock will always look like a rock unless something happens to it. The same goes for a diamond. Solids can hold their shape because their molecules are tightly packed together. 

You might ask, "Is baby power a solid? It's soft and powdery." Baby power is also a solid. It's just a ground down piece of talc. Even when you grind a solid into powder, you will see tiny pieces of that solid under a microscope. Liquids will flow and fill up any shape of container. Solids like to hold their shape. 

In the same way that a large solid holds its shape, the atoms inside of a solid are not allowed to move around too much.Atoms and molecules in liquids and gasesare bouncing and floating around, free to move where they want. The molecules in a solid are stuck in a specific structure or arrangement of atoms. The atoms still vibrate and the electrons fly around in their orbitals, but the entire atom will not change its position. 

Solid Mixtures

Solids can be made of many things. They can have pure elements or a variety of compounds inside. When you have a solid with more than one type of compound, it is called a mixture. Most rocks are mixtures of many different compounds. Concrete is a good example of a man-made solid mixture. 


Granite is a mixture you might find when you hike around a national park. Granite is made of little pieces of quartz, mica, and other particles. Because all of the little pieces are spread through the rock in an uneven way, scientists call it a heterogeneous mixture. Heterogeneous mixtures have different concentrations of compounds in different areas of the mixture. For example, there might be a lot of quartz and very little feldspar in one part of the granite, but only a few inches away those amounts might flip. 

Crystals

On the other end of the spectrum is something called a crystal. A crystal is a form of solid where the atoms are arranged is a very specific order. Crystals are often pure substances and not all substances can form crystals because it is a very delicate process. The atoms are arranged in a regular repeating pattern called a crystal lattice. Table salt (NaCl) is a great example of a crystal you can find around your house. The sodium (Na) and chlorine (Cl) atoms arrange themselves in a specific pattern to form the cubic salt crystals. 

Changing States of Matter

All matter can move from one state to another. It may require extreme temperatures or extreme pressures, but it can be done. Sometimes a substance doesn't want to change states. You have to use all of your tricks when that happens. To create a solid, you might have to decrease thetemperature by a huge amount and then add pressure. For example,oxygen (O2) will solidify at -361.8 degrees Fahrenheit (-218.8 degrees Celsius) at standard pressure. However, it will freeze at warmer temperatures when the pressure is increased. 

Some of you know about liquid nitrogen (N2). It is nitrogen from the atmosphere in a liquid form and it has to be super cold to stay a liquid. What if you wanted to turn it into a solid but couldn't make it cold enough to solidify? You could increase the pressure in a sealed chamber. Eventually you would reach a point where the liquid became a solid. If you have liquid water (H2O) at room temperature and you wanted water vapor (gas), you could use a combination of high temperatures or low pressures to solve your problem. 

Points of Change

Phase changes happen when you reach certain special points. Sometimes a liquid wants to become a solid. Scientists use something called a freezing point or melting point to measure the temperature at which a liquid turns into a solid. There are physical effects that can change the melting point.Pressure is one of those effects. When the pressure surrounding a substance increases, the freezing point and other special points also go up. It is easier to keep things solid when they are under greater pressure. 

Generally, solids are more dense than liquids because their molecules are closer together. The freezing process compacts the molecules into a smaller space. 

There are always exceptions in science. Water is special on many levels. It has more space between its molecules when it is frozen. The molecules organize in a specific arrangement that takes up more space than when they are all loosey-goosey in the liquid state. Because the same number of molecules take up more space, solid water is less dense than liquid water. There are many other types of molecular organizations in solid water than we can talk about here. 

CHEMISTRY TERM	PHASE CHANGE
Fusion/Melting Freezing Vaporization/Boiling Condensation Sublimation Deposition	Solid to Liquid Liquid to Solid Liquid to Gas Gas to Liquid Solid to Gas Gas to Solid