Wednesday, March 4 - Matter - Physical and Chemical Properties of Matter

Objective: Understand matter can be described by its physical properties and its chemical properties. Elements with similar properties are grouped together on the periodic table. Know that matter can change states.

Physical Properties

Physical properties are exactly what you’d think – the color, shape and size of matter. A physical property of matter is a characteristic that cab be observed without changing the matter into a different substance. Physical properties are properties that you can touch and feel – density, temperature, color. You want to measure physical properties that are unchanging. For example, looking at the color of water or measuring the density of water …. Those things don’t change. Measuring the mass or volume of water will change based on how much there is.

Try it: Fill a glass of water. Look at the physical properties of the water. Then dump half of it out. Observe which physical properties change and which ones stay the same.

Chemical Properties

Chemical properties are the ability or inability of a substance to react with or change into one or more new substances. Think of a silver spoon reacting with the air and tarnishing. Chemical properties can also be used to classify substances. Chemical properties occur when the composition of a substance changes and a new substance Is formed. Think of a car rusting. The rust is a new substance. It wasn’t there when you bought the car. It developed over time. It’s a new substance, not part of the metal of the car, but created when metals that contain iron combine with water and oxygen in the air. Another chemical property is flammability – the ability to burn.

States of Matter

Solid, liquid and has are all states of matter – they physical form matter can take. Water is the best example of this – ice, water, and steam (vapor). When matter changes from one state to another, thermal energy is absorbed or released. When matter is heated, it absorbs thermal energy. When it cools, it releases thermal energy. All matter needs to be heated or cooled to change state.

The melting point is when matter goes from solid to liquid. The melting point can help identify a substance. For example, the melting point of water is 0 degrees Celsius. The melting point of table salt is 801 degrees Celsius. When a substance melts, the particles vibrate so intensely, they move past each other.

The freezing point is when matter goes from liquid to solid. Here, a substance cools and the particles slow down and come closer together until they become a solic.

Vaporization is the point when a liquid absorbs enough energy to become a gas. Vaporization occurs in two ways – boiling and evaporation. Boiling is when vaporization happens throughout the liquid. Evaporation is when vaporization happens on the surface of the liquid. Essentially, the liquid absorbs so much energy, the particles spread apart and become a gas.

Condensation is when vapor or gas cools and the particles slow down, come together and become a liquid.

Under certain conditions, matter can go from being a solid to a gas without passing through the liquid phase. This is Sublimation. This is when the particles of a solid absorb so much energy, they become a gas. This is what happens with dry ice.

Because elements with similar properties are grouped together on the periodic table of elements, you can predict a lot about an element's properties based on where it is on the periodic table.