DESCRIBING MATTER & STATES OF MATTER

DESCRIBING MATTER

KWL Chart on Matter

https://vimeo.com/61925438

WHAT IS MATTER MADE OF?

Scientists know that all matter in the universe is made of more than 100 different substances, called elements.

An element is a substance that cannot be broken down into any other substances by physical means. Elements are the simplest substances. Each element has specific physical and chemical properties, which can be used to identify it. Elements are represented by one- or two-letter chemical symbols.

According to the particle theory, all matter is made up of atoms. An atom is the basic particle from which all elements are made.

An atom has a positively charged center, or nucleus, surrounded by a negatively charged “cloud.”

• Atoms of most elements can combine with other atoms by forming chemical bonds.

• A chemical bond is a force of attraction between two atoms. The result of a chemical bond is often a molecule, or a group of two or more atoms held together by chemical bonds.

• A molecule can be made of atoms of different elements of atoms of the same element.

• A compound is another type of substance. A compound is made of two or more elements that chemically combined in a set ratio. A compound is represented by a chemical formula, which shows the elements in the compound and the combining ratios of their atoms.

• When elements combine chemically, they form compounds different from those of the elements. Ex. NaCl

• Elements and compounds are substances, but most materials are mixtures.

• A mixture is made of two or more substances that are together in the same place but whose atoms are not chemically combined. Each substance in a mixture keeps its own properties and is not combined in a fixed ratio.

• A mixture can be heterogeneous or homogeneous. In a heterogeneous mixture, the different parts cab usually be seen and easily separated.

• The substances in a homogeneous mixture are so evenly mixed that they cannot be seen and are difficult to separate.

• Methods used to separate mixtures include filtration, distillation, evaporation and magnetic attraction.

STATES OF MATTER!

http://www.brainpop.com/science/matterandchemistry/statesofmatter/ • How do you describe a solid?

The particles in a solid are packed tightly together, vibrating slightly about their positions. This fixed, closely packed arrangement of particles in a solid causes it to have a definite shape and volume.

There are two types of solids: Crystalline solids and amorphous solids.

• How do you describe a liquid?• The particles in a liquid are packed almost as closely as those in a solid, but

they can move around each other freely. Because its particles are free to move, a liquid has no definite shape. However, it does have definite volume.

• Liquids are also called fluids, meaning “substances that flow.” Viscosity is a fluid’s resistance to flow. For example, honey has a higher viscosity than water.

• Liquids have surface tension, an force that brings molecules of the surface closer together.

• How do you describe a gas?Like a liquid, a gas is also a fluid. Gas particles move in all directions.

As they move, gas particles spread apart, filling all the space available. Thus a gas has neither definite shape nor definite volume.

The volume of a gas is the same as the volume of the container; the particles just move farther apart or closer together.

The temperature of a gas or any other substance is a measure of the average energy of motion of the particles. The faster the particles are moving, the greater their energy and higher the temperature.

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