Matter and the Changes it undergoes It MATTERS very much! Matter and the Changes it undergoes

What is Chemistry? Chemistry is the study of matter and the transformations it can undergo. Matter is any substance that has mass and volume. An atom is the smallest unit of matter that maintains its chemical identity.

Kinetic Molecular Theory Describes the forces between molecules and the energy they possess. Matter is made of atoms/molecules. Volume comes from the space between molecules.

Kinetic Molecular Theory All molecules are in motion. The three states of matter have different motions. When molecules collide with other molecules or the sides of containers, no energy is lost.

Solids The intermolecular forces between molecules of solids are very strong. Has a definite volume Has a define shape Low energy Molecules in a solid move by vibrating in place. Picture:

Liquids The intermolecular forces between molecules of liquids are medium strength. Has a definite volume The shape depends on the container Medium energy Molecules in a liquid move by sliding past each other. Picture:

Gases The intermolecular forces between molecules of gas are very weak. No definite shape No definite volume High energy Molecules in a gas move by rapid, random motion. Picture:

Phase Changes A phase change is when molecules of a substance change spacing between molecules. Causes: change in temperature change in pressure.

Melting A solid becomes a liquid

Freezing A liquid becomes a solid

Boiling A liquid becomes a gas

Condensing A gas becomes a liquid

Sublimination A solid becomes a gas.

Deposition A gas becomes a solid.

Phase Change Summary

Energy Changes Endothermic – heat is taken in by the object. Exothermic – heat is released by the object.

Physical Properties Describes characteristics of materials that can be observed without changing the material. Color Density Hardness Texture Phase

Physical Changes Physical changes affect the physical properties of a substance. The chemical is the same before and after the change Key Verbs: Distill Break Boil Melt Heat

Chemical Properties/Chemical Change Chemical properties describe how chemicals interact with each other A new chemical is formed Key verbs: Bubbling, color change, new material Burning Combusting