Chemistry

5.1 - INTRODUCTION TO CHEMISTRY Is the study of the; structure, composition and properties of matter changes in structure, composition and properties of matter energy needed or resulting from the changes in matter

Matter Matter is anything that occupies space (has a volume) and has a mass (ex. person, desk). Matter can be classified into two categories: Pure substances and Mixtures. Matter Pure Substances Mixtures

Pure Substances Pure Substances Elements Compounds Pure substances are made up of the same type of particle and look the same microscopically and macroscopically. Its properties would also be the same throughout. Pure substances can be divided into 2 categories: Elements and Compounds. Pure Substances Elements Compounds

Elements Are pure substances made up of particles that cannot be broken down into simpler substances. There are over 100 different elements that are found on the Periodic Table of Elements. An atom is the smallest part of an element. Not all elements are found in nature alone. Some exist as multiples of the same element (H2, N2, O2, I2).

Compounds   Are pure substances made up of particles that can be chemically broken down into simpler substances that are elements (water broken down into hydrogen and oxygen). A molecule is the smallest part of a compound. One molecule of water is made up of 2 atoms of hydrogen and 1 atom of oxygen. A formula is the symbol and the number used to represent a compound H2O.

Mixtures Are made up of 2 or more pure substances that have been physically mixed together. The different particles may not be seen macroscopically or microscopically. A mixture has different properties throughout. It is possible to separate back into original pure substances. Ex: Salt (NaCl) and sand (silica) is a mixture of 2 pure substances that are compounds. They can be separated using water because salt will dissolve in water, leaving the sand.

Properties of a Substance The characteristics of substance. They may be used to identify a substance. Qualitative property is one in which a describing word is used (ex. colour, state of matter, etc.). Quantitative property is one that uses numbers in order to describe it (ex. melting point, density,…)

Physical Properties A description of a substance that does not involve forming a new substance Examples include: colour, texture, density, smell, solubility, taste, melting point, and physical state)

Physical Changes Physical Change of a substance occurs when the size, shape, location or physical state is altered. The structure and composition is not changed. No new substance is produced. It is usually reversible. If you melt a block of ice, you still have H2O at the end of the change. If you cut a piece of paper, the size and shape of the paper has changed but it’s still paper

Different types of physical changes….. Cutting Tearing Breaking Shredding Shrinking/Enlarging Bending Changes of state Crushing Moving Dissolving Rotating Grinding

Chemical Properties Properties that describe how a substance changes into a new substance. The structure and composition is changed and one or more new substances are produced. It is usually irreversible. The starting materials of such a change are called reactants and the new materials produced are called products.

Evidence that a chemical change has occurred….. Gas forms (bubbles) without heating Colour change Odour Change Energy is given off or taken in Precipitate forms Example: a reaction of an acid with a base, flammability, bleaching ability, corrosion, iron reacts with water to form rust).

Scale Microscopic scale means that a microscope is needed to see a certain property because of the smallest of its size. Macroscopic scale means that the unaided eye may see a particular property.