CHAPTER 2 : MATTER AND CHANGE Learning Goal: SWBAT understand that matter is classified based on its physical and chemical properties, and matter can undergo both physical and chemical changes.. 2-1:Properties of Matter 2-2: Mixtures 2-3: Elements and Compounds

CHEMISTRY IS A PHYSICAL SCIENCE Learning Goal: SWBAT describe what Chemistry is and its scope. Chemistry is the scientific study of matter-its composition, structure and properties and the changes matter undergoes. Scientists who study chemistry are called chemists.

Branches of Chemistry

Matter is defined as anything that occupies space and has mass. Some types of matter—such as steel, water, wood, and plastic—are easily visible to our eyes. Other types of matter—such as air or microscopic dust—are impossible to see without magnification. 2.1 Properties of Matter

Describing Matter

Properties of matter Intensive Properties Depends on the type of matter and not the amount of matter Ex: Color,uster,B.P,M.P, hardness,conductivity,vis cosity Extensive Properties Depends on the amount of matter in a sample. Ex: Mass, Volume, Weight, Density.

Three States of Matter

Classification of Matter

2.3 Elements and Compounds Are Pure Substances Elements Cannot be broken down into simpler substance by physical or chemical means. Smallest particle is an atom Represented by a one or two letter chemical symbol.(first letter uppercase; if second letter- lower case Examples: Hydrogen, oxygen, fluorine, chlorine Compounds Always contain atoms of 2 or more elements joined in a fixed proportion. Can be broken down into those simpler substances by chemical processes. Represented by chemical formula. Examples: water, carbon dioxide, iron oxide

2-2 Mixtures have variable composition and can be separated by physical methods Homogeneous Mixtures Prefix “homo” indicates same. Has same uniform appearance and composition throughout. Commonly referred to as solutions Ex: salt solution, sugar solution, gatorade, soda Heterogeneous Mixtures Prefix “ hetero” means different. Consists of visibly different substances or phases. Ex: beach sand, salad, seawater

Physical Property and Physical Changes A physical property can be observed or measured without changing the composition of the substance. Ex: B.P, M.P, viscosity, hardness, density (identification tag) A physical change does not involve a change in the composition or identity of the substance. Examples of Physical Changes: cutting hair, cutting or crumpling a piece of paper, melting, boiling

2.4 Chemical Reactions A Chemical property produces a change in the composition of the substance. New substance is produced Ex: Flammability, Reactivity A chemical change also called a chemical reaction involves a change in the composition of the substance. Examples of chemical changes: burning, cooking, respiration, digestion, rusting, food spoiling. Words that signify a chemical change has occurred-burn, rot, rust, corrode, decompose, ferment, explode

3 Clues that a chemical change has taken place: 1)Change in color : ex: silver tarnishes, fall leaves, match burns, apple after cutting 2) Formation of a precipitate: ex: lemon added to milk causes curdling 3) Production of a gas: ex: vinegar + baking soda Chemical Reaction : A change in which one or more substances are converted into different substances is called a chemical reaction Ex: C + O  CO 2 H 2 + O  H 2 O Filtration and Distillation are two processes used to separate mixtures. Filtration is a process used to separate materials based on size of the particles. Distillation is a process that separates the substances based on their boiling points.

Antoine Lavoisier [1743 – 1794] States that during any physical or chemical reaction, mass is conserved. In other words, mass of the products is always equal to the mass of the reactants. There is no new matter. The total amount of matter remains constant. Matter is neither created nor destroyed in a chemical reaction. Law of Conservation of Mass

Suppose that we burn 58 g of butane in a lighter. It will react with 208 g of oxygen to form 176 g of carbon dioxide and 90 g of water. Law of Conservation of Mass