1. Matter Chapter 2.1 & 2.2 Notes

2. What is Matter? Matter is anything that has mass and takes up space Air is matter because it has mass and takes up space; light and sound are not matter because they have no mass or volume All matter is either an element, compound, or mixture

3. States of Matter Solid: definite shape and volume Example: your desk, pencil, etc. Liquid: no definite shape, definite volume Gas: no definite shape or volume Plasma: approximately 99% of known matter in the universe, including the sun and other stars No definite shape or volume

4. Elements A substance that cannot be broken down into simpler substances by chemical means Examples: copper, carbon, iron, etc. Atom: smallest unit of an element; every element is made up of only one kind of atom Elements are represented by a one- or two-letter symbol (found on the periodic table) Copper: Cu; Carbon: C, Iron: Fe

5. Compounds A substance made up of atoms of different elements Each molecule of a compound contains two or more elements that are chemically combined Properties of compounds differ from the properties of the individual elements that make up the compound Water is a compound made up of two hydrogen atoms and one oxygen atom; at room temperature, hydrogen and oxygen are gases but water is a liquid

6. Chemical Formulas Shows how many atoms of each element are in a unit of substance The number of atoms of each element is written as a subscript after the element’s symbol If only one atom of an element is present, no subscript is used Example: H 2 O

7. Pure Substances and Mixtures Pure substance: matter that has a fixed composition and definite properties Elements and compounds are pure substances Mixture: combination of substances that are not chemically combined Mixtures can be physically separated into their parts

8. Classification of Mixtures Heterogeneous mixtures means that you can see the different components as individual substances Sand in water; oil and water; pulp in orange juice Homogeneous mixtures have the same composition throughout Air, salt water Miscible mixtures contain liquids that can be mixed Gasoline contains at least 100 different liquids Immiscible mixtures contain liquids that cannot be mixed If you mix oil and water, they will separate into two layers

9. Physical Properties Properties that describe the look or feel of a substance, such as color, hardness, density, texture, and phase Physical properties can change when conditions change, but the substance remains the same Liquid water vs. solid ice: it’s still H 2 O

10. Chemical Properties Properties that characterize the ability of a substance to react with other substances or to transform from one substance to another Involves a change in the way the atoms are chemically bonded to one another Chemical bonds are the attractions between atoms that hold them together in a molecule Flammability: the ability to burn Reactivity: capacity of a substance to react with another substance

11. Comparison of Physical and Chemical Properties SubstancePhysical PropertyChemical Property WoodGrainy textureFlammable IronBends without breakingReacts with oxygen to form rust Red DyeHas red colorReacts with bleach; loses color

12. Separation of Mixtures Filtration: separating a solid-liquid mixture Example—using filter paper that allows the liquids to pass but not the solids (making coffee) Distillation: the process of collecting a vaporized substance Example—seawater is a mixture of water and sodium chloride. Water boils at 100°C, but sodium chloride doesn’t even melt until we reach 800°C. We can heat the seawater to 100°C and collect the water vapor in a separate container to cool and condense into liquid water without the sodium chloride.

13. Homework Read chapter 2 sections 1 & 2 http://my.hrw.com Ask me if you need your username/password again! Worksheet: “Fundamental Properties of Matter”